Equipment Reviews – The Amazing Sky

December 6, 2024February 14, 2025

Testing Wide-Angle Lenses on Nikon Z for Astrophotography

I test a trio of wide-angle, auto-focus lenses for astrophotography, all for Nikon Z mount: the Nikkor 20mm f/1.8 S, the Viltrox 16mm f/1.8, and the Laowa 10mm f/2.8 Zero D.

As a bonus, I also test a fourth lens: the TTArtisan manual-focus 7.5mm f/2 fish-eye.

NOTE: Images are large and may take a while to load.

While the selection of lenses for Nikon Z mirrorless cameras is not as diverse as it is for Sony E-mount, Nikon shooters have more brands of lenses to pick from than do users of Canon R mirrorless cameras. For nightscapes and Milky Way photography we want fast, wide-angle lenses, usually in the 14mm to 24mm range.

Canon, Nikon, and Sony all have excellent zoom lenses that cover the range. I use Canon’s RF 15-35mm L lens a lot, and reviewed it here on my blog from 2022.

But all these wide-angle zooms are f/2.8. While that’s a good speed for most astro work, having an even faster lens can be valuable. An aperture of f/2 or faster allows for:

— Shorter exposures for untrailed stars when shooting just on a tripod with no tracker.

— Capturing fainter and more numerous meteors during a shower.

— Rapid-cadence time-lapses of auroras, freezing the motions of curtains.

— Real-time movies of auroras and satellite passages at lower, less noisy ISO settings.

The Nikkor 20mm at f/1.8 allowed a short 1.3-second exposure for capturing the aurora from a ship off the coast of Norway, to minimize ship motion trailing the stars.

Also, stopping those faster lenses down to f/2.8 can sometimes yield better image quality than shooting with a native f/2.8 lens wide open.

Canon and Sony each have fast f/2 zooms that cover the range from 28mm to 70mm. While those focal lengths can be useful, both lenses are expensive and heavy. And they are still not wide enough for many astro subjects. For fast lenses with even shorter focal lengths we need to turn to “prime” lenses, ones with fixed focal lengths.

As of this writing Canon has few fast, wide primes for their RF lens mount (their new 24mm f/1.4 VCM is a costly choice designed primarily for video use). A few third-party lens makers offer fast (f/2 or faster) primes for Canon full-frame cameras, always as manual focus lenses. For example, Laowa has a 15mm f/2, and TTArtisan has a 21mm f/1.5.

Yes, Sigma now offers auto-focus 16mm and 23mm f/1.4 primes, and Samyang has a new 12mm f/2, but they are only for Canon RF-S cropped-frame cameras. Canon has yet to allow other companies to produce auto-focus lenses for their full-frame cameras.

Nikon has been restrictive as well. Sigma’s much-lauded Art series that includes the 14mm rectilinear (i.e. the horizon remains straight) and 15mm fish-eye (with a curved horizon), both f/1.4 and aimed at astrophotographers, are not offered for Nikon or Canon, only for Sony E-mount and Panasonic/Leica L-mount cameras.

However, while Sigma lenses are missing, there is a wider choice of third-party lenses for Nikon Z-mount compared to Canon RF, plus Nikon itself makes a very fine 20mm prime in their premium S-series.

That’s what I test here — three wide-angle rectilinear primes for Nikon Z: A 20mm Nikkor, and two third-party primes: one from Viltrox, their 16mm; and one from Laowa, their new 10mm.

As a bonus, I add in a test of a fast fish-eye lens, from TTArtisan, their 7.5mm f/2.

NOTE: All test images can be downloaded as full-resolution JPGs for closer inspection. Click or tap on the images.

Prices are from B&H Photo, but will vary with sales and special promotions.

The Nikkor 20mm S-Line Lens ($1,050)

I shot the northern summer Milky Way (below) with the three rectilinear wide-angle lenses (meaning these are not fish-eyes) with the camera on a star tracker, to prevent star trailing. The tracker was the Move-Shoot-Move Nomad, reviewed here on my blog.

The Nikon Z6III and 20mm Nikkor on the MSM Nomad tracker.

I shot with Nikon’s new Z6III, a 24-megapixel full-frame camera I reviewed in the December 2024 issue of Sky & Telescope magazine. It offers a number of excellent features for nightscape photography. Most notably, auto-focus lenses zip to the infinity focus point automatically when the camera is turned on, something I wish Canon cameras would do.

The Nikkor 20mm has a field of view along the long dimension of 84°.

The Nikkor 20mm is the widest prime lens in Nikon’s premium S-Line series. It offers what I consider to be an ideal focal length for most nightscape and wide-field Milky Way images.

While a 14mm lens is often thought of as the default nightscape lens, a 20mm presents less distortion (objects leaning in or stretched out at the corners) and a more natural perspective. Plus the lens can be made faster (in this case f/1.8), smaller, and not cost as much as an ultra-fast 14mm like the Sigma f/1.4 Art lens.

Nikkor 20mm Corner Aberrations

The four panels show the upper left corner, in the area outlined in the inset that shows the full frame.

Sharp stars right to the corners is the ideal for all forms of astro images. We don’t want stars to turn into winged seagulls or coloured streaks. They should remain as pinpoint as possible.

The Nikkor 20mm shows very little aberrations across the frame. Stars are elongated by tangential astigmatism and discoloured by lateral chromatic aberration only slightly and only at the extreme corners.

Stopping down the lens decreased the aberrations, but some residual astigmatism remained, even at f/4. However, the corner aberrations are low enough, and so restricted to the very corners, that this is a lens you can certainly use wide open at f/1.8, or perhaps at f/2, without any penalty of image sharpness.

Nikkor 20mm Vignetting

The four panels show the left side, as outlined in the inset. The inset is the f/1.8 sample.

Ideally, we also want images to be as fully-illuminated across the frame as possible. Light fall-off, or vignetting, creates dark corners with less signal reaching the sensor. Less signal gives rise to more noise, noticeable when brightening the corners in processing. That can reveal unsightly noise, banding, and discolouration in nightscapes, especially in the ground, often the darkest part of a scene, not the starry sky.

The 20mm shows a fair degree of edge and corner darkening when wide open at f/1.8. Stopping the lens down to f/2 improves the field illumination notably. And by f/2.8 the field is fairly uniformly lit. There is little need to go as slow as f/4.

In all, the Nikkor 20mm S is a superb lens ideal for nightscapes and Milky Way images.

The Viltrox AF 16mm STM ASPH ED IF ($580)

The new company Viltrox has been making a name for themselves recently with the introduction of a number of top-quality pro-grade lenses to compete with the best from any brand, and at much more affordable prices.

The horizontal field of view of the Viltrox 16mm is 100°.

Their 16mm is an auto-focus lens that, on the Nikon, can actually auto-focus on stars, as can the Nikkor 20mm. However, it, too, will zip to infinity focus when powered up. Plus two function buttons can be programmed to rack between two preset focus distances, one of which can be infinity.

The buttons at left are for preset distances.

A manual aperture ring (above left) has 1/3rd-stop detents, or it can be set to A for controlling the aperture in the camera.

A colour OLED display (above right) shows the focus distance and aperture, a nice way to confirm your settings at night. The display is too bright on the darkest nights; I cover it with red gel.

An option to turn it red using the Viltrox app would be welcome. Or to turn it off! ….

NOTE ADDED FEB 24, 2025 — I tested all lenses on a stock camera. But when used on an astro-modified camera with greater red and infra-red sensitivity, the Viltrox 16mm can add a noticeable red glow or flare to images, as a colleague has found and reported to me. I did confirm this with very long exposures and high ISOs with my stock Z6III. It barely shows up in dark frames boosted a lot for brightness (see below – it’s the faint magenta band across the centre of the frame).

But in modded cameras it is much more obvious. This comes from the lens’s top OLED display. The trick is to slightly dismount the lens, which turns the display off, but still maintains data contact to the camera. Viltrox is aware of the issue and has said they will fix it in a firmware update.

With Viltrox lens fully engaged and display ON

Uniquely, this and other Viltrox lenses have Bluetooth built in, for direct connection to a mobile device for firmware updates and lens settings, shown above. However, I found the app buggy; it would connect to the lens, but then refuse to allow settings to be changed, claiming the lens was not connected. Or the app would freeze, disconcerting during a firmware update. Luckily, that did not brick the lens.

Viltrox 16mm Corner Aberrations

The four panels show the small corner area outlined in the centre inset that shows the entire image.

At the extreme corners, the Viltrox shows some softness (perhaps from field curvature), but only minimal astigmatism and lateral chromatic aberration when wide open at f/1.8, and slightly sharper corners at f/2. At f/2.8 corner performance is nearly perfect, and certainly is at f/4.

This is a level of aberration correction even the most premium of lenses have a hard time matching.

Viltrox 16mm Vignetting

The panels show the left side outlined in the centre inset, which shows the f/1.8 image.

As is often the case with wider lenses, the Viltrox does show a great deal of vignetting at f/1.8, more so than the Nikkor 20mm. While this can be corrected in processing it will raise noise levels.

Stopping down to just f/2 helps, but the field becomes more uniform only at f/2.8, the sweet spot for this lens for the best all-round performance. But it offers the speed of f/1.8 when needed, such as for auroras.

If you prefer a wider field than a 20mm provides, the Viltrox 16mm (also available for Sony) is a great choice that won’t break the bank. Until Canon changes their third-party lens policy, Canon owners are out of luck getting this excellent lens.

The Venus Optics/Laowa 10mm Zero-D FF ($800)

The Laowa also accepts 77mm filters, unusual for such a wide lens..

The lens maker Venus Optics (aka Laowa) is known for its innovative and often unusual lens designs.

Introduced in 2024, their new 10mm offers the widest field available in a rectilinear (not fish-eye) lens for full-frame cameras. The “Zero-D” label is for the lens’s lack of pincushion or barrel distortion. Horizons remain straight no matter where they fall on the frame. However, objects at the corners become elongated a lot.

The Northern Lights in a superb display on August 11-12, 2024, at Grasslands National Park, Saskatchewan. This is with the Laowa 10mm wide open at f/2.8 on the Nikon Z6III at ISO 6400.

Even so, there’s a lot to be said for having a field that extends for 130° across the long dimension of a full-frame sensor. That’s more than enough to go from well below the horizon to past the zenith when the camera is in portrait orientation. Even in landscape orientation (as above) the lens covers nearly a 90° field across the short dimension, enough to go almost from horizon to zenith.

The f/2.8 speed is slower than the other lenses on test here, but is still faster than most ultra-wide lenses. Remarkably, it accepts common 77mm filters, the same as the Nikkor 20mm and Viltrox 16mm.

The 10mm is available as an auto-focus lens for Sony E and Nikon Z, and in manual focus versions for Canon RF and Panasonic L, oddly all at the same price.

Laowa 10mm Corner Aberrations

The four panels show the corner area outlined in the inset, at four apertures between f/2.8 and f/4.

Corner aberrations are much worse than in the 20mm and 16mm lenses, showing a fair degree of tangential and sagittal astigmatism, elongating stars radially and adding wings to them, respectively. The aberrations are larger and reach deeper into the frame than in the Nikkor and Viltrox lenses.

There’s also some lateral chromatic aberration adding blue and purple fringes to the stars at the corners. Stopping down to f/4 improves, but doesn’t eliminate, the aberrations.

Laowa 10mm Vignetting

The four panels show the left side, as outlined in the inset, which shows the f/2.8 image.

Edge and corner darkening were also worse than in the other lenses and required about a +50 setting to correct in Adobe Camera Raw, far less than the maximum of +100. So it’s still quite acceptable and correctable.

However, while stopping the lens down to f/4 improves vignetting, it does not eliminate it, still requiring a +40 correction. Vignetting will be a factor to deal with in all astrophotos with this ultra-wide lens.

Laowa 10mm Lens Flares

Three panels showing the Moon framed in the left corner (L), centred (C), and in the right corner (R).

With such a wide lens, the Moon or other bright light sources are bound to be within the frame. The Laowa exhibits a prominent internal lens flare when bright objects are in the corners, but just in the corners. Objects near the edge but centered are fine.

Showing the effect of decreasing aperture on the lens flare and bright light source.

Stopping down the lens adds diffraction spikes (or “sunstars”) to bright lights, but doesn’t eliminate the circular internal reflection. None of this is a serious issue for most images, but it is something to be mindful of when framing nightscapes.

With the Laowa 10mm lens at f/2.8 on the Nikon Z6III at ISO 3200. Note the Big Dipper at left and Orion at right.

In Milky Way and starfield images, constellations in the corners can distort into unnatural shapes that look odd, as I show above. While the lens can take in a great swath of sky, its distortion and corner aberrations make it less than desirable for tracked Milky shots.

An aurora in the dawn twilight on September 17, 2024. A 4-second exposure with the Laowa 10mm at f/2.8.

Where the Laowa 10mm really proves its worth is for auroras, as above, which can require as wide a field as you can muster. Note the flat horizon.

For ultra-wide nightscapes in a single image (not a panorama) with a natural looking (not curved) horizon, and for meteor showers, the Laowa is just the ticket.

BONUS TEST: The TTArtisan 7.5mm f/2 Fish-Eye ($140)

The TTArtisan has a fixed lens hood. Front filters are not possible without vignetting.

Technically, this lens is designed to be used on cropped-frame (or APS-sensor) cameras where it fills the frame with a curving horizon. But it works on a full-frame camera where it projects a circular image slightly larger in diameter than the short dimension of the frame, so not a complete circle as with a true circular fish-eye like the old Sigma 8mm f/3.5.

An aurora in the dawn twilight on September 17, 2024 in a 2-second exposure with the TTArtisan 7.5mm fish-eye lens at f/2 on the Nikon Z6III at ISO 800.

For all-sky auroras, this is ideal, where the TTArtisan’s fast f/2 speed is unprecedented in a fish-eye lens. That makes rapid-cadence time-lapses possible, as well as real-time movies. An example is here on my YouTube channel.

A stack of 4 x 4-minute exposures with the TTArtisan 7.5mm f/2 fish-eye lens stopped down to f/2.8 on the Nikon Z6III at ISO 1600, on the MSM Nomad tracker.

Or you can just capture the Milky Way from horizon to horizon, as above. For the latter, having stars sharp across the circular field is still desirable.

I have this lens for Canon RF as well, but that unit shows a noticeable softening of the left edge with defocused stars, likely from lens de-centering. I was told by TTArtisan that was a normal unit-to-unit variation and not a defect warranting replacement. Annoying!

I hesitated to buy one for my Nikon. But this is such a unique lens, and so affordable, I took the chance. The Nikon Z-mount version proved much better.

TTArtisan 7.5mm Edge Performance

There is no corner performance or vignetting to test here.

TTArtisan 7.5mm lens at f/2, showing the left side area shown in the blowups below.

Instead, I’m inspecting the same side on the Nikon Z version that caused a problem on my Canon version.

Comparing f/2 and f/2.8 edge aberrations.

The Nikon version looks fine, with stars sharp along the edge even at f/2, showing just a low level of astigmatism, to be expected in such a fast, wide lens. Stars tighten up a bit more at f/2.8. Most critically, the field was flat and in focus across the frame. There was no evidence of lens de-centering or optical defects.

The edges do show some discolouration and a soft edge to the image area. I also see two odd dark protrusions at the top of the frame. Looking through the lens, there’s nothing obvious intruding into the light path.

Keep in mind when used on a full-frame camera you’re seeing more of the projected image than was intended in the design.

The 7.5mm lens comes with a metal lens cap with a threaded centre disk. Remove it to create an aperture that vignettes the image to a smaller but complete circle.

The TTArtisan 7.5mm is a specialty lens to be sure. But at its low price it isn’t a big outlay to include in your lens arsenal, for unique all-sky images, of auroras, satellite passages, sky colours, and the Milky Way. And it is terrific for time-lapses and movies of the whole sky. It is a no-frills manual lens available for most camera mounts.

Recommendations

The Viltrox 16mm, Laowa 10mm and TTArtisan 7.5mm are all available for Sony E-mount. The Laowa and TTArtisan are available for Canon RF, but the Viltrox 16mm is not, as it is an auto-focus, full-frame lens, the class of lenses Canon has yet to allow on their RF mounts, much to the disdain of all concerned but Canon management it seems.

Viltrox 16mm — For nightscape use, the Viltrox 16mm might be the single best choice, as being the most versatile and affordable of the trio of wide-angle lenses. Its focal length is a good balance between the usual 14mm and what I think is a more useful 20mm.

Nikkor 20mm — I like the Nikkor 20mm for its lower level of vignetting, slightly tighter framing, and very sharp stars. I think a 20mm is an ideal focal length for many nightscapes and Milky Way scenes. But it is the most expensive lens tested here.

Laowa 10mm — While nearly as costly as the Nikkor 20mm, the Laowa 10mm is much more specialized and, I think, not as useful as the others for general nightscape and Milky Way shooting. But it is superb for auroras, if you are in a place where they are common, as they are here in Alberta. Otherwise, I think you’d find the 10mm a costly lens that might not see a lot of use for astrophotography. Its real forté is architecture and real-estate interiors.

TTArtisan 7.5mm — Ditto on its limited use. But it is so affordable it’s easy to justify even if it doesn’t get a lot of use. The astro images, time-lapses, and movies it can produce are unique and impossible to create any other way. Be sure to buy it from a source where you can return it easily if you find your sample defective.

Reason To Go Mirrorless

The quality of these and other premium lenses from Nikon, and also from Canon, Sony and third-party makers like Sigma and Viltrox, is one of the major benefits of migrating to mirrorless cameras. DSLRs, and the lenses made for them, are now effectively dead as new gear choices.

Yes, mirrorless cameras can be better in many aspects of their operation than DSLRs. But it is the lenses made for mirrorless that show the greatest improvement over their DSLR equivalents, many of which date back to the forgiving film days.

— Alan, December 6, 2024 (amazingsky.com)

June 27, 2024June 28, 2024

Testing the MSM Nomad Tracker

The new star tracker from Move Shoot Move improves upon their original model, eliminating its flaws to provide a reliable and compact tracker.

A few years ago the start-up company Move Shoot Move (MSM) introduced a low-cost (about $250), compact star tracker they called the Rotator. Like all other star trackers, the Rotator allowed a camera to follow the turning sky for untrailed, pinpoint stars in long exposures.

Trackers are essential for rich Milky Way images, and are great for nightscapes, for shooting the sky, blended with untracked shots of the ground, as I show in examples below.

The original Rotator (L) and new Nomad (R). The Nomad is even smaller than the Rotator.

Out with the Old …

The original Rotator went through a couple of design changes during its lifetime. I tested the last versions to be marketed, using three different sample units I either purchased or were sent to me by MSM. (My reviews appeared in 2019 on my blog here, and in the June 2021 issue of Sky & Telescope magazine.)

The bottom line is that I found all the samples of the Rotator I tested to be unreliable for accurate tracking, indeed for tracking period, as units would sometimes not start tracking for a few minutes, or just stop tracking mid-shoot and then restart intermittently. Getting a set of untrailed exposures was a hit or miss affair.

But with a cost lower than most other trackers on the market (ostensibly, as explained below), a pocketable compact size, and with endorsements from notable nightscape photographers, the original Rotator garnered a loyal following of fans. I was not one of them.

MSM obviously recognized the design flaws of the Rotator, because in early 2024 they replaced it with an all-new model, dubbed the Nomad. It works!

The Nomad on the Benro 3-Way Head, with Laser and Polar Scope, and with a camera and 135mm lens. The ball head is not one from MSM.

I purchased a unit in January 2024 when the Nomad came out, and have used it extensively and successfully over the last few months. I found it has addressed all the serious flaws of the Rotator.

Polar Alignment Accessories

With a weight of about 400 grams, the Nomad is about 70 grams lighter than the old Rotator. It is one of the lightest and smallest trackers on the market, a benefit for those wanting to hike to remote nightscape sites, or pack gear for airline travel. (I took my Nomad to Australia this year; one result is below, shot with the Nomad.)

This frames the spectacular area of the southern Milky Way from Centaurus at left, to Carina at right, with Crux, the Southern Cross, at centre. This is a stack of 8 x 4-minute exposures with the Canon RF28-70mm lens at 48mm and f/2.8, on the Canon Ra at ISO 800. All on the MSM Nomad tracker.

However, unlike the popular Star Adventurer 2i and Mini trackers from Sky-Watcher, the Nomad, like MSM’s older Rotator, does not have a polar alignment scope built in, just a peep sight hole. That makes it easier for MSM to fit a tracker inside a compact box.

And yet, I feel some form of polar alignment aid (not just a peep sight) is essential if a tracker is to follow the sky accurately. Like the Rotator, the Nomad can be purchased with two add-on choices (shown below):

• a 5 mw green laser pointer,

• and an optical polar scope …

… each of which attaches to the side of the Nomad as outboard accessories. I purchased both, bundled with the Nomad as “Basic Kit C” for $309 U.S., and find both accessories useful.

NOTE: When shopping at the MSM website don’t be fooled by what looks like temporary sale prices. The prices are always marked down, though MSM does offer coupon codes now and then for genuine discounts. I’ve always found MSM’s delivery by parcel post prompt, and in my case, shipments came from a warehouse in Canada, not China.

The Laser and Polar Scope as they come supplied

As with the Rotator, the need to add essential accessories makes the Nomad more expensive and more complex to pack than buyers might think. And it can be more complex to initially set up than imagined, not helped by the lack of any instructions. (I’m told by MSM that a downloadable PDF sheet is being prepared.) In place of factory-supplied instructions, MSM depends on its YouTuber fans to provide tutorials.

It took me a moment to figure out how the laser attaches to the Nomad — it does so by replacing the black cap that comes on the laser with a supplied threaded red cap, so the laser can screw into the peep hole on the Nomad’s body that is covered by yet another cap you remove — but don’t lose it, as you might need it.

The optical polar scope attaches by way of an included clamp held onto the Nomad by the laser, or by the removable threaded cap (so you will need it if you aren’t using the laser, but it is easily lost).

Out of the box I found I had to adjust the beam of the laser (using the two tiny set screws on the laser) so the beam exited straight out the laser and up the peep hole in the Nomad’s case.

Once collimated, the laser pointer has proved to be an accurate and convenient way to polar align, especially for shooting with wide-angle lenses. (Keep in mind, green laser pointers over 1 mw are illegal in some jurisdictions.)

The laser uses a removable and rechargeable 3.7-volt battery, and comes with a little USB-powered charger. The laser’s battery has lasted for months of momentary use. The laser works briefly in winter when it is warm, but as soon as it gets cold, as is true of most laser pointers, it refuses to lase!

This frames the small constellations of Sagitta the Arrow and Vulpecula the Fox.
At lower left is the green planetary nebula Messier 27, aka the Dumbbell, shown in the close-up tracking test image below. This is a stack of 14 x 2-minute exposures with the Canon RF135mm lens on the Canon Ra, on the MSM Nomad tracker. The images were the best 14 out of a series shot to test the Nomad’s tracking.

However, for the more accurate polar alignment needed when shooting with telephoto lenses (an example is above), and for winter use, I prefer to use the optical polar scope, with the laser a handy complement just to get close to the pole.

The polar scope has a reticle etched with star patterns for both the North and South Celestial Poles. I found the latter worked well in Australia. The mounting clamp held the polar scope securely and consistently well centered, another welcome improvement over the polar scope clamp supplied with the Rotator, which could wiggle around.

Polar scope with its glow-in-the-dark Illuminator. The Nomad comes with an Arca-Swiss dovetail plate bolted onto the bottom edge, for attaching it to a tripod head or to the optional MSM Wedge.

The polar scope does not have an illuminator LED. Instead, it comes with a novel phosphorescent cap which you hit briefly with white light so it glows in the dark.

Placed over the front of the polar scope, it lights up the field allowing the reticle to be seen in silhouette. While it works fine for sighting Polaris, the bright field can make it hard to see the faint stars in Octans around the South Celestial Pole.

The Nomad on the Benro 3-Way Geared Head, using the Arca-Swiss attachment plate. Another method of mounting the Nomad to the Benro is shown below.

To aid polar alignment I purchased the Benro 3-Way Geared Head, also sold by MSM but available from many sources. Its geared motions make it easy to aim the tracker’s rotation axis precisely at the pole and hold it there solidly.

The Benro accepts standard Arca-Swiss mounting plates, so I’ve found it a useful head to have for other purposes and gear combinations. It has replaced my old Manfrotto 410 3-axis head which uses a proprietary mounting plate.

However, MSM also sells its own latitude adjustment Wedge which, at $90, is a cheaper alternative to the $200 Benro. I’ve not used the MSM Wedge, so I can’t say how solid and precise it is. But the Wedge is lighter than the Benro head, and so may be a better choice when weight is a prime consideration.

I would recommend either the Wedge or Benro for their fine adjustments of azimuth and altitude that are essential for easy, yet precise and stable polar alignment.

Tracking Accuracy

All-important is how well the Nomad tracks. When shooting with wide-angle lenses (14mm to 35mm) for nightscapes and wide Milky Way shots, the majority of images I’ve taken over the last few months, using exposures of 1 to 3 minutes, have been reliably well tracked, with pinpoint stars.

The Nomad begins tracking right away, with no wait for gear backlash to be taken up, or for the drive mechanism to settle in. I also found no tendency for tracking to be better or worse with camera position, unlike the Rotator that seemed to work better with the camera aimed at one area of sky vs another. And the Nomad didn’t suffer from any stalls or moments when it just stopped in its tracks, again unlike the problematic Rotator.

20 consecutive 2-minute exposures with a 135mm lens, to show the variations in tracking accuracy. Tap on the image to download it for closer inspection.

As with any tracker, where you do see mistracking is when using longer lenses. I tested, and indeed have used, the Nomad with 85mm and 135mm telephoto lenses, as many owners will want to do, for close-ups of Milky Way starfields and for so-called “deepscapes.” (An example of the latter is at the end.) The demo image above shows blow-ups of consecutive frames from the 135mm shoot of the Vulpecula/Sagitta starfield shown earlier.

In those more demanding tests, as I demonstrate here, I found that typically about 50% to 60% of images (taken with 1- to 2-minute exposures) were tracked well enough to be usable. The longer the focal length used, or the longer the exposures, the more frames will be trailed enough to be unusable in an image stack. And a well-tracked frame can be followed by a badly tracked one, then the next is fine again. That’s the nature of small drive gears.

As with other trackers, I would suggest that the Nomad is best used with lenses no longer than a fast 135mm. Even then, plan to shoot twice as many frames as you’ll need. Half may need to be discarded. While I know some users will want to push the Nomad beyond its limits, I would not recommend burdening it with monster telephoto lenses or small telescopes. Like all other trackers, that’s not its purpose.

When there was mistracking it was usually in the east-west direction, due to errors in the drive mechanism, and not north-south due to flexure. (If it occurs, north-south drift is likely due to poor polar alignment.)

I found the Nomad did indeed turn at the sidereal rate to follow the stars, something I was never confident the Rotator actually did.

While you might think a 50% success rate with telephotos is not good, in fact the Nomad’s tracking performance is on par with other competing trackers I’ve used, from Sky-Watcher and iOptron. At wide-angle focal lengths the success rate proved closer to 100%.

So for a tracker as compact as the Nomad to perform so well is very welcome indeed. It’s the main area where the Nomad beats the old Rotator by a long shot!

NOTE: While the MSM website mentions an “optional counterweight system,” as of my review’s publication date it is still being developed, MSM tells me. However, I don’t feel it will be necessary for the Nomad’s main purpose of wide-field imaging.

Mechanical Stability

Another flaw of the old Rotator was that it had several single-point attachments that, under the torque of a turning camera, could cause the camera to come loose and suddenly flop down.

Exploded view of the ratcheted mounting plate to attach a ball head to the Nomad

The Nomad uses a ratcheted clamp to attach a user-supplied ball head to the tracker body, and that clamp has an additional safety set screw to help ensure the ball head does not unscrew itself as a camera turns.

I’ve had no issues with cameras coming loose. Of course, the solidness of the ball head used will be critical as well. A large ball head can be better, but introduce some of the issues I report on below.

While MSM offers its own ball head, I have not used it, preferring to use a couple of other ball and pano heads I like, and that I show in the images here.

Simplicity of Operation

The Nomad improves upon the old Rotator by doing away with all its time-lapse features. You might think that eliminating features can’t be an improvement, but in this case it is.

I suspect few owners used the Rotator’s preset functions for slowly turning a camera along the horizon while firing the camera shutter between each incremental time-lapse move (the very function that gave the company its name!). The Rotator’s options for creating time-lapses were confusing to set up and limited in their choice of speeds. A serious time-lapse photographer would never use it.

(If you do want a tracker with time-lapse motion-control capabilities the Star Adventurer Mini works well. Its WiFi connection and mobile app allows a user to set all the factors needed for a good time-lapse: interval, angle increment, number of frames, and length of shoot.)

Instead, MSM has focused the Nomad on being just a star tracker, and I think wisely so. Its only controls are a three-position S-OFF-N switch, for using the Nomad in either the southern or northern hemisphere. It worked very well “Down Under,” with the exception noted below.

There is no solar or lunar drive rate, unnecessary in a tracker, and also no half-speed rate for nightscapes, used to lessen star trailing while also minimizing ground blurring. I’ve never liked using trackers at such a compromise half-speed rate, so I don’t miss it.

Using the optional V-Plate described below, I have used the Nomad to take tracked Milky Way panoramas, as shown here. It has worked very well for that purpose, with it easy to switch the tracking on (for the sky) and off (for the ground).

This is a 200° panorama of the arch of the northern Milky Way rising over Dinosaur Provincial Park, Alberta. Shot with the Nomad, with a blend of an untracked panorama for the ground and tracked panos for the sky.

The gear used to take the panorama above, including the Alyn Wallace V-Plate, supporting an Acratech 2-axis pan head. The Nomad is ON here, set to N. Below the power switch is the USB-C port for charging and external power.

My only criticism is that the power switch is a little mushy and perhaps easy to slide on by mistake when it is packed in a bag.

An LED for each of the N and S directions glows red to indicate the power is on and the direction chosen, handy to help prevent you from choosing the wrong direction by mistake.

The Nomad is powered by an internal lithium battery that charges from any 5-volt USB charger (the Nomad comes with a USB-C cord, but no charger). The Nomad takes about 2.5 hours to charge to full and runs for 6 to 7 hours of continuous tracking at room temperatures. A second LED by the USB port glows yellow when the Nomad is charging, and green when it has fully charged.

In practice the Nomad has lasted for several nights of shooting on one charge. When the battery level is low, the red LED for the other direction begins blinking. As a backup in the field, the Nomad can be powered via its USB-C port by any external 5-volt power bank.

Collisions

The Nomad hasn’t been without issues, though the main problem I’ve had I can’t, in fairness, blame on the Nomad.

Due to the Nomad’s small size and shape, ball heads sit close to the Nomad body. Locks and clamps sticking out from ball heads can collide with the Nomad, or with the Benro head, as it rotates the ball head. Here I show how a collision can occur when aimed up at the zenith.

Showing the ball head colliding with the Benro when aimed high.

But collisions can also occur when aimed at the Celestial Pole. I ran into that issue in Australia, where many of the wide-field targets in the Milky Way (such as the field in Carina and Crux shown earlier) lie close to the South Celestial Pole.

A camera aimed toward the Celestial Pole (either South or North) is more likely to collide with the Nomad than when a camera is aimed toward the sky opposite the Pole.

As I show above, one night when tracking targets in Carina I found the ball head had jammed against the Nomad, seizing its motion. As I feared, that caused something inside the Nomad to come loose.

After the collision incident no frame was well-tracked. The Nomad was wandering all over the place!

From then on it failed to track well for any shots. The drive was wobbling the stars in random directions. No frame was usable. The Nomad was now out of commission, not a welcome prospect when you have traveled to the other side of the world to shoot the sky.

The access hole with a handy adjustment screw that fixed the issue.

What was the solution? There was only one point of adjustment accessible to users, a mysterious hole on the side of the tracker with a small hex screw at the bottom. This is normally covered by a rubber plug, though that was either missing on arrival or got lost along the way from my unit. Upon inquiry, MSM told me the screw is for use just at the factory, for a final adjustment of the gear and bearing distance.

But in my case, tightening it slightly seemed to do the trick, restoring normal tracking. However, my unit still tends to make intermittent clicking sounds now and then, though it seems to track well enough again.

The lesson here is don’t let gear collide with the Nomad. It likely has no internal clutch, making it unforgiving of being jammed.

Collision Avoidance

How do you avoid collisions? What I should have used in Australia was MSM’s optional V-Plate designed by the late and sadly missed Alyn Wallace.

I bought one a couple of years ago, but never thought to bring it with me on the Australia trip. As I show above, the V-Plate allows for much more freedom to aim a camera, either toward the Poles or straight up (as I show above), or low in the sky 180° away from the Pole, without fear of the ball head hitting other components.

The V-Plate’s shortcoming is that, despite cranking down the levers that hold it in position, it can still slip under the weight of a heavy camera sitting on the diving-board-like platform supported only on one end. The V-Plate’s locks are not as solid and secure as they should be. But with care it can work well. And you need buy only the V-Plate; not the Z-Plate.

I should note that since I got my V-Plate, it has been upgraded with a larger lever handle to aid tightening the tilt lock. However, it really needs another support point on the tilt adjustment, so it can’t move as readily under load.

V-Plate lock knob hard to get at and adjust

In addition, MSM now offers a taller Arca-Swiss mounting block as an option, to replace the plate that comes bolted onto the Nomad with two Torx screws. That optional riser block moves the Nomad farther from the Wedge or Benro head, helping to prevent some collisions. By putting more space between the Nomad and the Benro head, the riser block makes it easier to get at the small locking clamp on the V-Plate’s rotation axis. But …

Shortly after I first published this review, a loyal reader (thanks, John!) pointed out his method of placing the Nomad on the Benro, with the Nomad turned 90° to the way I pictured it earlier. As I show below, this places the Benro’s lock knob on the side of the Nomad, not back. The benefit is that the V-Plate’s azimuth lock lever is now more accessible and well-separated from the Benro. That method makes the taller riser block unnecessary.

Here’s a reader-suggested alternative method for mounting the Nomad and orienting the Benro head that puts more space between the V-Plate and Benro, for ease of adjustment.

Even with this alternative method, the V-Plate tends to block the laser’s beam, as does a camera once it is mounted. The polar scope can also be blocked. It’s an example of how one MSM accessory can interfere with another accessory, perhaps requiring yet another accessory to solve!

Laser beam hitting the V-Plate with it horizontal

In practice, with the V-Plate installed, polar alignment often has to be done before attaching the camera or setting up the V-Plate to the desired orientation. When adding the camera, care has to be taken to then not bump the Nomad off alignment. That’s why I like the Benro head as a stable platform for the Nomad, despite its extra weight.

As I illustrated earlier, the V-Plate is also an essential accessory for shooting tracked-sky Milky Way panoramas, as it allows a camera to be turned parallel to the horizon from segment to segment while it also tracks the sky.

A “deepscape” of the Sagittarius starclouds over Mt. Blakiston, in Waterton Lakes National Park, Alberta. This is a blend of two exposures: a single untracked 2-minute exposure at ISO 1600 for the ground, and a single tracked 2-minute exposure at ISO 800 for the sky, taken immediately after, with the Nomad tracker motor now on. With a 28-70mm lens at 70mm, on the rig shown.

Recommendations

So, as with the Rotator, when buying a Nomad, plan on adding several “optional” accessories to your cart. They can, in fact, be essential.

However, they can add another $150 (for V-Plate + Wedge + riser block) to $250 (V-Plate + Benro head + riser block) to the total. These are in addition to the cost of the polar alignment aids offered in the various Basic bundles. I like having both the laser and polar scope, but for shooting just wide-angle nightscapes, the laser alone will do.

The cost of accessories makes the Nomad not quite the low-cost tracker you might have been sold on, nor as self-contained and compact as it first appears. Just choosing what combination of gear to buy can be daunting for beginners.

The Milky Way and its core region in Sagittarius and Scorpius over the Badlands of Dinosaur Provincial Park, Alberta. This is a blend of untracked exposures for the ground and tracked exposures for the sky, with the Canon Ra on the Nomad, with the Canon RF15-35mm lens at 20mm at f/2.8.

But when well-equipped, the little Nomad can work very well. Despite my run-in with a collision glitch, I can recommend the Nomad as a good choice for anyone looking for a solid, accurate, but portable tracker that can slip into any camera bag.

Just make room in your bag – and budget! – for polar alignment aids, V-Plates, wedges, and ball heads to complete your tracking kit.

And then don’t let anything collide with the Nomad!

— Alan, June 27, 2024 – Revised June 28 / AmazingSky.com

May 29, 2024May 29, 2024

Testing AI Noise Reduction Software for Astrophotography

AI-based noise reduction programs continue to improve, to provide remarkable results on many images. But … how well do they work on star-filled astrophotos?

In late 2022 I published a comparison of noise reduction programs current at that time. It’s here on my Amazing Sky blog.

As we know, software evolves rapidly. So here’s my latest look at versions of those programs current of as May 2024, plus new entries into the category, all with a focus on how well they perform on a variety of astrophotos. Only two programs tested here, NoiseXTerminator and GraXpert, are specifically designed to be used on astrophotos, primarily telescopic images of deep-sky objects.

The other programs on test are general purpose, for use on noisy images such as wildlife photos shot at high ISOs to freeze motion, or any photos shot under low light. But the latter includes nightscapes.

I tested programs in three categories, defined primarily by how they are used in a processing workflow:

General programs usable only on Raw files at the start of a workflow:

Adobe DeNoise AI from within Adobe Camera Raw (v16.3) or Lightroom (v13.3)
DxO PureRAW 4 (v4.1), a stand-alone app only

General programs usable as stand-alone apps on Raw files, but also as plug-ins for Photoshop for use later in a workflow (I tested both workflows):

Luminar Neo (v1.19.1) and its Noiseless AI filter
ON1 NoNoise AI 2024 (v18.3)
Topaz Photo AI (v3.02)

Programs specialized for astro work:

RC-Astro NoiseXTerminator (v1.1.3), usable only as a Photoshop plug-in
GraXpert (v3.0.2), usable only as a stand-alone application

(The latter two can also be installed as “processes” accessed from within the specialized astrophoto program PixInsight; I did not test that workflow.)

Comparing ACR’s standard noise reduction to 5 AI-based noise reduction programs

MY METHODS (“BUT WHAT ABOUT …?”)

I tested the five general-purpose programs on four types of astrophotos:

Nightscapes
Aurora images
Total solar eclipse images
Deep-sky images, both wide-field and telescopic

I tested the two specialized programs only on sample deep-sky photos, the types of images they are designed and trained for.

In all cases, the test images are single frames. I did not stack any images for these examples, as I wanted to show what the programs could do with noisy originals.

I tested only on Raw files from mirrorless cameras. I did not test on FITS files from specialized cooled astronomy cameras, as those require a quite different workflow and software.

Anticipating the “What about …?” question — no, I did not test Topaz DeNoise AI. While popular among astrophotographers, both it and its companion program, Sharpen AI, were discontinued in 2023, in favor of Topaz concentrating on their single program, Photo AI, that can de-noise, sharpen, and upscale.

I also did not test other Raw developer programs that contain noise reduction panels. (For example, DxO PhotoLab includes a version of PureRAW, and ON1 PhotoRAW contains a version of NoNoise.) For my most recent comparison of those programs see my test from January 2023.

I made an exception for Luminar Neo. While it includes general processing functions, it is used more often (certainly by me!) just as a plug-in for its AI-driven effects and filters, noise reduction being one.

PLEASE NOTE:

All the test images are full-resolution JPGs (6,000 to 8,000 pixels wide) that you can download (by right-clicking) for detailed inspection. You will often need to do so, to see the pixel-level differences I refer to.
But the sizes of the images make the blog page slow to load initially. Patience, please!
All images are © Alan Dyer, so any publication or posting elsewhere requires my permission, please and thank you! Just link to this blog if you wish to share the review.

DxO PureRAW can be called up from within Adobe Bridge by going to File>Open With … and choosing DxO PureRAW.

In Lightroom, the route to send images to PureRAW is File>Plug-In Extras>Process and Preview with DxO PureRaw 4. You cannot choose Photo>Edit In … as you might do to send images to other programs.

TL;DR SUMMARY (with links to the software websites)

Of the two Raw-only programs, Adobe’s DeNoise AI and DxO’s PureRAW 4, both worked well, with v4 of PureRAW much improved over its earlier artifact-prone v2 I tested and dismissed in 2022. Similarly, unlike its early version, Adobe DeNoise AI did not invent structures, such as auroral arcs.

Adobe’s DeNoise AI brought out details in the shadows much better than DxO’s PureRAW 4, which blocked up shadows. But PureRAW produced sharper details in illuminated landscapes, yielding less of the plastic appearance that Adobe DeNoise is still prone to. However, both programs turned star trails into wiggly worms.

Each of the three other general-purpose programs failed as stand-alone apps when importing Raw files, then exporting them as either Raw DNG (Digital Negative) files (ON1 NoNoise AI and Topaz Photo AI), or as TIFF files (Luminar Neo). Their exported images were either dark, vignetted, or hugely shifted in color or tonal balance. Results with that Raw-to-DNG/TIFF workflow were often unusable.

However, the same three programs (Luminar Neo, ON1 NoNoise AI and Topaz Photo AI) worked well as plug-ins from within Adobe Photoshop. Images now looked fine, with ON1 NoNoise producing what I thought was the best overall noise reduction with the fewest artifacts and “patchiness” in most examples. Luminar Neo’s Noiseless AI was consistently the poorest performer in all cases. It’s the program I can rule out of the running for noise reduction.

The two specialized astro programs, NoiseXTerminator and GraXpert, did a fine job on deep-sky images, reducing fine-grained noise without eliminating stars, just what they are “trained” to do. However, I felt NoiseXTerminator did the better job, with the new (as of May 2024) GraXpert 3.0 softening stars or leaving residual mottled artifacts. Neither worked well on nightscapes — while they didn’t harm detail too much, other programs performed better on what are often detailed but dark and noisy foregrounds.

My main takeaway — No one piece of AI software works best on all astrophotos. A program that provides great results on one image or class of image might perform poorly on another image. That’s the nature of AI-driven processing.

So … my overall conclusion and personal workflow picks? —

Adobe DeNoise AI would be my first choice for noisy nightscape images, where it has to be applied early in the workflow. It will be worth trying on deep-sky images.
DxO PureRAW might work better on some nightscapes with lots of ground textures.
ON1 NoNoise AI works well on many images when applied as a plug-in later in the workflow, but its sliders often need adjusting from the defaults.
NoiseXTerminator remains my preferred plug-in for deep-sky images.

PLEASE NOTE:

I have not provided prices and explained buying options, as frankly some can be complex!
For those details, go to the software’s website by clicking on the links in the names above. With the exception of Luminar Neo, all are available as free trial copies.
All programs are available for Windows and MacOS. I tested the latter versions, on an M1 Max MacBook Pro.

A typical test image, showing the small section that the comparison examples zoom in on. This is the first image shown below in detail.

RAW-ONLY PROGRAMS — NIGHTSCAPES

To provide evidence for my conclusions, I focus first on the two Raw-only programs, Adobe DeNoise AI and DxO PureRAW 4, as they produced by far the best results of all the programs on demanding nightscapes, often remarkably so. They not only reduce noise, they also recover fine details with AI sharpening you cannot turn off. How well that works is what I demonstrate below.

In each of the following examples, I show the two programs compared to an image processed in Adobe Camera Raw (ACR) using the Detail panel’s old non-AI adjustments for sharpening and noise reduction.

I developed all the images in ACR, then sent them through Adobe’s DeNoise AI option or into DxO PureRAW. Both options produce new raw DNG files, with all the develop settings intact and accurate, with some exceptions with PureRAW as shown below.

Peyto Lake Nightscape

Peyto Lake corner closeup — with Canon R5 at ISO 3200

In most cases I show only a section of images blown up by 250% to 500%. Here, in the first example of a nightscape shot I zoom in on a corner, as illustrated above, where noise often lurks due to lens vignetting. (I shot this and many of the nightscape examples with the 45-megapixel Canon R5. See my test of it for astrophotography here.)

The standard ACR noise reduction leaves a blizzard of fine noise and large color blotches. The Adobe DeNoise AI version (with it at 60%, the setting I used for all the DeNoise images) shows much less noise and somewhat reduced color blotches. The PureRAW version shows even better noise reduction, but the trees turn very dark with no detail.

But compare the mountainside. Adobe turns the rock layers into artificial-looking ropey bands; PureRAW’s detail recovery looks much more natural for texture.

Lake Edith Nightscape

Lake Edith corner closeup — with Canon R5 at ISO 5000

In this example, I again zoom in on a badly underexposed corner. The standard ACR version looks awful, riddled with color splotches and banding. The Adobe DeNoise version has cleaned up most of the mess. But the PureRAW version is better, eliminating even more noise and artifacts.

So is PureRAW better? Not so fast!

Storm Mountain Nightscape

Storm Mountain corner closeup — with Canon R5 at ISO 100

In this close-up of the Storm Mountain twilight image (that I show in full farther down the page), the normal image shot at ISO 100 isn’t marred too much by noise. But it does exhibit the magenta discoloration often seen in underexposed frame corners when the shadows are “lifted” brighter, as I show in the inset of the Basics panel.

The Adobe DeNoise version automatically corrected the color back to normal (I made no manual adjustments) and brought out the fine details. By comparison, PureRAW turned the trees completely dark, a lazy way to reduce noise! I tried further lifting the shadows with some reverse vignetting (as shown), but the result was a muddy mess. PureRAW crushed the shadows to the point no detail was recoverable.

So is Adobe better? Not necessarily ….

Lake Louise Nightscape

Lake Louise close-up — with Canon R5 at ISO 1600

Here I zoom in on famous Mount Victoria at the end of Lake Louise in Banff, in a one-minute exposure taken for the ground. As before, I think PureRAW has done a better job at recovering details in the mountain, though maybe to the point of over-sharpening? Adobe DeNoise perhaps looks more natural here.

But look at the star trails, which we sometimes want in our nightscapes, or have whether we want them or not! Yes, the sky in the AI-processed images looks less noisy, but the star trails now look like wiggly irregular streaks. PureRAW is a little worse, but both programs suffer from the same AI misinterpretation of the content. Both ruined the sky.

Will this always be the case?

Sierra Cabins Nightcape

Sierra Cabins close-up — with Fuji GFX100S at ISO 3200

All the other image examples are from Canon mirrorless cameras: the EOS R, Ra or R5. But this is a blow-up of a 100-megapixel photo from a medium-format Fuji GFX100S. The rustic cabin and the sky is less noisy in the AI images, with PureRAW the better performer here by a small margin. Stars look fine, and the AI sharpening of both programs has brought out the faint stars without any artifacts, a welcome improvement I think.

RAW-ONLY PROGRAMS — AURORA

I include this as a separate example, as an aurora photo provides a sky with a different type of content. In the past I’ve seen Adobe AI invent aurora rays.

Aurora Curtain

Aurora close-up — with Canon Ra at ISO 1600

This is an image from the Great Aurora show of May 10, 2024. There’s less noise in the AI versions of this example, and both programs also eliminated the errant hot red pixel at lower right in the ACR image. I’ve found these two AI programs can correctly identify and eliminate some hot pixels, though hot pixel removal can be hit or miss.

In all, I found the AI routines of Adobe and DxO did a fine job on auroras, reducing noise without introducing artifacts such as banding or posterized color gradations. Neither overly sharpened foreground details, nor added structures into the aurora or clouds that shouldn’t be there or that look unrealistic.

RAW-ONLY PROGRAMS — SOLAR ECLIPSE

Many of us have close-ups of the April 8, 2024 total eclipse of the Sun. Even though you might have shot them at a low ISO (even when eclipsed, the Sun is bright), you might have been surprised to see how much fine noise remains in the corona and sky.

Solar Eclipse Corona Close-Up

Corona close-up — with Canon R5 at ISO 100

This is a close-up of a frame taken through a 105mm f/6 refractor at a focal length of 630mm. Even at ISO 100, there’s a pixel-level granulation visible, but in this case I don’t think either Adobe DeNoise or PureRAW provided much of an improvement, likely because this is a low-ISO original.

In fact, I think Adobe DeNoise AI made noise worse, as its inherent sharpening added some dark flecks throughout the corona. But neither program introduced any banding, unlike Topaz was guilty of below.

RAW-ONLY PROGRAMS — DEEP-SKY

Here I compare the two Raw-only programs on several examples of deep-sky images — photos of the Milky Way and nebulas taken with tracking mounts so the stars remain pinpoints, ideally! These examples are tough tests, as the AI models have likely received little training on what these are supposed to look like! And faint stars can look like noise.

Orion Portrait

Orion close-up — with Canon Ra at ISO 800

First is a wide-angle portrait of Orion, blowing up the center of a tracked exposure with a 28-70mm zoom lens set to 46mm. (See my test of Canon RF zoom lenses here.) Shot at ISO 800, low for deep-sky images, this single frame is fairly clean to begin with. The AI programs do smooth the noise, without wiping out stars. Nice!

But they do accentuate the residual chromatic aberration (the blue haloes) on stars. PureRAW looks a little worse as it seems to have shifted the color to more magenta. All three Raw files have identical settings and profiles applied, yet PureRAW looks slightly different.

Cygnus H-alpha Monochrome

Cygnus close-up — with Canon Ra at ISO 3200 with Astronomik 12nm H-a clip-in filter

This is a more demanding example, shot with the same lens but at 70mm, and with the red-sensitive Canon Ra. It is rendered in monochrome as it was shot through a deep-red hydrogen-alpha filter to isolate the red light from the nebulas, here in Cygnus.

This is a single frame (you would normally stack lots of these!), very noisy due not only to the high ISO used, but also because only the red pixels (one quarter of the total on the sensor) recorded any signal.

Both Adobe DeNoise AI and DxO PureRaw have cleaned up the noise well. PureRAW has added more sharpening, tightening the stars and enhancing fine structure. Whether this is good or not depends on your goals and tolerance for AI-induced changes. In this case, I don’t think it has invented details.

But then there’s this example ….

Vela Supernova Remnant

Vela SNR close-up — with modified Canon R at ISO 3200

This, too, is a filtered single frame, taken through a 61mm-aperture telescope equipped with a “dual narrowband” filter which isolates the red H-alpha wavelength, but also the cyan Oxygen emission lines prominent in supernova remnants like this one in Vela. The deep filter requires shooting at a high ISO. So there’s lots of noise.

In this trio, I also applied NoiseXTerminator to the left image, an AI-based noise reduction program designed for just such images. I show more examples with “NoiseX” at the end.

I don’t think Adobe DeNoise or PureRAW have done any better job than NoiseX at reducing noise. If anything, each might have added some additional texturing that looks artificial, and accentuated chromatic aberration haloes on the stars. NoiseX wins here, right?

Well … look at the fine structures of the wisps of nebulas in all three panes. In the two panels at center and right, you can see more structure in the nebulosity, such as the protruding red fingers at top, that are not there in the NoiseX version at left. Is this real? Might other sharpening routines later in the workflow have brought it out anyway? Or are these details the products of AI imagination!?

Before purists dismiss the Adobe and DxO AI programs for fabricating details, here’s another example.

Crab Nebula

This is another supernova remnant, the famous Crab Nebula in Taurus. It is a 500% blow-up of the center of a single exposure with a modified Canon R on a 120mm f/7 refractor.

In this case, the “normal” image on the left has had just ACR’s old-style noise reduction applied, nothing else. In the middle and on the right, the Adobe and DxO AI versions are noticeably less noisy.

But … the small red tendrils are also more obvious with AI enhancement — and they are real (as comparisons to other more detailed astrophotos showed me). So here the AI has helped bring out subtle details while smoothing noise. I think PureRAW has sharpened stars a little too much, and shifted the colors, again to magenta.

Summary Points:

Both Adobe DeNoise AI and DxO PureRAW 4 can work wonders on nightscapes…
… Except on star trails! Both programs ruin star trails.
Their improvements to low ISO images is not so great, if minimal.
In its conversion of Raw to DNG, PureRAW sometimes introduced minor and unwelcome changes to images’ brightness and color. Adobe DeNoise did not.
But PureRAW recovered details in textured landscapes much better than DeNoise, which can suffer from plastic looking artifacts.
Both programs are worth trying on deep-sky images, if your workflow allows working with Raw files.
But you have to look carefully at the details – pixel peep! – as you might see oddities introduced by either program that you feel are unacceptable. Or you might see welcome sharpening, saving you more work later in processing.

Recommendations:

Adobe DeNoise AI has the advantage that if you are an Adobe Cloud subscriber you already have it. It is included with Lightroom and Camera Raw. So try DeNoise AI; you might like the results. Or not! But as with DxO PureRAW, it can be applied only to Raw files and only at the start of a workflow.
Download the trial copy of DxO PureRAW and test it on your own images. You might prefer it in your workflow.

OTHER PROGRAMS — WORKING STAND-ALONE ON RAW FILES

Now I test Luminar Neo Noiseless AI, ON1 NoNoise AI, and Topaz Photo AI — three AI noise reduction programs that can work not only on Raw files but on other file formats, allowing them to be applied at various points in a workflow.

All three programs can read Raw files from a wide range of cameras. Like PureRAW, ON1 and Topaz can also export DNG files, Adobe’s universal version of a Raw file. The best format Luminar can export to is a 16-bit TIFF.

I sent all the raw images I’ve shown above, plus a dozen more I’m not showing, through all three programs working as stand-alone apps, similar to how PureRAW operates. I usually applied their default or auto settings for noise reduction, and also for sharpening, as both Adobe and DxO also sharpen — you can’t have them not sharpen. I wanted to compare like to like.

Aurora Curtain

The exported files from all three programs showed noticeable differences in brightness and color on this aurora example from the May 10, 2024 display. Again, all have had the same develop settings applied to them as were applied to the original file in Camera Raw. Topaz shows over-sharpening, but that can be turned down from the usually excessive level chosen by its “Auto Pilot” routine.

Aurora over House

Another aurora example also shows significant differences in brightness, color and contrast. Auroras are particularly sensitive to shifts in white balance and to the camera profile chosen. In this case the profile was Camera Neutral. Only Luminar honored that profile; ON1 and Topaz offered only a generic Color profile in their DNGs. Luminar did not apply the lens correction for the Venus Optics 15mm lens used here, as it was not in its database. So its image looks dark and vignetted, requiring manual adjustments.

Peyto Lake Nightscape

The differences became even more marked on some of my test nightscapes. In this ISO 3200 Canon R5 image from Peyto Lake in Banff only Topaz’s exported DNG succeeds in resembling the original developed Raw file from ACR. Luminar’s TIFF is far too dark and ON1’s DNG is way too bright and contrasty. What happened there?

Storm Mountain Nightscape

Storm Mountain twilight scene with three programs as stand-alone apps

Another example, shot at ISO 100 with the Canon R5, also shows major disparities between the original Raw files and the exported images, with Luminar’s now looking the closest, ON1 still too bright and contrasty, and Topaz’s way too dark. There is no predicting what you’ll get.

I think the differences might be due to how each program interprets the camera profile used, but the reason is a mystery.

Summary Points:

Unlike DxO PureRAW 4, none of these three programs can be used in practice as stand-alone noise reduction apps, at least not with reliable results.

Recommendations:

Use Luminar Neo, ON1 NoNoise AI and Topaz Photo AI only as plug-ins, at least for noise reduction. That’s what I test next.

THE SAME TRIO — AS PLUG-INS WITHIN PHOTOSHOP

Thankfully, when I used the same three programs called up from within Photoshop as filter plug-ins, all worked well, though with varying levels of noise reduction quality.

All three can also be called up from within Adobe Lightroom.

Sending images to Plug-Ins with Lightroom, using Edit in ….

However, for the latter, do not use the route I advised at the beginning for DxO PureRAW. Do not send images to them via File>Plug-In Extras …. While that will work, you’ll get the same bad results I show in the previous section when using the programs as stand-alone apps.

Instead, as I show immediately above, from Lightroom, use Photo>Edit In… and choose your plug-in. That will produce the same good results I show below.

An even better method is to choose Photo>Edit In>Open as Smart Object in Photoshop. You can then apply these or any plug-in as a non-destructive “smart filter,” with settings you can re-adjust at any time, rather than being “baked into” the resulting TIFF file. That’s what I did for the tests below.

I can hear the anti-Adobe faction clamouring! For those who do not use Photoshop, all three programs will also install as plug-ins into Affinity Photo 2, a very Photoshop-like layer-based editor available under a perpetual license at low cost. However, I did not test that workflow variation.

Peyto Lake Nightscape

Peyto Lake close-up — with Canon R5 at ISO 3200

Here, on blow-ups of a noisy frame corner, I show the settings I used. Most are default, except for ON1 where I backed off its Tack Sharp Deblur from the 100 it had picked. While ON1 NoNoise ostensibly has an Auto function for detecting and applying an amount of noise reduction and sharpening suitable for each photo, it often picks 100%.

However, ON1 NoNoise AI did the best job. Topaz Photo AI still left noise in the foreground. Luminar Noiseless AI wasn’t bad, but left a noisier sky with some patchy artifacts.

Aurora Curtain

On the aurora example, I also applied Photoshop’s old Reduce Noise filter to the image brought in from Camera Raw. It can do a good job smoothing fine-scale noise.

With that conventional filter applied I found there wasn’t a big difference among the four versions. The three AI programs did a good job, with ON1 and Topaz better than Luminar, which still left some noise. Topaz over-sharpened the stars and trees, leaving colorful ringing artifacts on the latter. And that was with its Sharpen filter backed off to 30 from the 50 the Auto Pilot routine suggested using.

Vela Supernova Remnant Deep-Sky

Luminar Noiseless AI improved this noisy frame by only a small degree. ON1 and Topaz were much better, providing good noise reduction without adding significant artifacts or odd “invented” structures. As usual, Topaz sharpened stars by default, and perhaps a little too much.

Cygnus Starfield Deep-Sky

Cygnus close-up — with Canon Ra at ISO 1600

This star-rich field taken with a 70mm lens tests how well the programs can retain tiny stars while smoothing noise. Luminar left stars intact but didn’t provide much better noise reduction over what Camera Raw’s old manual noise sliders produced.

ON1 did provide a smoother background sky. But retaining faint stars required backing off Luminance noise reduction and increasing Enhance Detail to bring back the faint stars it wiped out with its default settings. Boosting Deblur and Micro Contrast can add ugly haloes on stars. So, with a deft touch to the sliders the results with ON1 can be very good, with the added benefit that it appears to reduce residual chromatic aberration around stars without affecting star colors.

With Topaz, sliding up Original Detail helped bring back stars lost to noise smoothing. However, there was an odd general reduction in contrast over the image.

Solar Eclipse Corona Close-Up

Each program handled this low-ISO file a little differently. Luminar seemed to actually increase noise, adding coarser structures and some banding. ON1 was the smoothest, with noticeably less noise than the original Camera Raw image. Topaz left (or added?) some fine scale color noise. It sharpened the lunar limb very well, though with a slight dark halo.

But the real revelation was when I zoomed out to look at the darker sky beyond the brightest parts of the corona.

Solar Corona Banding Artifacts

Corona sky close-up — with Canon R5 at ISO 100, showing Topaz banding artifacts

Topaz Photo AI introduced very noticeable banding in the form of square blocks, an artifact of how AI programs analyze images in “tiles.” I did see this in other photos processed with Photo AI, in areas that should look smooth. The culprit is the noise reduction; turn it off and the banding goes away, but now you have noise!

In this case, Topaz’s noise reduction ruined the image, though its sharpening was useful. Overall, I think ON1 NoNoise AI 2024 was the winning plug-in for noise reduction. But I’ve used Photo AI to sharpen solar prominences.

Summary Points:

All three programs worked well as plug-ins, with none of the extreme shifts in color or tone shown in the previous section in the stand-alone app exports.
However, even as a plug-in I felt Luminar Neo’s Noiseless AI filter consistently produced the worst results, or often little benefit at all.
Topaz Photo AI can produce good results, but watch for banding artifacts and over-sharpening. I also found that Topaz was prone to crashes and lock-ups, requiring force-quitting.
ON1 NoNoise AI 2024 provided the best overall noise reduction among these three plug-ins. The 2024 version is much improved over the 2023 version which had a High Detail mode that was awful! Even so, watch for loss of stars, or sharpening haloes. Play with the sliders.

Recommendations:

While Topaz Photo AI is popular among nature photographers, I would suggest ON1’s NoNoise AI 2024 is the better choice for astrophotographers looking for a noise reduction plug-in.
I can’t dismiss Luminar Neo. I like it for some of its other special effect filters, such as Orton glows, Magic Light, Sky Enhancer AI, and Accent AI. I find it a useful plug-in for effects and finishing touches. However, I would not recommend Luminar for noise reduction.

SPECIALIZED PROGRAMS — NOISE XTERMINATOR and GRAXPERT

No review of AI programs for astrophotography can leave out RC-Astro’s XTerminator plug-ins. Here I show Russell Croman’s NoiseXTerminator which uses AI trained on star-filled astrophotos. I tested it as a filter plug-in for Photoshop.

Also becoming popular in the last year is the free stand-alone application GraXpert. Developed first to eliminate nasty gradients of tone and color across deep-sky images due to light pollution, GraXpert now also includes AI-based noise reduction. I tested it as a stand-alone application; it does not install as a plug-in, though like NoiseXTerminator, it can install as a process accessible from within the popular astrophoto program PixInsight.

As a stand-alone app, GraXpert can only import and work on TIFFs, JPGs, or FITS files, the latter format produced by dedicated astro cameras.

I show only deep-sky image examples, as that’s the domain of these two programs.

Crab Nebula with NoiseXTerminator vs. ON1 and Topaz

First I show a comparison of the Crab Nebula test image with ACR’s standard non-AI noise reduction applied plus Photoshop’s old Reduce Noise filter. I compare this to the same image but with NoiseXTerminator also applied at 60% strength. Now compare this to versions with ON1 NoNoise and Topaz Photo AI.

NoiseXTerminator produced the smoothest result with no detrimental affect on the stars or nebulosity. ON1 is a good second place for noise reduction, with slightly sharper stars, which may or may not be desirable. Topaz produced subtle patchy artifacts and added tiny structures that may or may not be real.

NGC 1763 with NoiseXTerminator vs. ON1 and Topaz

NGC 1763 in LMC — with modified Canon R at ISO 3200

This is a single-frame close-up of the second best nebula in the Large Magellanic Cloud (after the Tarantula), taken at ISO 3200 through a dual-narrowband filter. So it is noisy.

The left panel is again with ACR and Photoshop’s Reduce Noise. But applying NoiseXTerminator cleaned the image up a lot. ON1 looks almost as good. Topaz sharpened detail to the point of revealing pinprick faint stars that are just blurs in the other images. These may indeed be real!

Vela Supernova Remnant with Noise XTerminator and GraXpert

The same Vela SNR image I used earlier shows excellent noise reduction from NoiseXTerminator, with star colors and nebula structures left alone. GraXpert at 50% strength (the developers have suggested backing off the settings) did not produce as smooth a sky. Applying GraXpert at 100% strength did yield noise reduction on par with NoiseX, but produced a slightly softer overall image.

Crab Nebula with Noise XTerminator and GraXpert

Processing the Crab Nebula image shows much the same results. Though I think here even at 100% GraXpert isn’t producing as good a level of noise reduction as NoiseX, leaving some patchiness amid the nebula, and a mottled texturing to the background sky.

Summary Points:

For the best noise reduction on deep-sky images, especially telescopic close-ups, the dedicated programs NoiseXTerminator and GraXpert trained on such images can do a better job than general-purpose AI programs.
I find NoiseXTerminator the better of the two, but GraXpert is new and evolving.

Recommendations:

GraXpert has the great benefit of being free! But on Macs it runs very slowly, something the developers admit and seem resigned to, as their market is Windows users. My test images each took 2 to 2.5 minutes to process, some 5 to 10 times slower than any of the other programs. And it runs only as a stand-alone app, yet it cannot read Raw files from DSLRs or mirrorless cameras, unlike PureRAW. But if you are a deep-sky imager, try it, as its main purpose – gradient removal – might prove indispensable.
As I prefer to accomplish as much of my editing as possible within one program, I prefer NoiseXTerminator as it can be applied from within Photoshop, and as an editable smart filter. I use it on most of my deep-sky images. I highly recommend it and RC-Astro’s other plug-ins.

YOUR MILEAGE MAY VARY!

The nature of AI means that results with any program can vary from image to image. That’s why no one, me included, can claim that one program is “the best!” Best for what? And with what workflow?

As some programs, such as Topaz Photo AI, offer multiple AI models and settings for strength and sharpening, results on the same image can be quite different. In most of my testing I used either the program’s auto defaults or backed off from those defaults where I thought the effect was too strong and detrimental to the image.

This is all by way of saying, your mileage may vary! In fact, it certainly will.

So don’t take my word for it. Most programs (Luminar Neo is an exception) are available as free trial copies to test out on your astro-images and in your preferred workflow. Test for yourself.

But do pixel peep. That’s where you’ll see the flaws. And the benefits. We are fortunate to have such a great arsenal of tools at our disposal. They will only get better as the AI models improve.

I hope my review – as lengthy as it is! – has helped you make an informed decision on what to buy.

— Alan, May 29, 2024 / AmazingSky.com

September 4, 2023September 5, 2023

Testing for the Annular Solar Eclipse

With the October 14, 2023 annular eclipse of the Sun only weeks or days away, it’s time to test your equipment, to ensure success on eclipse day.

On October 14 everyone in North America, Central America, and much of South America can see an eclipse of the Sun, as shown in the map below, courtesy GreatAmericanEclipse.com. The closer you are to the “path of annularity” drawn in yellow here, the more of the Sun you see covered by the Moon.

Eclipse map showing area of visibility of the October 14 eclipse courtesy GreatAmericanEclipse.com

However, for the best experience, plan to be in the central path of the Moon’s shadow. In North America, as shown in the map below, that path crosses the western states, passing over the scenic landscapes of the American southwest.

Those in the main path will see an annular eclipse – the Moon will travel across the center of the Sun’s disk, but won’t be large enough to completely cover the Sun. The result, as shown below, is that the Sun will be reduced to a thin ring or “annulus” of light at mid-eclipse, but only for a few minutes.

For details of when the eclipse occurs and how long the eclipse lasts at your site, see the interactive map at Fred Espenak’s site at https://www.eclipsewise.com/solar/SEgmapx/2001-2100/SE2023Oct14Agmapx.html

GEAR AND FILTERS

The May 10, 1994 annular eclipse of the Sun, with a trio of eclipse rigs.

To view or photograph the annular eclipse well, you need to use a long telephoto lens or a telescope. A focal length of 400mm or longer is required to make the Sun’s and Moon’s disks large enough to show detail well.

As I show above, the lens or telescope can be on a solid tripod, or on an untracked alt-azimuth telescope mount, or on a mount that can track the sky, such as the equatorial mount on the right above. All will work fine, as exposures will always be short, just a fraction of a second.

I go into the many options for photographing the eclipse in my ebook, linked to at right. It contains thorough tutorials on how to shoot the eclipses in 2023 and 2024. In this blog I’m focusing on extolling the need to practice now, with whatever gear you own and intend to use for the eclipse.

An array of solar filers, for unaided eyes, lenses and telescopes

No matter what optics you plan to use, they must be equipped with a safe solar filter mounted over the front of the optics. For the October 14 eclipse, even from sites in the path of annularity, a filter must be used at all times. It will never be safe to look at or shoot the Sun without a filter.

And it must be a filter dense enough and designed for the purpose of aiming at the Sun. Do not use stacked neutral density filters or other jury-rigged arrangements, as other filters can transmit ultraviolet or infrared light that can still damage eyes and cameras.

If you do not have a proper filter for your lens or telescope, get one now. Order from reputable suppliers such as AstroZap, Baader Planetarium, Kendrick Astro Instruments, Seymour Solar, Thousand Oaks Optical, or from the makers of telescopes and their dealers.

The eyeglass or handheld style of solar filters are good for unaided eye views, and most are made by American Paper Optics or Rainbow Symphony. A list of recommended filter suppliers is available at the American Astronomical Society’s eclipse website at https://eclipse.aas.org/eye-safety. In addition, many astronomy clubs, planetariums and science centers will offer safe eyeglass-style filters they purchased in bulk from one of the suppliers above.

However, for photography through a lens or telescope you need a filter that either screws onto the lens or clamps over the telescope, as I show below.

Comparing different types of telescope filters – the Baader Mylar worked best in this test.

In my testing, I’ve found that the aluminized Mylar® (or polyethylene) type of filter – one that looks like a silvery sheet – provides the best sharpness and contrast, despite the wrinkles. The most popular type is made by Baader Planetarium, and sold by them or by other dealers and resellers.

While metal-coated glass filters also work very well, in recent years they have become hard to find, with past suppliers of glass filters switching to black polymer plastic material. While safe and good for naked-eye views, I’ve found the image through black polymer filters can be soft and surrounded by lots of light scatter when used for photography at long focal lengths.

TESTING, TESTING!

An eclipse rig under test, with dual scopes for shooting and looking

Once properly equipped, test your setup as soon as possible on the Sun. In the rig above I have piggybacked a smaller telescope onto the larger telescope, both with filters, the latter to shoot through while I look through the smaller scope, good for watching the few minutes of annularity.

The key things to test for are:

Finding the Sun (not as easy as you might think!)
Focusing on the Sun (also critical and can be tough – focus on the edge or on sunspots)
Checking for any focus shift over a couple of hours time
Determining the correct exposures with your filter
Checking for any vibration that can blur the image
Operating your camera to change settings, without vibration
Checking to see how long batteries will last
Seeing how much the Sun moves across the frame during a few minutes time
Following the Sun or keeping it centered
Making a checklist of the gear you need on eclipse day, plus any backups such as a spare battery, and tools for last-minute fixes or adjustments.

The filters from Kendrick Astro Instruments have a handy Sun finder attachment.

You want to test how solid your setup is when aimed up. Your super-telephoto lens and tripod that work great for birds and wildlife might not be as well-suited as you thought when aimed high at the Sun. Best to find out now about any shortcomings in your gear.

A series of images with an 80mm refractor and Kendrick Mylar filter shows a range from under to over-exposed.

Run through a set of exposures to see what produces the best result with your optics and filter. Even with the October 14 eclipse underway, the Sun will be a similar brightness as it is on any normal day.

At best, on eclipse day you might wish to shoot a bracketed set of exposures throughout the eclipse, perhaps a frame taken at your pre-determined “best” exposure, and two others: at one stop and two stops overexposed, to account for the slightly dimmer solar disk when it is mostly covered by the Moon in a deep partial or annular phase.

Alter exposures by changing shutter speeds, not aperture or ISO. Keep the ISO speed low, and the aperture either wide open or at some middle setting such as f/5.6 for the sharpest images.

But also check what exposures might be needed when shooting the Sun through thin clouds. Any cloud or haze will require longer exposures. And you might need to change shutter speeds quickly if the Sun goes into and out of clouds. Practice that – without introducing vibration from handling the camera.

Leave the rig for a couple of hours to test how the focus might shift, as it is certain to do, as the temperature changes through the morning or afternoon. Practice touching up the focus. People fuss over the “best” exposure, when it is poor focus that is the common spoiler of eclipse photos.

You can find more tips for practicing for eclipse close-ups at a blog I wrote for AstronomyByNight.ca.

WIDE-FIELD OPTIONS

May 10, 1994 annular eclipse in a series of multiple exposures every 10 minutes.

An alternative way to shoot the eclipse is with a wide-angle lens, but also equipped with a solar filter, as shown above. Frame the scene to include the expected path of the Sun, determined by using planetarium software such as SkySafari or Stellarium (my ebook also has charts). Take images every minute or so, then layer those onto an unfiltered image of the sky and foreground taken either before the Sun enters the frame or after it leaves it.

Practice that method now, to shoot images for a test composition as I show above. It layers filtered images taken at 5-minute intervals onto an unfiltered background sky image taken after the Sun left the frame.

However, composite images can be complex to plan and execute.

The partial solar eclipse of October 23, 2014 as seen from Jasper, Alberta, at a public event in Centennial Park as part of the annual Dark Sky Festival. This is a single-exposure image showing the scene near mid-eclipse with telescopes from volunteers from the Royal Astronomical Society of Canada, and the mostly clear skies above with the crescent Sun visible through the handheld polymer solar filter.

A simpler method for grabbing a souvenir eclipse photo is to simply hold a handheld solar filter in front of the lens to dim the Sun but leave the rest of the scene visible.

Again, you can practice that now to see what exposure might be best. For this type of shot I find black polymer filters best as they are less reflective than the Mylar type.

That method, or using a long lens or telescope will work well on eclipse day no matter where you are, either in the path or elsewhere enjoying the partial eclipse, as in the example image below, also from October 23, 2014, shot with my small scope at lower left in the image above.

The partial eclipse of the Sun, October 23, 2014, as seen from Jasper, Alberta, shot under clear skies through a Mylar filter, on the front of a 66mm f/6 apo refractor.

No matter the method and gear you use, success on eclipse day will require practicing beforehand to learn what can go wrong, and what works best for the setup you plan to use. Never assume something will work!

Clear skies on October 14! The annular eclipse that day will serve as a great dress rehearsal for the big eclipse to come – the total eclipse of the Sun on April 8, 2024. That’s the event you really want to get right!

– Alan, September 5, 2023

January 1, 2023March 25, 2023

Testing Raw Developer Software for Astrophotography

I test nine programs for processing raw files for the demands of nightscape astrophotography.

Warning! This is a long and technical blog, but for those interested in picking the best software, I think you’ll find it the most comprehensive test of programs for processing nightscapes. The review is illustrated with 50 high-resolution, downloadable images which will take a while to load. Patience!

As a background, in December 2017 I tested ten contenders vying to be alternatives to Adobe’s suite of software. You can find that earlier survey here on my blog. But 2017 was ages ago in the lifetime of software. How well do the latest versions of those programs compare now for astrophotography? And what new software choices do we have as we head into 2023?

To find out, I compared eight programs, pitting them against what I still consider the standard for image quality when developing raw files, Adobe Camera Raw (the Develop module in Adobe Lightroom is essentially identical). I tested them primarily on sample nightscape images described below.

I tested only programs that are offered for both MacOS and Windows, with identical or nearly identical features for both platforms. However, I tested the MacOS versions.

In addition to Adobe Camera Raw (represented by the Adobe Bridge icon), I tested, in alphabetical order, and from left to right in the icons above:

ACDSee Photo Studio
Affinity Photo 2 (from Serif)
Capture One 23
Darktable 4
DxO PhotoLab 6
Exposure X7
Luminar Neo (from SkyLum)
ON1 Photo RAW 2023

I tested all the programs strictly for the purpose of processing, or “developing” raw files, using nightscape images as the tests. I also looked at features for preparing and exporting a large batch of images to assemble into time-lapse movies, though the actual movie creation usually requires specialized software.

NOTE: I did not test the programs with telescope images of nebulas or galaxies. The reason — most deep-sky astrophotographers never use a raw developer anyway. Instead, the orthodox workflow is to stack and align undeveloped raw files with specialized “calibration” software such as DeepSkyStacker or PixInsight that outputs 16-bit or 32-bit TIFFs, bypassing any chance to work with the raw files.

TL;DR Conclusions

Here’s a summary of my recommendations, with the evidence for my conclusions presented at length (!) in the sections that follow:

What’s Best for Still Image Nightscapes?

Adobe Camera Raw (or its equivalent in Adobe Lightroom) still produces superb results, lacking only the latest in AI noise reduction, sharpening and special effects. Though, as I’ve discovered, AI processing can ruin astrophotos if not applied carefully.

The Adobe alternatives that provided the best raw image quality in my test nightscapes were Capture One and DxO PhotoLab.

ACDSee Photo Studio, Exposure X7,and Luminar Neo produced good results, but all had flaws.

ON1 Photo RAW had its flaws as well, but can serve as a single-program replacement for both Lightroom and Photoshop.

Affinity Photo works well as a Photoshop replacement, and at a low one-time cost. But it is a poor choice for developing raw images.

If you are adamant about avoiding subscription software, then a combination of DxO PhotoLab and Affinity Photo can work well, providing great image quality, and serving to replace both Lightroom and Photoshop.

I cannot recommend Darktable, despite its zero price. I struggled to use its complex and overly technical interface, only to get poor results. It also kept crashing, despite me using the new ARM version on my M1 MacBook Pro. It was worth what I paid for it.

At the end of my blog, I explain the reasons why I did not include other programs in the test, to answer the inevitable “But what about …!?” questions.

What’s Best for Basic Time-Lapses?

For simple time-lapse processing, where the same settings can be applied to all the images in a sequence, all the programs except Affinity Photo, can copy and paste settings from one key image to all the others in a set, then export them out as JPGs for movie assembly.

However, for the best image quality and speed, I feel the best choices are:

Adobe, either Lightroom or the combination of Camera Raw/Bridge
Capture One 23
DxO PhotoLab 6

While ON1 Photo RAW can assemble movies directly from developed raw files, I found Capture One or DxO PhotoLab can do a better job processing the raw files. And ON1’s time-lapse function is limited, so in my opinion it is not a major selling point of ON1 for any serious time-lapse work.
Luminar Neo was so slow at Copy & Paste and Batch Export it was essentially unusable.

What’s Best for Advanced Time-Lapses?

None of the non-Adobe programs will work with the third-party software LRTimelapse (www.lrtimelapse.com). It is an essential tool for advanced time-lapse processing.

While ON1 offers time-lapse movie assembly, it cannot do what LRTimelapse does — gradually shift processing settings over a sequence based on keyframes to accommodate changing lighting, and to micro-adjust exposure levels based on actual image brightness to smooth out the bane of time-lapse shooters — image flickering.

LRTimelapse works only with Lightroom or ACR/Bridge. If serious and professional time-lapse shooting is your goal, none of the Adobe contenders will do the job. Period. Subscribe to Adobe software. And buy LRTimelapse.

Avoiding Adobe?

My testing demonstrated to me that for nightscape photography, Adobe software remains a prime choice, for its image quality and ease of use. However, the reasons to go with any program other than Adobe are:

For equal or even better image quality, or for features not offered by Adobe.
But mostly to avoid Adobe’s subscription model of monthly or annual payments.

Capture One pricing as of early 2023, in Canadian funds.

All the non-Adobe alternatives can be purchased as a “perpetual license” for a one-time fee, though often with significant annual upgrade costs for each year’s major new release. However, you needn’t purchase the upgrade; your old version will continue to run. Below, I provide purchase prices in U.S. funds, but most companies have frequent sales and discount offers.

While all of Adobe’s competitors will proclaim one-time pricing, several also offer their software via annual subscriptions, with additional perks and bonuses, such as file syncing to mobile apps, or better long-term or package pricing, to entice you to subscribe.

Keep in mind that whatever program you use, its catalog and/or sidecar files where your raw image settings are stored will always be proprietary to that program. ON1 and Affinity also each save files in their own proprietary format. Switch to any other software in the future and your edits will likely not be readable by that new software.

Raw Editing vs. Layer-Based Editing

As I mentioned, I tested all the programs strictly for their ability to process, or “develop,” raw image files for nightscapes. (Raw files are likened to being digital negatives that we “develop.”)

For some nightscape still images, raw developing might be all that’s needed, especially as software companies add more advanced “AI” (artificial intelligence) technology to their raw developers for precise selection, masking, and special effects.

In the case of time-lapse sequences made of hundreds of raw frames, raw developing is the only processing that is practical. What we need for time-lapses is to:

Develop a single key raw file to look great, then …
Copy all its settings to the hundreds of other raw files in the time-lapse set, then …
Export that folder of raw images to “intermediate JPGs” for assembly into a movie, usually with a specialized assembly program.

The programs that offer layer-based editing: Adobe Photoshop, ON1 Photo RAW, and Serif Affinity Photo

However, for most still-image astrophotography, including nightscapes, we often stack and/or blend multiple images to create the final scene, for several reasons:

To stack multiple images with a Mean or Median stack mode to smooth noise.
To layer dozens of images with a Lighten blend mode to create star trails.
To layer and blend images via masking to combine the different exposures often needed to record the ground and sky each at their best.
Or often as not, a combination of all of the above!

All those methods require a layer-based program. Adobe Photoshop is the most popular choice.

Of the programs tested here, only two also offer the ability to layer multiple images for stacks, blends and composites. They are:

Affinity Photo 2
ON1 Photo RAW 2023

I did not test these two programs to compare their image layering and masking abilities vs. Photoshop, as important as those functions might be.

Fans of Skylum’s Luminar Neo will point out that it also supports image layers. In theory. In the version I tested (v1.6.2) bugs made it impossible to load files into layers properly — the layer stack became confused and failed to display the stack’s contents. I could not tell what it was stacking! Skylum is notorious for its buggy releases.

Those determined not to use Adobe software should be aware that, apart from Affinity Photo and ON1 Photo RAW, all the other programs tested here are not replacements for Adobe Photoshop, nor are they advertised as such. They are just raw developers, and so can serve only to replace Adobe Lightroom or Adobe Camera Raw/Adobe Bridge.

The Challenge

This is the main image I threw at all nine programs, a single 2-minute exposure taken at Lake Louise, Alberta in October 2022. The lens was the Canon RF15-35mm at f/2.8 on a Canon R5 camera at ISO 800.

Above is the raw image as it came out of camera, with the default Adobe Color camera profile applied, but no other adjustments. The length of exposure on a static tripod meant the stars trailed. The image has:

A sky that needs color correcting and contrast enhancement.
Dark shadows in the foreground and distance that need recovery.
Bright foreground areas that need suppressing, where lights from the Chateau Lake Louise hotel illuminate the mountainsides and water.
Lens flares and lights from night hikers that need retouching out.

It is an iconic scene, but when shot at night, it’s a challenging one to process.

The untracked image developed in Adobe Camera Raw

Above is the image after development in Adobe Camera Raw (ACR), using sliders under its Basic, Optics, Detail, Curve, Color Mixer, and Calibration tabs, and applying the Adobe Landscape camera profile. Plus I added retouching, and local adjustments with ACR’s masks to affect just the sky and parts of the ground individually. This is the result I think looks best, and is the look I tried to get all other programs to match or beat. You might prefer a different look or style.

In addition, I tried all programs on another two-minute exposure of the scene (shown above) but taken on a star tracker to produce untrailed, pinpoint stars, but a blurred ground. It served to test how well each program’s noise reduction and sharpening dealt with stars.

The final layered and blended image in Adobe Photoshop

I shot that tracked version to blend with the untracked version to produce the very final image above, created from the Camera Raw edits. That blending of sky and ground images (with each component a stack of several images) was done in Photoshop. However, Affinity Photo or ON1 Photo RAW could have done the required layering and masking. I show a version done with Affinity at the end of the blog.

The Competitors

In a statement I read some time ago, DxO stated that Adobe products enjoy a 90% share of the image processing market, leaving all the competitors to battle over the remaining 10%. I’m not sure how accurate that is today, especially as many photographers will use more than one program.

However, I think it is fair to say Adobe’s offerings are the programs all competitors are out to beat.

NOTE: Click/tap on any of the images to bring them up full screen as high-res JPGs so you can inspect them more closely.

The Established Standard

Adobe Camera Raw (included with Photoshop, Adobe Bridge and Lightroom)

Cost: $10 a month, or $120 a year by subscription for 20 Gb of cloud storage (all prices in U.S. $)

Website: https://www.adobe.com

Version tested: 15.1

Adobe Camera Raw (ACR) is the raw development utility that comes with Photoshop and Adobe Bridge, Adobe’s image browsing application. Camera Raw is equivalent to the Develop module in Lightroom, Adobe’s cataloguing and asset management software. Camera Raw and Lightroom have identical processing functions and can produce identical results, but I tested ACR. I use it in conjunction with Adobe Bridge as an image browser. Bridge can then send multiple developed images into Photoshop as layers for stacking. All programs are included in Adobe’s Photo subscription plan.

The Contenders (in Alphabetical Order)

Here are the eight programs I tested, comparing them to Adobe Camera Raw. All but Skylum’s Luminar Neo offer free trial copies.

ACDSee Photo Studio

Cost: $100 to $150, depending on version. $50 on up for annual major upgrades. By subscription from $70 a year.

Website: http://www.acdsystems.com

Version tested: 9.1

I tested Photo Studio for Mac v9. Windows users have a choice of Photo Studio Professional or Photo Studio Ultimate. All three versions offer a suite of raw development tools, in addition to cataloging functions. However, the Ultimate version (Windows only) also offers layer-based editing, making it similar to Photoshop. ACDSee assured me that Photo Studio for Mac resembles the Windows Professional version, at least for basic raw editing and image management. However, Photo Studio Professional for Windows also has HDR and Panorama merging, which the Mac version does not.

Affinity Photo 2

Cost: $70. Upgrades are free except for rare whole-number updates (in seven years there’s been only one of those!). No subscription plan is offered.

Website: https://affinity.serif.com

Version tested: 2.0.3

Apart from the free Darktable, this is the lowest-cost raw developer on offer here. But Affinity’s strength is as a layer-based editor to compete with Photoshop. As such, Affinity Photo has some impressive features, such as the unique ability to calibrate and align deep-sky images, its stack modes (great for star trails and noise smoothing) which only Photoshop also has, and its non-destructive adjustment layers, filters and masks. Affinity Photo is the most Photoshop-like of all the programs here. However, it alone of the group lacks any image browser or cataloging function, so this is not a Lightroom replacement.

Capture One 23 Pro

Cost: $299. 33% off (about $200) for annual major upgrades. By subscription for $180 a year.

Website: https://www.captureone.com/en

Version tested: 16.0.1.17

Capture One started life as a program for tethered capture shooting in fashion studios. It has evolved into a very powerful raw developer and image management program. While Capture One advertises that it now offers “layers,” these are only for applying local adjustments to masked areas of a single underlying image. While they work well, you cannot layer different images. So Capture One cannot be used like Photoshop, to stack and composite images. It is a Lightroom replacement only, but a very good one. However, it is the most costly to buy, upgrade each year, or subscribe to, which appears to be the sales model Capture One is moving toward, following Adobe.

Darktable

Cost: Free, open source.

Website: https://www.darktable.org

Version tested: 4.2.0

In contrast to Capture One, you cannot argue with Darktable’s price! For a free, open-source program, Darktable is surprisingly full-featured, while being fairly well supported and updated. As with most free cross-platform programs, Darktable uses an unconventional and complex user interface lacking any menus. It has two main modules: Lighttable for browsing images, and Darkroom for editing images. Map, Slideshow, Print and Tethering modules clearly signal this program is intended to be a free version of Lightroom. The price you pay, however, is in learning to use its complex interface.

DxO PhotoLab 6 ELITE

Cost: $219. $99 for annual major upgrades. No subscription plan is offered.

Website: https://www.dxo.com

Version tested: 6.1.1

DxO PhotoLab is similar to Capture One in being a very complete and feature-rich raw developer with good image management functions and a well-designed interface. While it has an image browser for culling, keywording and rating images, PhotoLab does not create a catalog as such, so this isn’t a full Lightroom replacement. But it is a superb raw developer, with very good image quality and noise reduction. While PhotoLab is also available in a $140 ESSENTIAL edition, it lacks the DeepPrime noise reduction and ClearView Plus haze reduction, both useful features for astrophotos.

Exposure X7

Cost: $129. $89 for annual major upgrades. No subscription plan is offered.

Website: https://exposure.s o ftware/

Version tested: 7.1.5

Formerly known as Alien Skin Exposure, from the makers of the once-popular utilities Blow Up and Eye Candy, Exposure X7 is a surprisingly powerful raw editor (considering you might not have heard of it!), with all the expected adjustment options, plus a few unique ones such as Bokeh for purposely blurring backgrounds. It enjoys annual major updates, so is kept up to date, though is a little behind the times in lacking any AI-based effects or masking, or even automatic edge detection. Like Capture One, Exposure offers adjustment layers for ease of applying local edits.

Luminar Neo

Cost: $149. $39 to $59 for individual Extensions. $179 for Extensions pack. By subscription for $149 a year which includes Neo and all Extensions. Frequent discounts and changing bundles make the pricing confusing and unpredictable.

Website: https://skylum.com/luminar

Version tested: 1.6.2

By contrast to Exposure X7, Luminar Neo from Skylum is all about AI. Indeed, its predecessor was called Luminar AI. Introduced in 2022, Neo supplanted Luminar AI, whose image catalog could not be read by Neo, much to the consternation of users. Luminar AI is now gone. All of Skylum’s effort now goes into Neo. It offers the expected raw editing adjustments, along with many powerful one-click AI effects and tools, some offered as extra-cost extensions in a controversial à la carte sales philosophy. Neo’s cataloging ability is basic and unsuitable for image management.

ON1 Photo RAW 2023

Cost: $99. $60 for annual major upgrades. $70 for individual plug-ins, each with paid annual updates. By subscription for $90 a year which includes all plug-ins and updates.

Website: https://www.on1.com

Version tested: 17.0.2

Of all the contenders tested, this is the only program that can truly replace both Lightroom and Photoshop, in that ON1 Photo RAW has cataloging, raw developing, and image layering and masking abilities. In recent years ON1 has introduced AI functions for selection, noise reduction, and sharpening. Some of these are also available as individual plug-ins for Lightroom and Photoshop at an additional cost. While the main program and plug-ins can be purchased as perpetual licences, the total cost makes an annual subscription the cheapest way to get and maintain the full ON1 suite. Like Capture One, they are moving customers to be subscribers.

Feature Focus

I have assumed a workflow that starts with raw image files, not JPGs, for high-quality results. And I have assumed the goal of making that raw image look as good as possible at the raw stage, an important step in the workflow, as it is the only time we have access to the full dynamic range of the 14-bit raw data that comes from the camera.

I judged each program based on several features I consider key to great nightscapes and time-lapses:

Browser/Cataloging Functions —Because we often deal with lots of images from an astrophoto shoot, the program should allow us to sort, rate, and cull images before proceeding with developing the best of the set for later stacking, and to easily compare the results.

Lens Corrections —Does the program apply automatic lens corrections for distortion and vignetting? How extensive is its lens database? Or are manual adjustments required?

Noise Reduction —We shoot at high ISOs, so good noise reduction is essential for removing digital noise without sacrificing details such as pixel-level stars, or adding AI artifacts.

Shadow Recovery —While good highlight recovery can be important (and a prime reason for shooting and processing raw images), in nightscapes good shadow recovery is even more crucial. The starlit ground is dark, but rich in detail. We want to recover that shadow detail, without affecting other tonal ranges or introducing noise.

Local Adjustments and Masking —Good masking tools allow us to do more at the raw stage while we have access to the full range of image data. But how precise can the masks be? How easy is it to apply different settings to the ground and sky, the most common need for local adjustments with nightscapes.

Overall Finished Image Quality —Tools such as Dehaze and Clarity can work wonders at boosting contrast in the sky. Good color adjustments from HSL sliders can help fine-tune the overall color balance. How good did the final image look? — an admittedly subjective judgement.

Copy & Paste Settings —A program should not only develop one image well, but also then be able to transfer all of that key image’s settings to several other images taken for noise stacking, or to what could be hundreds of images shot for a time-lapse movie or star trail scene.

Batch Export —For stacking images for star trails, or for creating panoramas in advanced stitching programs such as PTGui, or when assembling time-lapse movies, the program should allow a “batch export” of selected images to TIFFs or JPGs for use elsewhere.

Advanced Features —Does the program support panorama stitching and HDR (High Dynamic Range) merging of selected developed raw files? If so, what type of file does it create?

Summary Comparison Table

• = Feature is present; ticks the boxes!

— = Feature is missing

Partial = Feature only partially implemented (e.g. Only has distortion correction but not vignetting correction, or has limited cataloging functions)

I judged other features on an admittedly subjective scale of Poor, Fair, Good, or Excellent, based on my overall impressions of the reliability, options offered, quality, and/or speed of operation.

Feature-by-Feature Details — 1. Browsing and Cataloging

Here, feature by feature, are what I feel are the differences among the programs, comparing them using the key factors I listed above.

All programs, but one, offer a Browse or Library module presenting thumbnails of all the images in a folder or on a drive. (For Adobe Camera Raw that module is Adobe Bridge, included with the Creative Cloud Photo subscription.) From the Browse/Library module you can sort, rate and cull images.

The Catalog screens from six of the programs tested

Luminar Neo’s Catalog function (as of early 2023) allows only flagging images as favorites. It is very crude.

The other programs have more full-featured image management, allowing star rating, color label rating, pick/reject flags, keywording, grouping into collections or projects, and searching.

Capture One and ON1 Photo RAW provide the option of importing images into formal catalogs, just as Adobe Lightroom requires. However, unlike Lightroom, both programs can also work with images just by pointing them to a folder, without any formal import process. Capture One calls this a “session.” Adobe Bridge works that way — it doesn’t produce a catalog.

While not having to import images first is convenient, having a formal catalog allows managing a library even when the original images are off-line on a disconnected hard drive, or for syncing to a mobile app. If that’s important, then consider Capture One, ON1 Photo RAW, or Adobe Lightroom. They each have mobile apps.

Adobe Lightroom (but not Bridge) is also able to connect directly to what it calls “Publish Services” — Flickr, PhotoShelter, and SmugMug for example, using plug-ins offered by those services. I use that feature almost daily. ACDSee offers that feature only in its Windows versions of Photo Studio. As best I could tell, all other programs lacked anything equivalent.

Serif Affinity Photo is the lone exception lacking any form of image browser or asset management. It’s hard to fathom why in late 2022, with their major update to Version 2 of their software suite, Serif did not introduce a digital asset management program to link their otherwise excellent Photo, Designer and Publisher programs. This is a serious limitation of Serif’s Affinity creative suite, which is clearly aimed at competing one-on-one with Adobe Photoshop, Illustrator and InDesign, yet Serif has no equivalent of Adobe Bridge for asset management.

WINNERS: Capture One and ON1 Photo RAW, for the most flexibility in informal browsing vs. formal cataloguing. Adobe Lightroom for its Publish Services.

LOSER: Affinity Photo for lacking any image management or catalog.

Feature-by-Feature Details — 2. Lens Corrections

The wide-angle lenses we typically use in nightscape and time-lapse imaging suffer from vignetting and lens distortions. Ideally, software should automatically detect the camera and lens used and apply accurate corrections based on its equipment database.

The Lens Corrections panels from all nine programs.

Of the nine programs tested, only four — Adobe Camera Raw, Darktable, DxO PhotoLab, and ON1 Photo Raw — automatically applied both distortion and vignetting corrections for the Canon RF15-35mm lens I used for the test images. DxO is particularly good at applying corrections, drawing upon the company’s vast repository of camera and lens data. If your local copy of PhotoLab is missing a camera-lens combination, what it calls a “module,” DxO allows you to download it or request it.

Capture One and Exposure X7 both detected the lens used and applied distortion correction, but did nothing to adjust vignetting. I had to apply vignetting correction, a more important adjustment, manually by eye.

ACDSee and Luminar have no Auto Lens Corrections at all; distortion and vignetting both have to be dialed in manually.

Affinity Photo lacked any automatic correction data for the Canon RF15-35mm lens in question, despite the lens being introduced in 2019. I selected the similar Canon EF16-35mm lens instead, as I show above circled in blue. Affinity gets marks off for having an outdated and incomplete lens database.

WINNERS: Adobe, Darktable, DxO PhotoLab, and ON1 Photo RAW, for full Auto Lens Corrections.

LOSERS: ACDSee and Luminar, for lacking Auto Lens Corrections.

Feature-by-Feature Details — 3. Noise Reduction and Sharpening

Absolutely essential to astrophotography is effective noise reduction, of both grainy “luminance” noise, as well as colorful speckles and splotches from “chrominance” noise. Programs should smooth noise without eliminating stars, removing star colors, or adding odd structures and artifacts.

Conversely, programs should offer a controllable level of sharpening, without introducing dark halos around stars, a sure sign of over-zealous sharpening.

Closeups of the tracked image comparing noise reduction and star image quality in all 9 programs. Tap or click to download a high-res version for closer inspection to see the pixel-level differences.

I tested noise reduction using the tracked version of my test images, as the pinpoint stars from the 45-megapixel Canon R5 will reveal any star elimination or discoloration.

Adobe Camera Raw’s aging noise reduction routine stood up very well against the new AI competitors. It smoothed noise acceptably, while retaining star colors and Milky Way structures. But turn it up too high, as might be needed for very high ISO shots, and it begins to blur or wipe out stars. AI noise reduction promises to solve this.

AI-Based Noise Reduction:

DxO PhotoLab’s Prime and DeepPrime AI-based options can also do a good job. But … I find DeepPrime (shown above) and the newer DeepPrimeXD (shown below) can introduce wormy looking artifacts to starfields. The older Prime method might be a better choice. However, the annoyance with DxO PhotoLab is that it is not possible to preview any of its Prime noise reduction results full-screen, only in a tiny preview window, making the best settings a bit of a guess, requiring exporting the image to see the actual results.

ON1 Photo RAW’s NoNoise AI can also do a good job, but has to be backed off a lot from the automatic settings its AI technology applies. Even so, I found it still left large-scale color blotches, a pixel-level mosaic pattern, and worst of all, dark halos around stars, despite me applying no sharpening at all to the image. ON1 continues to over-sharpen under the hood. I criticized it for star halos in my 2017 survey — the 2023 version behaves better, but still leaves stars looking ugly.

The other AI program, Luminar Neo with its Noiseless AI extension (an extra-cost option) did a poor job, adding strange artifacts to the background sky and colored halos around stars.

Comparing DxO’s three Prime noise reduction options on the untracked image. DeepPrimeXD is sharper!

Comparing DxO’s three Prime noise reduction methods on the tracked image. DeepPrimeXD is riddled with artifacts.

So beware of AI. As I show above with DxO, because they are not trained on starfields, AI routines can introduce unwanted effects and false structures. What works wonders on high-ISO wildlife or wedding shots can ruin astrophotos.

For a more complete test of AI programs, such as Topaz DeNoise AI and Noise XTerminator, made specifically for noise reduction, see my review from November 2022, Testing Noise Reduction Programs for Astrophotography.

Non AI-Based Noise Reduction:

Capture One smoothed noise very well, but tended to bloat stars and soften fine detail with its Single Pixel control turned up even to one pixel, as here.

Affinity Photo nicely smoothed noise, but also removed star colors, yet added colored rims to some stars, perhaps from poor de-Bayering. Serif Lab’s raw engine still has its flaws.

ACDSee Photo Studio also added loads of unacceptable halos to stars, and could not reduce noise well without smoothing details.

Darktable has very good noise reduction, including a panel specifically for Astrophoto Denoise. Great! Pity its routines seemed to wipe out star colors and fine structures in the Milky Way.

Exposure X7 smoothed noise well, but also wiped out details and structures, and its sharpening adds dark halos to stars.

That said, it might be possible to eke out better results from all these programs with more careful settings. Backing off sharpening or noise reduction can avoid some of the unwanted side effects I saw, but leave more noise.

Adobe Camera Raw does eliminate most random hot or dead pixels “under the hood.” However, I wish it had an adjustable filter for removing any that still remain (usually from thermal noise) and that can plague the shadows of nightscapes. Single-pixel filters are offered by Capture One, Darktable, DxO, and Exposure X7. Though turning them up too high can ruin image detail.

WINNERS: Adobe and DxO PhotoLab (if the latter is used cautiously)

LOSERS: ACDSee, Affinity, Darktable, Exposure X7, and Luminar Neo for unacceptable loss of detail and star colors, while adding in false structures (Neo)

Feature-by-Feature Details — 4. Shadow Recovery

While all programs have exposure and contrast adjustments, the key to making a Milky Way nightscape look good is being able to boost the shadows in the dark starlit ground, while preventing the sky or other areas of the image from becoming overly bright or washed out.

Comparing Shadow Recovery in two programs (Camera Raw – top – and DxO PhotoLab – middle) that worked quite well, with Darktable (bottom) that did not.

In the three examples above I have applied only white balance and exposure correction, then “lifted” the Shadows. I added some contrast adjustment to Darktable, to help improve it, and Smart Lighting to the DxO image, which was needed here.

Here are my findings, roughly in order of decreasing image quality, but with Adobe first as the one to match or beat.

Adobe Camera Raw has a very good Shadows slider that truly affects just the dark tonal areas and with a slight touch (turning it up to 100 doesn’t wipe out the image). Some other programs’ Shadows adjustments are too aggressive, affect too wide a range of tones, or just add a grey wash over the image, requiring further tweaks to restore contrast.

Capture One did an excellent job on Shadow recovery under its High Dynamic Range set of sliders. The dark landscape brightened without becoming flat or grey. This is a primary contributor to its excellent image quality.

DxO PhotoLab’s Shadows slider affects a wider tonal range than ACR or Capture One, also brightening mid-tones, though it has a Midtones slider to separately adjust those. On its own, the Shadows slider didn’t work as well as in ACR or Capture One. But DxO’s superb feature is its “Smart Lighting,” which can work wonders on a scene with one click. Another unique adjustment is “ClearView Plus,” a form of Dehaze which can snap up contrast, often too aggressively, but it can be backed off in intensity. Those two adjustments alone might be reason enough to use PhotoLab.

ON1 Photo RAW’s Shadows slider affected too wide a range of tonal values, brightening the entire scene and making it look flat. This can be overcome with some tweaks to the Contrast, Blacks and Midtones sliders. It takes more work to make a scene look good.

ACDSee’s Fill Light and Shadows sliders were also much too broad. But its unique LightEQ panel has options for “Standard” and “Advanced” settings which each provide an equalizer interface for making more selective tonal adjustments. It worked well, though the image looked too harsh and contrasty, despite me adding no contrast adjustments, the opposite flaw of other programs.

Luminar Neo’s Shadows slider under its DevelopRAW panel was also broad, washing out contrast, requiring a liberal application of its SuperContrast slider to return the image to a better look. But the final result looked fine.

Exposure X7’s Shadows slider also lowered overall contrast, requiring boosting Contrast and Blacks to return the image to a pleasing tonal balance.

Affinity Photo’s Shadows slider did a far better job in its new v2 (released in late 2022) than in the original Affinity Photo, which was frankly awful. Even so, I found Affinity Photo 2 still tended to produce flat results, hard to compensate for from within the Develop Persona, as its options are so limited.

Darktable’s Shadows slider (which has several sub-sliders) produced a flat result. Despite the numerous variations of other contrast and level adjustments scattered over various panels, I could not get a pleasing result. It will take a true Darktable fan and expert to exact a good image from its bewildering options, if it’s even possible.

WINNERS: Capture One and DxO PhotoLab, plus Adobe still works well

LOSERS: Affinity Photo and Darktable

Feature-by-Feature Details — 5. Local Adjustments and Masking

This is the area where programs have made major improvements in the five years since my last survey of raw developers. Thus I devote a major section to the feature.

With accurate and easy masking it is now easier to apply adjustments to just selected areas of a raw image. We can finish off a raw file to perhaps be publication ready, without having to use a layer-based program like Photoshop to perform those same types of local adjustments. Adobe Camera RAW, Luminar Neo, and ON1 Photo Raw are leaders in this type of advanced AI masking. But other programs have good non-AI methods of masking – and making – local adjustments.

Adobe Camera Raw (and Adobe Lightroom) now has far better masking than in older versions that used the awkward method of applying multiple “pins.” Masks now occupy separate layers, and AI masks can be created in one-click for the sky (and ground by inverting the Sky mask) and for key subjects in the image. Other non-AI masks can be created with brushes (with an Auto Mask option for edge detection) and gradient overlays, and with the option of luminance and color range masks. The AI-created Sky masks proved the most accurate compared to other programs’ AI selections, though they can intrude into the ground at times. But the sky masks do include the stars. In all, Camera Raw (or Lightroom) has the most powerful masking tools of the group, though they can be tricky to master.

ACDSee Photo Studio allows up to eight different brushed-on mask areas, each with its own adjustments, in addition to gradient masks. There is no edge detection as such, though the brushes can be limited to selecting areas of similar brightness and color. The “Magic” brush option didn’t help in selecting just the sky and stars. Local adjustments are possible to only Exposure, Saturation, Fill Light, Contrast, and Clarity. So no local color adjustments are possible. In all, local adjustments are limited.

Affinity Photo has, in its Develop Persona, what it calls Overlays, where for each Overlay, or layer, you can brush on separate sets of adjustments using all the sliders in the Develop Persona. Oddly, there is no option for decreasing the opacity of a brush, only its size and feathering. While there is an Edge Aware option, it did a poor job on the test image detecting the boundary between land and sky, despite the edge being sharply defined. So local adjustments require a lot of manual brushing and erasing to get an accurate mask. The red mask Overlay, useful at times, has to be turned on and off manually. Other programs (ACR and Capture One) have the option of the colored overlay appearing automatically just when you are brushing.

Capture One offers adjustment layers for each mask required. The only “smart” brush is the Magic Brush which affects areas across the entire image with similar luminosity. There isn’t any edge detection option as such, so creating masks for the sky and ground is still largely a manual process requiring careful brushing. Separate layers can be added for healing and retouching. While Capture One’s local adjustments can work well, they require a lot more manual work than do programs equipped with AI-driven selection tools.

DxO PhotoLab allows multiple local adjustments, with the option of an Auto Mask brush that nicely detects edges, though the mask overlay itself (as shown above on the sky) doesn’t accurately show the area being affected. Strange. Masks can also be added with what are called Control Points to affect just areas of similar luminance within a wide circle, often requiring multiple Control Points to create an adjustment across a large region. Masks can also be created with adjustable brushes. Each masked area is then adjusted using a set of equalizer-like mini-controls, rather than in the main panels. In all, it’s a quirky interface, but it can work quite well once you get used to it.

Exposure X7 offers adjustment layers with options to add a gradient, or to draw or brush on an area to make a selection. There is no edge detection, only a color range mask option, so creating a sky or ground mask can require lots of hand painting. I found the preview sluggish, making it a bit of a trial-and-error exercise to make fine adjustments. However, the full range of tone and color adjustments can be applied to any local mask, a plus compared to ACDSee for example.

Luminar was first out with AI masks to automatically select the sky, and various landscape elements it detects. In all it does a good job, making it easy to add local adjustments. There are also gradient tools and normal brushes, but oddly, considering the amount of AI Luminar relies on, there is no edge detection (at least, as of early 2023). So brushing to create a mask requires a lot of finicky painting and erasing to refine the mask edge. The strong point is that masks can be added to any of Luminar’s many filters and adjustment panels, allowing for lots of options for tweaking the appearance of selected areas, such as adding special effects like glows to the sky or landscape. However, most of those filters and effects are added to the image after it is developed, and not to the original raw file.

ON1’s AI Sky mask does not include the stars.

ON1 Photo RAW has always offered good local adjustments, with each occupying its own layer. Photo RAW 2023 added its new “Super Select” AI tools to compete with Adobe. But they are problematic. The select Sky AI masking fails to include stars, leaving a sky mask filled with black holes, requiring lots of hand painting to eliminate. You might as well have created the mask by hand to begin with. Plus in the test image, selecting “Mountain” to create a ground mask just locked up the program, requiring a Force Quit to exit it. However, ON1’s conventional masks and adjustments work well, with a wide choice of brush options. The Perfect Brush detects areas of similar color, not edges per se.

WINNERS: Adobe and Luminar for accurate AI masks

LOSER: Darktable— it has no Local Adjustments at all

Feature-by-Feature Details — 6. Overall Finished Image Quality

I provide each of the finished images for the untracked star trail example below, under Program-by-Program Results. But here’s a summary, in what I admit is a subjective call. One program would excel in one area, but be deficient in another. But who produced the best looking end result?

Overall, I think Capture One came closest to matching or exceeding Adobe Camera Raw for image quality. Its main drawback is the difficulty in creating precise local adjustment masks.

DxO PhotoLab also produced a fine result, but still looking a little flat compared to ACR and Capture One. But it does have good AI noise reduction.

In the middle of the ranking are the group of ACDSee Photo Studio, Exposure X7, and ON1 Photo RAW. Their results look acceptable, but closer examination reveals the flaws such as haloed stars and loss of fine detail. So they rank from Fair to Good, depending on how much you pixel peep!

Luminar Neo did a good job, though achieving those results required going beyond what its DevelopRAW panel can do, to apply Neo’s other filters and effects. So in Neo’s case, I did more to the image than what was possible with just raw edits. But with Luminar, the distinction between raw developer and layer-based editor is fuzzy indeed. It operates quite differently than other programs tested here, perhaps refreshingly so.

For example, with the more conventionally structured workflow of Affinity Photo, I could have exacted better results from it had I taken the developed raw image into its Photo Persona to apply more adjustments farther down the workflow. The same might be said of ON1 Photo RAW.

But the point of this review was to test how well programs could do just at the raw-image stage. Due to the unique way it operates, I’ll admit Luminar Neo did get the advantage in this raw developer test. Though it failed on several key points.

WINNERS: Adobe and Capture One, with DxO a respectable second

LOSER: Darktable— it was just plain poor

Feature-by-Feature Details — 7. Copy & Paste Settings

Getting one image looking great is just the first step. Even when shooting nightscape stills we often take several images to stack later.

As such, we want to be able to process just one image, then copy and paste its settings to all the others in one fell swoop. And then we need to be able to inspect those images in thumbnails to be sure they all look good, as some might need individual tweaking.

While it’s a useful feature for images destined for a still-image composite, Copy & Paste Settings is an absolutely essential feature for processing a set for a time-lapse movie or a star trail stack.

The Copy and Paste Settings panels from the 8 programs that offer this feature.

I tested the programs on the set of 360 time-lapse frames of the Perseid meteor shower used next for the Batch Export test.

Adobe Bridge makes it easy to copy and paste Camera Raw settings to identically process all the files in a folder. Lightroom has a similar function. Adobe also has adaptive masks, where a sky mask created for one image will adapt to all others, even if the framing or composition changes, as it would in a motion-control time-lapse sequence or panorama set. Applying settings to several hundred images is fairly quick, though Bridge can be slow at rendering the resulting thumbnails.

ON1 Photo RAW can also copy and paste AI masks adaptively, so a Sky mask created for one image will adapt to match another image, even if the framing is different. However, applying all the settings to a large number of images and rendering the new previews proved achingly slow. And it’s a pity it doesn’t create a better sky mask to begin with.

Capture One has a single Copy and Apply Adjustments command where you develop one image, select it plus all the other undeveloped images in the set to sync settings from the processed image to all the others. But the adjustment layers and their masks copy identically; there is no adaptive masking because there are no AI-generated masks. However, applying new settings to hundreds of images and rendering their thumbnails is very fast, better than other programs.

DxO PhotoLab’s Control Point masks and local adjustments also copy identically. Copying adjustments from one image to the rest in the set of 360 test images was also very fast.

ACDSee Photo Studio and Exposure X7 also allow copying and pasting all or selected settings, including local adjustment masks. ACDSee was slow, but Exposure X7 was quite quick to apply settings to a large batch of images, such as the 360 test images.

Darktable’s function is under the History Stack panel where you can copy and paste all or selected settings, but all are global — there are no local adjustments or masks.

Luminar Neo allows only copying and pasting of all settings, not a selected set. When testing it on the set of 360 time-lapse frames, Neo proved unworkably slow, taking as much as an hour to apply settings and render the resulting thumbnails in its Catalog view, during which time my M1 MacBook Pro warned the application was running out of memory, taking up 110 Gb! I had to Force Quit it.

Affinity Photo is capable of editing only one image at a time. There is no easy or obvious way to copy the Develop Persona settings from one raw image, open another, then paste in those settings. You can only save Presets for each Develop Persona panel, making transferring settings from one image to even just one other image a tedious process.

Affinity Photo with several raw images stacked and identically processed with the method below.

Affinity Workaround

But … there is a non-obvious and unintuitive method in Affinity which works for stacking and processing a few raw files for a blend:

Process one raw image and then click Develop so it moves into the Photo Persona, as a “RAW Layer (Embedded),” a new feature in Affinity Photo 2.
Find the other raw image files (they won’t have any settings applied) and simply drag them onto the Photo Persona screen.
Use the Move tool to align the resulting new layers with the original image.
Select all the image layers (but only the first will have any settings applied) and hit the Develop Persona button.
Then hit the Develop button — this will apply the settings from the first image to all the others in the layer stack. It’s the best Affinity can do for a “copy and paste” function.
Change the blend mode or add masks to each layer to create a composite or star trail stack.
Each layer can be re-opened in the Develop Persona if needed to adjust its settings.
It’s all a bit of a kludge, but it does work.

WINNERS: Capture One for blazing speed; Adobe and ON1 for adaptive masks

LOSER: Affinity Photo, for lacking this feature entirely, except for a method that is not at all obvious and limited in its use.

Feature-by-Feature Details — 8. Batch Export

Once you develop a folder of raw images with “Copy & Paste,” you now have to export them with all those settings “baked into” the exported files.

This step creates an intermediate set of TIFFs or JPGs to either assemble into a movie with programs such as TimeLapse DeFlicker, or to stack into a star trail composite using software such as StarStaX.

The Batch Export panels from all 9 programs.

To test the Batch Export function, I used each program to export the same set of 360 developed raw files taken with a 20-megapixel Canon R6, shot for a meteor shower time-lapse, exporting them into full-resolution, low-compression JPGs.

While all programs can do the task, some are much better than others.

Adobe Bridge has a configurable Export panel (though it can be buggy at times), as does Lightroom. Its speed is good, but is beaten by several of the competitors.

Even Affinity Photo can do a batch export, done through its “New Batch Job” function. As with its other image selection operations, Affinity depends on your operating system’s Open dialog box to pick images. Exporting worked well, though without being able to develop a batch of raw files, I’m not sure why you would have cause to use this batch function to export them. I had to test it with undeveloped raws. Oddly, Affinity’s exported JPGs (at 5496 x 3664 pixels) were slightly larger than the size of the original raws (which were 5472 x 3648 pixels). No other program did this.

Most programs allow saving combinations of Export settings as frequently used presets. An exception is Exposure X7 where separate presets have to be saved and loaded for each option in its Export panel, awkward. And Luminar Neo’s batch export is basic, with no option for saving Export presets at all.

In the export of the 360 test images, each program took:

Adobe Bridge 15 minutes (after 3 attempts to get it to actually work!)
ACDSee Photo Studio 33 minutes
Affinity Photo 2 32 minutes
Capture One 23 6 minutes
Darktable 4 16 minutes
DxO PhotoLab 6 8 minutes
Exposure X7 5 minutes 30 seconds
Luminar Neo 8.5 hours (!)
ON1 Photo RAW 2023 1.4 hours

This was on my M1 Max MacBook Pro. Your mileage will vary! The clear winners in the export race were Exposure X7, Capture One, and DxO. ON1 was way behind the pack. Luminar was impossibly slow. It is not a program for working with lots of images.

ON1’s Time-Lapse Function

Unique among these programs, ON1 Photo RAW provides a Time-Lapse function that allows directly exporting developed raw files to a final movie, without the need to export an intermediate JPG set. That sounds like a great time saver. Only Adobe After Effects can do the same.

However … ON1’s options are limited: up to a maximum DCI 4K size, in H264 or Apple ProRes codecs, and with a choice of just three frame rates: 24, 25, or 30 frames per second. A dedicated assembly program such as TimeLapse DeFlicker can do a much better job, and faster, with more options such as frame blending, and up to 8K movie sizes.

And oddly, ON1’s Time-Lapse panel provides no option for where to save the movie or what to name it — it defaults to saving the movie to the original folder with the images, and with the name of one of the images. I had to search for it to locate it.

WINNERS: Exposure X7 and Capture One for sheer speed

LOSER: Luminar Neo for being unusably slow

Feature-by-Feature Details — 9. Advanced Features

Here I’ve noted what programs offer what features, but I tested only the panorama stitching function. For a panorama test I used a set of seven images shot with the Canon R5 and RF15-35mm lens at Peyto Lake, Banff.

The Panorama options from 4 programs. ON1 (lower left) failed to stitch 2 of the 7 segments).

Adobe Camera Raw (and Lightroom) offers HDR Merge and Panorama stitching plus, uniquely, the ability to merge multi-exposure HDR panoramas. But it has no Focus Stack option (that’s in Photoshop). For panoramas, ACR offers a choice of projection geometries, and the very excellent Boundary Warp function for filling in blank areas, as well as content-aware Fill Edges. The result is a raw DNG file.

Capture One has HDR Merge and Panorama stitching, but no Focus Stack option. Like ACR, Capture One’s panorama mode offers a choice of projection geometries and results in a raw DNG file for further editing at the raw level. It worked well on the test set, though lacks anything equivalent to ACR’s content-aware Fill Edges and Boundary Warp options.

ON1 Photo RAW offers HDR Merge, Focus Stack, and Panorama stitching of raw files. Using the same seven images that ACR and Capture One succeeded with, ON1 failed to stitch two of the segments, leaving a partial pano. It does offer a limited choice of projection methods and, like ACR, has the option to warp the image to fill blank areas. It creates a raw DNG file.

Affinity Photo also offers HDR Merge, Focus Stack, and Panorama stitching, all from raw files. However, the panorama function is quite basic, with no options for projection geometry or content-aware fill. But it did a good job blending all segments of the test set seamlessly. The result is a raw file that can be further processed in the Develop Persona.

ACDSee Photo Studio for Mac lacks any HDR, Focus Stack, or Panorama stitching. Those functions are available in the Windows versions (Pro and Ultimate), but I did not test them.

Luminar Neo offers HDR Merge and Focus Stack through two extra-cost extensions. As of this writing it does not offer Panorama stitching, but more extensions (yet to be identified!) will be released in 2023.

Darktable offers just HDR Merge, but no Focus Stack or Panorama functions.

DxO PhotoLab 6 lacks any HDR, Focus Stack or Panorama functions. Ditto for Exposure X7. Those are serious deficiencies, as we have a need for all those functions when processing nightscapes. You would have to develop the raw files in DxO or Exposure, then export TIFFs to merge or stitch them using another program such as Affinity Photo.

WINNERS: Adobe and Capture One

LOSER: DxO for missing key functions expected in a premium “Adobe killer”

Program-by-Program Summary

I could end the review here, but I feel it’s important to present the evidence, in the form of the final images, as best I could process them with each of the programs. I rate their overall image quality and performance on a subjective scale of Poor / Fair / Good / Excellent, with additional remarks about the Pros and Cons of each program, as I see them.

Adobe Camera Raw (also applies to Adobe Lightroom)

IMAGE QUALITY: Excellent

PROS: ACR has excellent selective shadow recovery and good noise reduction which, while not up to the level of new AI methods, doesn’t introduce any weird AI artifacts. Its panels and sliders are fairly easy to use, with a clean user interface. Its new AI masking and local adjustments are superb, though take some practice to master.

CONS: It is available only by monthly or annual subscription, and lacks the more advanced AI noise reduction, sharpening, and one-click special effects of some competitors. Using the Adobe suite requires moving between different Adobe programs to perform all functions. Adobe Bridge, a central program in my workflow, tends to be neglected by Adobe, and suffers from bugs and deficiencies that go uncorrected.

ACDSee Photo Studio (for Mac)

IMAGE QUALITY: Fair

PROS: Photo Studio in its various versions offers good image management functions, making it suitable as a non-subscription Lightroom alternative. It offers an advanced array of tonal and color adjustments in an easy-to-use interface.

CONS: It produced badly haloed stars and had poor noise reduction. Its local adjustments are limited and lag behind the competition with no AI functions. It has no panorama stitching or HDR merging functions in the Mac version — the Windows versions get much more love and attention from ACDSee.

Affinity Photo 2

IMAGE QUALITY: Fair (for its Develop Persona) / Good to Excellent (as a Photoshop replacement)

PROS: Affinity Photo is certainly the best alternative to Photoshop for anyone looking to avoid Adobe. It is an excellent layer-based program (far better than GIMP) with unique features for astrophotographers such as stacking and gradient removal. With v2, it is now possible to transfer a raw file from the Develop Persona to the Photo Persona non-destructively, allowing re-opening the raw file for re-editing, similar to Adobe’s Camera Raw Smart Objects.

CONS: Affinity Photo’s Develop Persona for raw files is basic, with limited adjustments and producing average results at best. Transferring settings from one raw file to others is difficult, if not impossible. Affinity Photo is designed for editing single images only.

Capture One 23

IMAGE QUALITY: Excellent

PROS: Capture One has excellent shadow recovery and color adjustment controls. Local adjustments are easy to add and edit, though lack edge detection and AI selection. It has excellent cataloging functions, and overall superb image quality. It’s a good Lightroom alternative.

CONS: It’s costly to purchase, and more expensive than Adobe’s Creative Cloud to subscribe to. It can easily soften stars if not careful. It lacks AI masking, and overall the program tends to lag behind competitors by a few years for advanced features — Capture One added panorama stitching only a couple of versions back. I found the program also tended to litter my drive with Capture One folders.

Darktable

IMAGE QUALITY: Poor

PROS: It’s free! And it offers many adjustments and intricate options not found elsewhere that the technically minded will enjoy experimenting with.

CONS: Darktable’s community of developers has added a bewildering array of panels in a confusing interface, making Darktable not for beginners nor the feint of heart. I struggled with it, all for poor results. Just finding the Export function was a challenge. Darktable is a program designed by programmers for use by other programmers who love to play with image data, and who care little for a user interface friendly to “the rest of us!”

DxO PhotoLab 6

IMAGE QUALITY: Excellent

PROS: Along with Capture One, I found DxO PhotoLab capable of producing a good-looking image, the equal of or perhaps better than Camera Raw, partly because of DxO’s ClearView and Smart Lighting options. It has lots of downloadable camera and lens modules for automatic lens corrections. Its noise reduction was excellent, though its DeepPrime and DeepPrimeXD options can add AI artifacts.

CONS: There are no adjustment layers or masks as such. Local adjustments are done through DxO’s quirky Control Point interface which isn’t as visually intuitive nor as precise as masks and layers. As of PhotoLab 6, DxO has yet to offer panorama or HDR merging, lagging far behind the competition.

Exposure X7

IMAGE QUALITY: Fair

PROS: Exposure has a full set of tonal and color adjustments, and essential image management functions. It has good local adjustment layers, though with no AI or smart brushes to automatically detect edges. It produced acceptable final results, though still looking a little flat.

CONS: Exposure lacks any panorama stitching or HDR merging functions. Its noise reduction can wipe out stars and image details, and its sharpening adds dark halos to stars. It often crashed during my testing, by simply quitting unexpectedly. Annoying.

Luminar Neo

IMAGE QUALITY: Good to Excellent

PROS: Luminar has a clean, fresh interface with many powerful AI-driven functions and effects unique to Luminar and that are easy to apply. The final result looks fine. Its AI masks work quite well. Neo also works as a plug-in for Photoshop or Lightroom.

CONS: Luminar is expensive to purchase outright with all the Extensions, with a subscription the most economical method of acquiring, and maintaining, the full package. Its Noiseless AI didn’t handle starfields well. Neo lacks a useable cataloging function, and the version tested had numerous serious bugs. It is best for editing just single images.

ON1 Photo RAW 2023

IMAGE QUALITY: Good

PROS: ON1 Photo RAW is the only program of the set that can: catalog images, develop raw files, and then layer and stack images, performing all that Lightroom and Photoshop can do. It can serve as a one-program solution, and has excellent Effects and NoNoise AI, also available as plug-ins for Adobe software. It offers layer-based editing as well.

CONS: ON1 consistently produces dark halos around stars from over-sharpening in its raw engine. These cannot be eliminated. Its AI selection routines are flawed. Its AI noise reduction can leave artifacts if applied too aggressively, which is the default setting. Opening images from the Browse module as layers in the Edit module can be slow. It offers no stack modes (present in Photoshop and Affinity) for easy noise smoothing or star trail stacking, and the alternative — changing layer Blend modes — has to be done one at a time for each layer, a tedious process for a large image stack.

Why Didn’t I Test …?

… [Insert your favorite program here!] No doubt it’s one you consider badly neglected by all the world’s photographers!

But … as I stated at the outset, I tested only programs offered for both MacOS and Windows. I tested the MacOS versions — and for nightscapes, which are more demanding than normal daytime scenes.

Icons for the programs not tested. How many can you identify? Hint: They are in alphabetical order.

I did not test:

Adobe Photoshop Elements —Effectively Photoshop “Lite,” Elements is available for $99 as a one-time purchase with a perpetual license, for both MacOS and Windows. Optional annual updates cost about $80. While it offers image and adjustment layers, and can open .PSD files, Elements cannot do much with 16-bit images, and has limited functions for developing raw files, in its version of Camera Raw “Lite.” And its Lightroom-like Organizer module does not not have any Copy & Paste Settings or batch export functions, making it unsuitable for batch editing or time-lapse production.

Like Apple’s Photos and other free photo apps, I don’t consider Elements to be a serious option for nightscape and time-lapse work. A Creative Cloud Photo subscription doesn’t cost much more per year, yet gets you far, far more in Adobe’s professional-level software.

Corel PaintShop — As with ACDSee’s product suite, Corel’s PaintShop is available in Pro and Pro Ultimate versions, both updated for 2023, and each with extensive raw and layer-based editing features. But they are only for Windows. If you are a PC user, PaintShop is certainly worth testing out. Their neglected MacOS program (also available for Windows and Linux) is the raw developer AfterShot Pro 3 (currently at v3.7.0.446). It is labeled as being from 2017, and last received a minor bug fix update in January 2021. I included it in my 2017 survey, but could not this year as it refused to recognize the CR3 raw files from my Canon R5 and R6 cameras.

Darkroom and Acorn are two Mac-only apps wth just basic features. There are no doubt numerous other similar Windows-only apps that I am not familiar with.

GIMP — Being free, it has its loyal fans. But it is not a raw developer, so it is not tested here. It is favorite of some astrophotographers as a no-cost substitute for Adobe Photoshop or Affinity Photo. It’s available for MacOS and Windows.

Iridient Developer — Its anachronistic, text-only website looks like it comes from 1995, giving the impression that this raw developer should be free, open-source software. It isn’t; it costs $99. It is a basic raw developer but only for MacOS. It is updated frequently, and a trial copy is available.

Pixelmator Pro — While it is a very capable and well-supported program with some excellent features, it too is available only for MacOS. Like Affinity Photo, it seems to be primarily for editing individual raw images, and lacks any image management functions, notably Copy & Paste Settings.

PixInsight — This specialized astrophoto program is designed for deep-sky image processing and bringing out the most subtle structures in faint nebulas and galaxies. For those it works wonders. But it is not suitable for nightscapes. Examples I’ve seen from PI fans who have used it for nightscapes, including images I’ve sent them for their expert processing, have not impressed me.

RawTherapee — As of early January 2023 when I completed my testing, the latest version of this free open-source program, v5.9, was available only for Windows and Linux. The MacOS version was still back at v5.8 from February 2020, a version that was unable to open the Canon CR3 raw files I was using in my tests. While the CR3 format has been out for several years, RawTherapee was still not supporting it, a hazard of open-source software dependent on the priorities of volunteer programmers who mostly use Windows. Like Darktable, RawTherapee is an incredibly complex program to use, with programmers adding every possible panel, slider and checkbox they could think of. [UPDATE MARCH 2023: RawTherapee 5.9 for MacOS is now available and opens Canon .CR3 files. Mac users might certainly want to try it. And Windows users, too!]

Topaz Studio — While Topaz Labs has been busy introducing some fine AI specialty programs, such as DeNoise AI, their main photo editor, Topaz Studio, has been neglected for years and, as of late 2022, was not even listed as a product for sale. It’s gone.

What About? — To prevent the number of programs tested from growing even larger, I did not include a few other little-known and seldom-used programs such as Cyberlink PhotoDirector and Picktorial, though I’m sure they have their fans.

I also did not test any camera manufacturer programs, such as Canon’s Digital Photo Professional, Nikon’s CaptureNX, or Sony’s ImagingEdge. They will open raw images only from their own cameras. Few photographers use them unless forced to, perhaps to open new raw files not yet supported by Adobe, DxO, et al, or to access files created by special camera functions such as Pixel Shift or Raw Burst Mode.

Recommendations

Having used Adobe software for decades, I’m used to its workings and the look it provides images. I’ve yet to see any of the competitors produce results so much better that they warrant me switching programs. At best, the competitors produce results as good as Adobe, at least for nightscape astrophotos, though with some offering unique and attractive features.

For example, the AI noise reduction routines in DxO PhotoLab and ON1 Photo RAW can outperform Adobe Camera Raw and Lightroom. Adobe needs to update its raw editing software with more advanced noise reduction and sharpening. Even so, the AI routines in the competitors are prone to creating odd artifacts, so have to be applied carefully to astrophotos.

A possible workflow: DxO PhotoLab or Capture One into Affinity Photo

As I recommended in 2017, for those who refuse to use Adobe — or any software by subscription — a possible combination for the best astrophoto image quality might be DxO PhotoLab 6 for raw developing and basic time-lapse processing, paired with Affinity Photo 2 for stacking and compositing still images, from finished TIFF files exported out of DxO then opened and layered with Affinity.

An example of images developed in Capture One and then layered and masked in Affinity Photo.

The pairing of Capture One with Affinity could work just as well, though is more costly. And anyone who hates software by subscription in principle might want to avoid Capture One as they are pushing customers toward buying only by subscription, as is ON1.

For a single-program solution, I’d recommend ON1 Photo RAW more highly, if only it produced better star image quality. Its raw engine continues to over-sharpen, and its AI masking functions are flawed, though will likely improve. I routinely use ON1’s Effects plug-in from Photoshop, as it has some excellent “finishing-touch” filters such as Dynamic Contrast. I find ON1’s NoNoise AI plug-in also very useful.

The same applies to Luminar Neo. While I can’t see using it as a principle processing program, it works very well as a Photoshop plug-in for adding special effects, some with its powerful and innovative AI routines.

Finally — Download Trials and Test!

But don’t take my word for all of this. Please test for yourself!

With the exception of Luminar Neo, all the programs I tested (and others I didn’t, but you might be interested in) are available as free trial copies. Try them out on your images and workflow. You might find you like one program much better than any of the others or what you are using now.

Often, having more than one program is useful, if only for use as a plug-in from within Lightroom or Photoshop. Some plug-ins made for Photoshop also work from within Affinity Photo, though it is hit-and-miss what plug-ins will actually work. (In my testing, plug-ins from DxO/Nik Collection, Exposure X7, ON1, RC-Astro, and Topaz all work; ones from Skylum/Luminar install but fail to run.)

LRTimelapse working on the meteor shower time-lapse frames.

While I was impressed with Capture One and DxO PhotoLab, for me the need to use the program LRTimelapse (shown above) for processing about 80 percent of all the time-lapse sequences I shoot means the question is settled. LRTimelapse works only with Adobe software, and the combination works great and improves wth every update of LRTimelapse.

Even for still images, the ease of working within Adobe’s ecosystem to sort, develop, layer, stack, and catalog images makes me reluctant to migrate to a mix of programs from different companies, especially when the cost of upgrading many of those programs is not much less than, or even more costly, than an Adobe Photo plan subscription.

However … if it’s just a good raw developer you are after for astro work, without paying for a subscription, try Capture One 2023 or DxO PhotoLab 6. Try Affinity Photo if you want a good Photoshop replacement.

Clear skies! And thanks for reading this!

November 15, 2022April 27, 2023

Testing Noise Reduction Programs for Astrophotography

In a detailed technical blog I compare six AI-based noise reduction programs for the demands of astrophotography. Some can work wonders. Others can ruin your image.

Over the last two years we have seen a spate of specialized programs introduced for removing digital noise from photos. The new generation of programs use artificial intelligence (AI), aka machine learning, trained on thousands of images to better distinguish unwanted noise from desirable image content.

At least that’s the promise – and for noisy but normal daytime images they do work very well.

But in astrophotography our main subjects – stars – can look a lot like specks of pixel-level noise. How well can each program reduce noise without eliminating stars or wanted details, or introducing odd artifacts, making images worse.

To find out, I tested six of the new AI-based programs on real-world – or rather “real-sky” – astrophotos. Does one program stand out from the rest for astrophotography?

NOTE: All the images are full-resolution JPGs you can tap or click on to download for detailed inspection. But that does make the blog page slow to load initially. Patience!

TL;DR SUMMARY

The new AI-trained noise reduction programs can indeed eliminate noise better than older non-AI programs, while leaving fine details untouched or even sharpening them.

Of the group tested, the winner for use on just star-filled images is a specialized program for astrophotography, NoiseXTerminator from RC-Astro.

For nightscapes and other images, Topaz DeNoise AI performed well, better than it did in earlier versions that left lots of patchy artifacts, something AI programs can be prone to.

While ON1’s new NoNoise AI 2023 performed fine, it proved slightly worse in some cases than its earlier 2022 version. Its new sharpening routine needs work.

Other new programs, notably Topaz Photo AI and Luminar’s Noiseless AI, also need improvement before they are ready to be used for the rigours of astrophotography.

For reasons explained below, I would not recommend DxO’s PureRAW². [See below for comments on the newer DxO PureRaw³, which suffers from the same issues.]

The three test images in Adobe Camera Raw showing the Basic settings applied.

METHODOLOGY

As described below, while some of the programs can be used as stand-alone applications, I tested them all as plug-ins for Photoshop, applying each as a smart filter applied to a developed raw file brought into Photoshop as a Camera Raw smart object.

Most of these programs state that better results might be obtainable by using the stand-alone app on original raw files. But for my personal workflow I prefer to develop the raw files with Adobe Camera Raw, then open those into Photoshop for stacking and layering, applying any further noise reduction or sharpening as non-destructive smart filters.

Many astrophotographers also choose to stack unedited original images with specialized stacking software, then apply further noise reduction and editing later in the workflow. So my workflow and test procedures reflect that.

However, the exception is DxO’s PureRAW². It can work only on raw files as a stand-alone app, or as a plug-in from Adobe Lightroom. It does not work as a Photoshop plug-in. I tested PureRAW² by dropping raw Canon .CR3 files onto the app, then exporting the results as raw DNG files, but with the same settings applied as with the other raw files. For the nightscape and wide-field images taken with lenses in DxO’s extensive database, I used PureRAW’s lens corrections, not Adobe’s.

As shown above, I chose three representative images:

A nightscape with star trails and a detailed foreground, at ISO 1600.
A wide-field deep-sky image at ISO 1600 with an 85mm lens, with very tiny stars.
A close-up deep-sky image taken with a telescope and at a high ISO of 3200, showing thermal noise hot pixels.

Each is a single image, not a stack of multiple images.

Before applying the noise reduction, the raw files received just basic color corrections and a contrast boost to emphasize noise all the more.

THE CONTENDERS

In the test results for the three images, I show the original raw image, plus a version with noise reduction and sharpening applied using Adobe Camera Raw’s own sliders, with luminance noise at 40, color noise at 25, and sharpening at 25.

I use this as a base comparison, as it has been the noise reduction I have long applied to images. However, ACR’s routine (also found in Adobe Lightroom) has not changed in years. It is good, but it is not AI.

[See below for an April 2023 update with a comparison of Adobe’s new AI Denoise with DxO DeepPrimeXD and Topaz PhotoAI.]

The new smart AI programs should improve upon this. But do they?

PLEASE NOTE:

I have refrained from providing prices and explaining buying options, as frankly some can be complex!
For those details and for trial copies, go to the software’s website by clicking on the link in the header product names below.
All programs are available for Windows and MacOS. I tested the latter versions.
I have not provided tutorials on how to use the software; I have just reported on their results. For trouble-shooting their use, please consult the software company in question.

ON1 NoNoise AI 2023

ON1’s main product is the Lightroom/Photoshop alternative program called ON1 Photo RAW, which is updated annually to major new versions. It has full cataloging options like Lightroom and image layering like Photoshop. Its Edit module contains the NoNoise AI routine. But NoNoise AI can be purchased as a stand-alone app that also installs as a plug-in for Lightroom and Photoshop. It’s what I tested here. The latest 2023 version of NoNoise AI added ON1’s new Tack Sharp AI sharpening routine.

Version tested: 17.0.1

Topaz DeNoise AI

This program has proven very popular and has been adopted by many photographers – and astrophotographers – as an essential part of an editing workflow. It performs noise reduction only, offering a choice of five AI models. Auto modes can choose the models and settings for you based on the image content, but you can override those by adjusting the strength, sharpness, and recovery of original detail as desired.

A separate program, Topaz Sharpen AI, is specifically for image sharpening, but I did not test it here. Topaz Gigapixel AI is for image resizing.

Version tested: 3.7.0

Topaz Photo AI

In 2022 Topaz introduced this new program which incorporates the trio of noise reduction, sharpening and image resizing in one package. Like DeNoise, Sharpen and Gigapixel, Photo AI works as a stand-alone app or as a plug-in for Lightroom and Photoshop. Photo AI’s Autopilot automatically detects and applies what it thinks the image needs. While it is possible to adjust settings, Photo AI offers much less control than DeNoise AI and Topaz’s other single-purpose programs.

As of this writing in November 2022 Photo AI is enjoying almost weekly updates, and seems to be where Topaz is focusing its development and marketing effort. [See below for a test of PhotoAI v1.3.1, current as of April 2023.]

Version tested: 1.0.9

Luminar Neo’s Edit interface with choices of many filters and effects, including Noiseless AI.

Luminar Neo Noiseless AI

Unlike the other noise reduction programs tested here, Luminar Neo from the software company Skylum is a full-featured image editing program, with an emphasis on one-click AI effects. One of those is the new Noiseless AI, available as an extra-cost extension to the main Neo program, either as a one-time purchase or by annual subscription. Noiseless AI cannot be purchased on its own. However, Neo with most of its extensions does work as a plug-in for Lightroom and Photoshop.

Being new, Luminar Neo is also updated frequently, with more extensions coming in the next few months.

Version tested: 1.5.0

DxO PureRAW’s simple interface with few choices for Noise Reduction settings.

DxO PureRAW²

Like ON1, DxO makes a full-featured alternative to Adobe’s Lightroom for cataloging and raw developing called DxO PhotoLab, in version 6 as of late 2022. It contains DxO’s Prime and DeepPrime noise reduction routines. However, as with ON1, DxO has spun off just the noise reduction and lens correction parts of PhotoLab into a separate program, PureRAW², which runs either as a stand-alone app or as a plug-in for Lightroom – but not Photoshop, as PureRAW works only on original raw files.

Unlike all the other programs, PureRAW² offers essentially no options to adjust settings, just the option to apply, or not, lens corrections, and to choose the output format. For this testing I applied DeepPrime and exported out to DNG files. [See below for a test of DeepPrimeXD, now offered with PureRaw³.]

Version tested: 2.2

Noise Terminator’s controls allow adjusting strength and detail.

RC-Astro NoiseXTerminator

Unlike the other programs tested, NoiseXTerminator from astrophotographer Russell Croman is designed specifically for deep-sky astrophotography. It installs as a plug-in for Photoshop or Affinity Photo, but not Lightroom. It is also available under the same purchased licence as a “process” for PixInsight, an advanced program popular with astrophotographers, as it is designed just for editing deep-sky images.

I tested the Photoshop plug-in version of Noise XTerminator. It receives occasional updates to both the actual plug-in and separate updates to the AI module.

Version tested: 1.1.2, AI model 2

NIGHTSCAPE TEST

As with the other test images, the panels show a highly magnified section of the image, indicated in the inset. I shot the image of Lake Louise in Banff, Alberta with a Canon RF15-35mm lens on a 45-megapixel Canon R5 camera at ISO 1600.

The test results on a sample nightscape.

Adobe Camera Raw’s basic noise reduction did a good job, but like all general routines it does soften the image as a by-product of smoothing out high-ISO noise.

ON1 NoNoise 2023 retained landscape detail better than ACR but softened the star trails, despite me adding sharpening. It also produced a somewhat patchy noise smoothing in the sky. This was with Luminosity backed off to 75 from the auto setting (which always cranks up the level to 100 regardless of the image), and with the Tack Sharp routine set to 40 with Micro Contrast at 0. It left a uniform pixel-level mosaic effect in the shadow areas. Despite the new Tack Sharp option, the image was softer than with last year’s NoNoise 2022 version (not shown here as it is no longer available) which produced better shadow results.

Topaz DeNoise AI did a better job than NoNoise retaining the sharp ground detail while smoothing noise, always more obvious in the sky in such images. Even so, it also produced some patchiness, with some areas showing more noise than others. This was with the Standard model set to 40 for Noise and Sharpness, and Recover Details at 75. I show the other model variations below.

Topaz Photo AI did a poor job, producing lots of noisy artifacts in the sky and an over-sharpened foreground riddled with colorful speckling. It added noise. This was with the Normal setting and the default Autopilot settings.

Noiseless AI in Luminar Neo did a decent job smoothing noise while retaining, indeed sharpening ground detail without introducing ringing or colorful edge artifacts. The sky was left with some patchiness and uneven noise smoothing. This was with the suggested Middle setting (vs Low and High) and default levels for Noise, Detail and Sharpness. However, I do like Neo (and Skylum’s earlier Luminar AI) for adding other finishing effects to images such as Orton glows.

DxO PureRAW² did smooth noise very well while enhancing sharpness quite a lot, almost too much, though it did not introduce obvious edge artifacts. Keep in mind it offers no chance to adjust settings, other than the mode – I used DeepPrime vs the normal Prime. Its main drawback is that in making the conversion back to a raw DNG image it altered the appearance of the image, in this case darkening the image slightly. It also made some faint star trails look wiggly!

Noise XTerminator really smoothed out the sky, and did so very uniformly without doing much harm to the star trails. However, it smoothed out ground detail unacceptably, not surprising given its specialized training on stars, not terrestrial content.

Conclusion: For this image, I’d say Topaz DeNoise AI did the best, though not perfect, job.

This was surprising, as tests I did with earlier versions of DeNoise AI showed it leaving many patchy artifacts and colored edges in places. Frankly, I was put off using it. However, Topaz has improved DeNoise AI a lot.

Why it works so well, when Topaz’s newer program Photo AI works so poorly is hard to understand. Surely they use the same AI code? Apparently not. Photo AI’s noise reduction is not the same as DeNoise AI.

Similarly, ON1’s NoNoise 2023 did a worse job than their older 2022 version. One can assume its performance will improve with updates. The issue seems to be with the new Tack Sharp addition.

NoiseXTerminator might be a good choice for reducing noise in just the sky of nightscape images. It is not suitable for foregrounds, though as of April 2023 its performance on landscapes has improved but is not ideal.

WIDE-FIELD IMAGE TEST

I shot this image of Andromeda and Triangulum with an 85mm Rokinon RF lens on the 45-megapixel Canon R5 on a star tracker. Stars are now points, with small ones easily mistaken for noise. Let’s see how the programs handle such an image, zooming into a tiny section showing the galaxy Messier 33.

The test results on a sample wide-field deep-sky image.

Adobe Camera Raw’s noise and sharpening routines do take care of the worst of the luminance and chrominance noise, but inevitably leave some graininess to the image. This is traditionally dealt with by stacking multiple sub-exposures.

ON1 NoNoise 2023 did a better job than ACR, smoothing the worst of the noise and uniformly, without leaving uneven patchiness. However, it did soften star images, almost like it was applying a 1- or 2-pixel gaussian blur, adding a slight hazy look to the image. And yet the faintest stars that appeared as just perceptible blurs in the original image were sharpened to one- or two-pixel points. This was with only NoNoise AI applied, and no Tack Sharp AI. And, as I show below, NoNoise’s default “High Detail” option introduced with the 2022 version and included in the 2023 edition absolutely destroys star fields. Avoid it.

ON1 NoNoise “High Detail” option ruins star fields, as shown at right. Use “Original” instead.

Topaz DeNoise AI did a better job than Camera Raw, though it wasn’t miles ahead. This was with the Standard setting. Its Low Light and Severe models were not as good, surprising as you might think one of those choices would be the best for such an image. It pays to inspect Topaz’s various models’ results. Standard didn’t erase stars; it actually sharpened the fainter ones, almost a little too much, making them look like specks of noise. Playing with Enhance Sharpness and Recover Detail didn’t make much difference to this behavior.

Topaz Photo AI again performed poorly. Its Normal mode left lots of noise and grainy artifacts. While its Strong mode shown here did smooth background noise better, it softened stars, wiping out the faint ones and leaving colored edges on the brighter ones.

Noiseless AI in Luminar Neo did smooth fine noise somewhat, better than Camera Raw, but still left a grainy background, though with the stars mostly untouched in size and color.

DxO PureRAW²did eliminate noise quite well, while leaving even the faintest stars intact, unlike with the deep-sky image below, which is odd. However, it added some dark halos to bright stars from over-sharpening. And, as with the nightscape example, PureRAW’s output DNG was darker than the raw that went in. I don’t want noise reduction programs altering the basic appearance of an image, even if that can be corrected later in the workflow.

Noise XTerminator performed superbly, as expected – after all, this is the subject matter it is trained to work on. It smoothed out random noise better than any of the other programs, while leaving even the faintest stars untouched, in fact sharpening them slightly. Details in the little galaxy were also unharmed.

Conclusion: The clear winner was NoiseXTerminator.

Topaz DeNoise was a respectable second place, performing better than it had done on such images in earlier versions. Even so, it did alter the appearance of faint stars which might not be desirable.

ON1 NoNoise 2023 also performed quite well, with its softening of brighter stars yet sharpening of fainter ones perhaps acceptable, even desirable for an effect.

TELESCOPIC DEEP-SKY TEST

I shot this image of the NGC 7822 complex of nebulosity with a SharpStar 61mm refractor, using the red-sensitive 30-megapixel Canon Ra and with a narrowband filter to isolate the red and green light of the nebulas.

Again, the test image is a single raw image developed only to re-balance the color and boost the contrast. No dark frames were applied, so the 8-minute exposure at ISO 3200 taken on a warm night shows thermal noise as single “hot pixel” white specks.

The test results on a sample deep-sky close-up.

Adobe Camera Raw did a good job smoothing the worst of the noise, suppressing the hot pixels but only by virtue of it softening all of the image slightly at the pixel level. However, it leaves most stars intact.

ON1 NoNoise 2023 also did a good job smoothing noise while also seeming to boost contrast and structure slightly. But as in the wide-field image, it did smooth out star images a little, though somewhat photogenically, while still emphasizing the faintest stars. This was with no sharpening applied and Luminosity at 60, down from the default 100 NoNoise applies without fail. One wonders if it really is analyzing images to produce optimum settings. With no Tack Sharp sharpening applied, the results on this image with NoNoise 2023 looked identical to NoNoise 2022.

Topaz DeNoise AI did another good job smoothing noise, while leaving most stars unaffected. However, the faintest stars and hot pixels were sharpened to be more visible tiny specks, perhaps too much, even with Sharpening at its lowest level of 1 in Standard mode. Low Light and Severe modes produced worse results, with lots of mottling and unevenness in the background. Unlike NoNoise, at least its Auto settings do vary from image to image, giving you some assurance it really is responding to the image content.

Topaz Photo AI again produced unusable results. Its Normal modes produced lots of mottled texture and haloed stars. Its Strong mode shown here did smooth noise better, but still left lots of uneven artifacts, like DeNoise AI did in its early days. It certainly seems like Photo AI is using old hand-me-down code from DeNoise AI.

Noiseless AI in Luminar Neo did smooth noise but unevenly, leaving lots of textured patches. Stars had grainy halos and the program increased contrast and saturation, adjustments usually best left for specific adjustment layers dedicated to the task.

DxO PureRAW² did smooth noise very well, including wiping out the faintest specks from hot pixels, but it also wiped out the faintest stars, I think unacceptably and more than other programs like DeNoise AI. For this image it did leave basic brightness alone, likely because it could not apply lens corrections to an image taken with unknown optics. However, it added an odd pixel-level mosaic-like effect on the sky background, again unacceptable.

Noise XTerminator did a great job smoothing random noise without affecting any stars or the nebulosity. The Detail level of 20 I used actually emphasized the faintest stars, but also the hot pixel specks. NoiseXTerminator can’t be counted on to eliminate thermal noise; that demands the application of dark frames and/or using dithering routines to shift each sub-frame image by a few pixels when autoguiding the telescope mount. Even so, Noise XTerminator is so good users might not need to take and stack as many images.

Conclusion: Again, the winner was NoiseXTerminator.

Deep-sky photographers have praised “NoiseX” for its effectiveness, either when applied early on in a PixInsight workflow or, as I do in Photoshop, as a smart filter to the base stacked image underlying other adjustment layers.

Topaz DeNoise is also a good choice as it can work well on many other types of images. But again, play with its various models and settings. Pixel peep!

ON1 NoNoise 2023 did put in a respectable performance here, and it will no doubt improve – it had been out less than a month when I ran these tests.

Based on its odd behavior and results in all three test images I would not recommend DxO’s PureRAW². Yes, it reduces noise quite well, but it can alter tone and color in the process, and add strange pixel-level mosaic artifacts.

COMPARING DxO and TOPAZ OPTIONS

DxO and Topaz DeNoise AI offer the most choices of AI models and strength of noise reduction. Here I compare:

Topaz DeNoise AI on the nightscape image using three of its models: Standard (which I used in the comparisons above), plus Low Light and Severe. These show how the other models didn’t do as good a job.

The set below also compares DeNoise AI to Topaz’s other program, Photo AI, to show how poor a job it is doing in its early form. Its Strong mode does smooth noise but over-sharpens and leaves edge artifacts. Yes, Photo AI is one-click easy to use, but produces bad results – at least on astrophotos.

Comparing DeNoise’s and Photo AI’s different model settings.

As of this writing DxO’s PureRAW² offers the Prime and newer DeepPrime AI models – I used DeepPrime for my tests.

However, DxO’s more expensive and complete image processing program, PhotoLab 6, also offers the even newer DeepPrimeXD model, which promises to preserve or recover even more “Xtra Detail” over the DeepPrime model. As of this writing, the XD mode is not offered in PureRAW². Perhaps that will wait for PureRAW³, no doubt a paid upgrade.

[UPDATE MARCH 2023: DxO has indeed brought out PureRaw³ as a paid upgrade that, as expected, offers the DeepPrimeXD. In testing the new version I found that, while it did not seem to alter an image’s exposure as PureRaw² did, DeepPrime and DeepPrimeXD still unacceptably ruin starry skies, by either adding a fine-scale mosaic effect (DeepPrime) or weird wormy artifacts (DeepPrimeXD). Try it for yourself to see if you find the same.]

Comparing DxO’s various Prime model settings. DeepPrimeXD is only in PhotoLab 6.

The set above compares the three noise reduction models of DxO’s PhotoLab 6. DeepPrime does do a better job than Prime. DeepPrimeXD does indeed sharpen detail more, but in this example it is too sharp, showing artifacts, especially in the sky where it is adding structures and textures that are not real.

However, when used from within PhotoLab 6, the DeepPrime noise reduction becomes more usable. PhotoLab is then being used to perform all the raw image processing, so PureRAW’s alteration of color and tone is not a concern. Conversely, it can also output raw DNGs with only noise reduction and lens corrections applied, essentially performing the same tasks as PureRAW. If you have PhotoLab, you don’t need PureRAW.

APRIL 2023 UPDATE — TESTING ADOBE’S NEW AI Denoise

In April 2023 Adobe updated Lightroom Classic to v12.3 and the Camera Raw plug-in for Bridge and Photoshop to 15.3. The major new feature was a long-awaited AI noise reduction from Adobe called Denoise. It works only on raw files and generates a new raw DNG file to which all the raw develop settings, including AI masks, can be applied. But the DNG file is some four times larger than the original raw file from the camera.

Here’s a comparison of Camera Raw using the old noise reduction and the new AI option, with DxO’s DeepPrimeXD and Topaz’s PhotoAI, on an aurora image from April 23, 2023:

I used Topaz Photo AI as that’s the program Topaz is now putting all their development effort into, neglecting their other plug-ins such as DeNoise AI. I used DxO PhotoLab 6 with its DeepPrimeXD option to export a DNG with only noise reduction applied, for results identical to what is now offered with DxO’s separate PureRaw³ plug-in.

At 100% above, there’s very little obvious difference. They show up when pixel peeping.

400% blow-ups of the sky – Tap or click to download a full-res JPG

Above are 400% blow-ups of a section of the sky.

Compared to using Adobe’s old noise reduction sliders, their new AI Denoise did a far superior job at smoothing noise, and providing sharpening – almost too much, making even the smallest stars pop out more, perhaps a good thing. But there’s no control of that sharpening.

DxO’s DeepPrimeXD provides a similar, or perhaps more excessive level of AI sharpening. While it smooths noise, it introduces all manner of wormy AI artifacts. It is unacceptable.

Topaz PhotoAI’s noise reduction and sharpening, here both applied with their AutoPilot settings, smoothed noise, but created a patchy appearance. It also softened the stars, despite having sharpening turned on. It was the worst of the set.

400% blow-ups of a section of the ground y – Tap or click to download a full-res JPG

In a similar set of blow-ups of the ground, the old Adobe noise reduction did just that — it smoothed only some noise. The new AI Denoise not only smooths noise, it also applies AI-based sharpening, to the point of almost inventing detail. Here it looks believable, but in other tests I have seen it add content, such as structures in the aurora, that looked fake and out of place. Or just plain wrong!

DxO’s DeepPrimeXD’s main feature over the older DeepPrime is the “eXtra Detail” it finds. Here it produces a result similar to Adobe Denoise, though in some areas of this and other images, I find it is over-sharpening. As with Adobe, there is no option for backing off the sharpening. Other than using DeepPrime or Prime noise reduction.

Topaz PhotoAI didn’t do much to add sharpening. If anything, it made the image softer. While PhotoAI has improved with its weekly updates, it still falls far short of the competition, at least for astrophotos and nightscapes.

The bottom line — Adobe’s new AI Denoise can do a superb job on astrophotos, and will be particularly useful for high-ISO nightscapes, perhaps better than any of the competition. But watch what it does! It can invent details or create results that look artificial. Being able to adjust the sharpening would be helpful. Perhaps that will come in an update.

COMPARING AI TO OLDER NON-AI PROGRAMS

The new generation of AI-based programs have garnered all the attention, leaving older stalwart noise reduction programs looking a little forlorn and forgotten.

Here I compare Camera Raw and two of the best of the AI programs, Topaz DeNoise AI and NoiseXTerminator, with two of the most respected of the “old-school” non-AI programs:

Dfine2, included with the Nik Collection of plug-ins sold by DxO (shown above), and

Reduce Noise v9 sold by Neat Image (shown below).

Neat Image’s Reduce Noise control interface – the simple panel.

I tested both by using them in their automatic modes, where they analyze a section or sections of the image and adjust the noise reduction accordingly, but then apply that setting uniformly across the entire image. However, both allow manual adjustments, with Neat Image’s Reduce Noise offering a bewildering array of technical adjustments.

How do these older programs stack up to the new AI generation? Here are comparisons using the same three test images.

Comparing results with Neat Image and Nik Dfine2 on the nightscape test image.

In the nightscape image, Nik Dfine2 and Neat Image’s Reduce Noise did well, producing uniform noise reduction with no patchiness. But the results weren’t significantly better than with Adobe Camera Raw’s built-in routine. Like ACR, both non-AI programs did smooth detail in the ground, compared to DeNoise AI which sharpened the mountain details.

Comparing results with Neat Image and Nik Dfine2 on the wide-field test image.

In the tracked wide-field image, the differences were harder to distinguish. None performed up to the standard of Noise XTerminator, with both Nik Dfine2 and Neat Image softening stars a little compared to DeNoise AI.

Comparing results with Neat Image and Nik Dfine2 on the deep-sky test image.

In the telescopic deep-sky image, all programs did well, though none matched NoiseXTerminator. None eliminated the hot pixels. But Nik Dfine2 and Neat Image did leave wanted details alone, and did not alter or eliminate desired content. However, they also did not eliminate noise as well as did Topaz DeNoise AI or NoiseXTerminator.

The AI technology does work!

YOUR RESULTS MAY VARY

I should add that the nature of AI means that the results will certainly vary from image to image.

In addition, with many of these programs offering multiple models and settings for strength and sharpening, results even from the same program can be quite different. In this testing I used either the program’s auto defaults or backed off those defaults where I thought the effect was too strong and detrimental to the image.

Software is also a constantly moving target. Updates will alter how these programs perform, we hope for the better. For example, two days after I published this test, ON1 updated NoNoise AI to v17.0.2 with minor fixes and improvements.

And do remember I’m testing on astrophotos, and pixel peeping to the extreme. Rave reviews claiming how well even the poor performers here work on “normal” images might well be valid.

This is all by way of saying, your mileage may vary!

So don’t take my word for it. Most programs (Luminar Neo is an exception) are available as free trial copies to test out on your astro-images and in your preferred workflow. Test for yourself. But do pixel peep. That’s where you’ll see the flaws.

WHAT ABOUT ADOBE?

As noted above, with v15.3 of Camera Raw and v12.3 of Lightroom Classic, Adobe finally introduced their contender into the AI noise reduction contest. And it is a very good entry at that.

But it works only on raw files early in the workflow, and it generates a new raw DNG file, one four times the size of the original. The suggestion is that this technology will expand so that the AI noise reduction can be applied later in the workflow to other file formats.

Indeed, in the last couple of years Adobe has introduced several amazing and powerful “Neural Filters” into Photoshop, which work wonders with one click.

Neural network Noise Reduction is coming to Photoshop. One day!

A neural filter for Noise Reduction is on Adobe’s Wait List for development, so perhaps we will see something in the next few months from Adobe, as a version of the AI noise reduction now offered in Lightroom and Camera Raw.

Until then we have lots of choices for third party programs that all improve with every update. I hope this review has helped you make a choice.

— Alan, November 15, 2022 / Revised April 27, 2023 / AmazingSky.com

September 20, 2022September 21, 2022

Testing a Trio of Canon RF Zoom Lenses for Astrophotography

In a detailed review, I test a “holy trinity” of premium Canon RF zoom lenses, with astrophotography the primary purpose.

In years past, zoom lenses were judged inferior to fixed-focal length “prime” lenses for the demands of astrophotography. Stars are the severest test of a lens, revealing optical aberrations that would go unnoticed in normal images, or even in photos of test charts. Many older zooms just didn’t cut it for discerning astrophotographers, myself included.

The new generation of premium zooms for mirrorless cameras, from Canon, Nikon and Sony, are dispelling the old wisdom that primes are better than zooms. The new zooms’ optical performance is proving to be as good, if not better than the older generation of prime lenses for DSLR cameras, models often designed decades ago.

The shorter lens-to-sensor “flange distance” offered by mirrorless cameras, along with new types of glass, provide lens designers more freedom to correct aberrations, particularly in wide-angle lenses.

While usually slower than top-of-the-line primes, the advantage of zoom lenses is their versatility for framing and composing subjects, great for nightscapes and constellation shots. It’s nice to have the flexibility of a zoom without sacrificing the optical quality and speed so important for astrophotography. Can we have it all? The new zooms come close to delivering.

**The “holy trinity” of Canon zooms tested were purchased in 2021 and 2022. From L to R they are: RF15-35mm, RF28-70mm, and RF70-200mm**

A good thing, because with Canon we have little choice! For top-quality glass in wide-angle focal lengths at least, zooms are the only choice for their mirrorless R cameras. As of this writing in late 2022, Canon has yet to release any premium primes for their RF mount shorter than 50mm. Rumours are a 12mm, 24mm, 28mm, and 35mm are coming! But when?

The three zooms I tested are all “L” lenses, designating them as premium-performance models. I have not tested any of Canon’s “economy” line of RF lenses, such as their 24mm and 35mm Macro STM primes. Tests I’ve seen suggest they don’t offer the sharpness I desire for most astrophotography.

Contributing to the lack of choice, top-quality third-party lenses from the likes of Sigma (such as their new 20mm and 24mm Art lenses made for mirrorless cameras) have yet to appear in Canon RF mount versions. Will they ever? In moves that evoked much disdain, Samyang and Viltrox were both ordered by Canon to cease production of their RF auto-focus lenses.

For their mirrorless R cameras, Canon has not authorized any third-party lens makers, forcing you to buy costly Canon L glass, or settle for their lower-grade STM lenses, or opt for reverse-engineered manual-focus lenses from makers such as TTArtisan and Laowa/Venus Optics. While they are good, they are not up to the optical standards of Canon’s L-series glass.

I know, as I own several RF-mount TTArtisan wide-angle lenses and the Laowa 15mm f/2 lens. You can find my tests of those lenses at AstroGearToday.com. Look under Reviews: Astrophotography Gear.

**RF lenses will fit only on Canon R-series mirrorless cameras. This shows the RF15-35mm on the Canon R5 used for the lens testing.**

The trio of RF lenses tested here work on all Canon EOS R-series cameras, including their R7 and R10 cropped-frame cameras. However, they will not work on any Canon DSLRs.

Two of the lenses, the RF15-35mm F/2.8 and RF70-200mm F/4, are designs updated from older Canon DSLR lenses with similar specs. The RF28-70mm F/2 does not have an equivalent focal length range and speed in Canon’s DSLR lens line-up. Indeed, nobody else makes a lens this fast covering the “normal” zoom range.

Together, the three lenses cover focal lengths from 15mm to 200mm, with some overlap. A trio of zooms like this — a wide-angle, normal, and telephoto — is often called a “holy trinity” set, a popular combination all camera manufacturers offer to cover the majority of applications.

However, my interest was strictly for astrophotography, with stars the test subjects.

NOTE: CLICK or TAP on a test image to download a full-resolution image for closer inspection. The images, while low-compression JPGs, are large and numerous, and so will take time to fully load and display. Patience!

METHODOLOGY

I tested the trio of lenses on same-night exposures of a starry but moonlit sky, using the 45-megapixel Canon R5 camera mounted on a motorized star tracker to follow the rotating sky. With one exception noted, any distortion of stars from perfect pinpoints is due to lens aberrations, not star trailing. The brighter moonlit sky helped reveal non-uniform illumination from lens vignetting.

I shot each lens wide-open at its maximum aperture, as well as one stop down from maximum, to see how aberrations and vignetting improved.

I did not test auto-focus performance, nor image stabilization (only the RF28-70mm lacks internal IS), nor other lens traits unimportant for astro work such as bokeh or close focus image quality.

I also compared the RF15-35mm on same-night dark-sky tests against a trio of prime lenses long in my stable: the Rokinon 14mm SP, and Canon’s older L-series 24mm and 35mm primes, all made for DSLRs.

**The lenses each come with lens hoods that use a click-on mechanism much easier to twist on and off than with the older design used on Canon EF lenses.**

TL;DR SUMMARY

Each of the Canon “holy trinity” of zoom performs superbly, though not without some residual lens aberrations such as corner astigmatism and, in the RF28-70mm, slight chromatic aberration at f/2.

However, what flaws they show are well below the level of many older prime lenses made for DSLR cameras.

The RF lenses’ major optical flaw is vignetting, which can be quite severe at some focal lengths, such as in the RF70-200mm at 200mm. But this flaw can be corrected in processing.

These are lenses that can replace fixed-focal length primes, though at considerable cost, in part justifiable in that they negate the need for a suite of many prime lenses.

The performance of these and other new lenses made for mirrorless cameras from all brands is one good reason to switch from DSLR to mirrorless cameras.

Lens Specs and Applications

Canon RF15-35mm F/2.8 L IS USM

**The RF15-35mm is a fine nightscape lens. It extends slightly when zooming with the lens physically longest at its shortest 15mm focal length.**

The Canon RF15-35mm F/2.8 L is made primarily for urban photography and landscapes by day. My main application is using it to take landscapes by night, and auroras, where its relatively fast f/2.8 speed helps keeps exposure times short and ISO speeds reasonably low. However, the RF15-35mm can certainly be used for tracked wide-angle Milky Way and constellation portraits.

The lens weighs a moderate 885 grams (31 ounces or 1.9 pounds) with lens hood and end caps, and accepts 82mm filters, larger than the 72mm or 77mm filter threads of most astrophoto-friendly lenses. Square 100mm filters will work well on the lens, even at the 15mm focal length. There are choices, such as from KASE, for light pollution reduction and star diffusion filters in this size and format. I have reviews of these filters at AstroGearToday.com, both here for light pollution filters and here for starglow filters.

Canon offers a lower-cost alternative in this range, their RF14-35mm. But it is f/4, a little slow for nightscape, aurora, and Milky Way photography. I have not tested one.

Canon RF28-70mm F/2 L USM

**The RF28-70mm works great for tracked starfields and constellations. It extends when zooming, with it longest at its 70mm focal length.**

The big Canon RF28-70mm F/2 is aimed at wedding and portrait photographers, though the lens is suitable for landscape work. While I do use it for nightscapes, my primary use is for tracked Milky Way and constellation images, where its range of fields of view nicely frames most constellations, from big to small.

I justified its high cost by deciding it replaces (more or less!) prime lenses in the common 24mm, 35mm, 50mm, and 85mm focal lengths. Its f/2 speed does bring it into fast prime lens territory. It’s handy to have just one lens to cover the range.

Canon offers a lower-cost alternative here, too, their RF24-70mm. But it is f/2.8. While this is certainly excellent speed, I like having the option of shooting at f/2. An example is when using narrowband nebula filters such as red hydrogen-alpha filters, where shooting at f/2 keeps exposures shorter and/or ISOs lower when using such dense filters. I use this lens with an Astronomik 12-nanometre H-α clip-in filter. An example is in one of the galleries below.

While a clip-in filter shifts the infinity focus point inward (to as close as the 2-metre mark with the RF28-70mm at 28mm, and to 6 metres at 70mm), I did not find that shift adversely affected the lens’s optical performance. That’s not true of all lenses.

Make no mistake, the RF28-70mm is one hefty lens, weighing 1530 grams (54 ounces or 3.4 pounds). Its front-heavy mass demands a solid tripod head. Its large front lens accepts big 95mm filters, a rare size with few options available. I found one broadband light pollution filter in this size, from URTH. Otherwise, you need to use in-body clip-in filters. Astronomik makes a selection for Canon EOS R cameras.

Canon RF70-200mm F/4 L IS USM

**The RF70-200mm works well for closeups of landscape scenes such as moonrises. It extends the most of all the lenses when zooming to its longest focal length.**

The Canon RF70-200mm F/4 is another portrait or landscape lens. I use it primarily for bright twilight planet conjunctions and moonrise scenes, where its slower f/4 speed is not a detriment. However, as my tests show, it can be used for tracked deep-sky images, where it is still faster than most short focal length telescopes.

The RF70-200mm lens weighs 810 grams (28 ounces, or 1.75 pounds) with lens hood and caps, so is light for a 70-to-200mm zoom. It is also compact. At just 140mm long when set to 70mm, it is actually the shortest lens of the trio. However, the barrel extends to 195mm long when zoomed out to 200mm focal length.

Canon offers the more costly and, at 1200 grams, heavier RF70-200mm F/2.8 lens which might be a better choice for deep-sky imaging where the extra stop of speed can be useful. But in this case, I chose the slower, more affordable – though still not cheap – f/4 version. It accepts common 77mm filters, as does the f/2.8 version.

Centre Sharpness

Canon RF15-35mm F/2.8 L IS USM

**This compares 400% blow-ups of the frame centres at the two extreme focal lengths and at two apertures: wide open at f/2.8 and stopped down to f/4.**

Like the other two zoom lenses tested, the RF15-35mm is very sharp on axis. Even wide open, there’s no evidence of softness and star bloat from spherical aberration, the bane of cheaper lenses.

Coloured haloes from longitudinal chromatic aberration are absent, except at 28mm and 35mm (shown here) when wide open at f/2.8, where bright stars show a little bit of blue haloing. At f/4, this minor level of aberration disappears.

Canon RF28-70mm F/2 L USM

**This compares 400% blow-ups of the frame centres at the two extreme focal lengths and at two apertures: wide open at f/2 and stopped down to f/2.8.**

The big RF28-70mm is also very sharp on-axis but is prone to more chromatic aberration at f/2, showing slight magenta haloes on bright stars at the shorter focal lengths and pale cyan haloes at 70mm in my test shots. Such false colour haloes can be very sensitive to precise focus, though with refractive optics the point of least colour is often not the point of sharpest focus.

At f/2, stars are a little softer at 70mm than at 28mm. Stopping down to f/2.8 eliminates this slight softness and most of the longitudinal chromatic aberration.

Canon RF70-200mm F/4 L IS USM

**This compares 400% blow-ups of the frame centres at the two extreme focal lengths and at two apertures: wide open at f/4 and stopped down to f/5.6.**

Unlike prime telephotos I’ve used, the RF70-200mm shows negligible chromatic aberration on-axis at all focal lengths, even at f/4. Stars are a little softer at the longest focal length at f/4, perhaps from slight spherical aberration, though my 200mm test shots are also affected by a little mistracking, trailing the stars slightly.

Stopping down to f/5.6 sharpens stars just that much more at 200mm.

Corner Aberrations

The corners are where we typically separate great lenses from the merely good. And it is where zoom lenses have traditionally performed badly. For example, my original Canon EF16-35mm f/2.8 lens was so bad off-axis I found it mostly unusable for astro work. Not so the new RF15-35mm, which is the RF replacement for Canon’s older EF16-35mm.

To be clear – in these test shots you might think the level of aberrations are surprising for premium lenses. But keep in mind, to show them at all I am having to pixel-peep by enlarging all the test images by 400 percent, cropping down to just the extreme corners.

Check the examples in the Compared to DSLR Lenses section and in the Finished Images Galleries for another look at lens performance in broader context.

Canon RF15-35mm F/2.8 L IS USM

**This compares 400% blow-ups of the extreme corners at five focal lengths with the RF15-35mm wide open at f/2.8**

Surprisingly, this RF’s best performance off-axis is actually at its shortest focal length. At 15mm it exhibits only some slight tangential astigmatism, elongating stars away from the frame centre. At 24mm aberrations appear slightly worse than at the other focal lengths, showing some flaring from sagittal astigmatism and perhaps coma as well, aberrations seen to a lesser degree at 28mm and 35mm, making stars look like little three-pointed triangles.

**This compares 400% blow-ups of the extreme corners at five focal lengths with the RF15-35mm stopped down one stop to f/4.**

The aberrations reduce when stopped down to f/4, but are still present, especially at 24mm, this lens’s weakest focal length, though only just.

While the RF15-35mm isn’t perfect, it outperforms other prime lenses I have, and that I suspect most users will own or have used in the past with DSLRs. Only new wide-angle premium primes for the RF mount, if and when we see them, will provide better performance.

Canon RF28-70mm F/2 L USM

**This compare 400% blow-ups of the extreme corners at four focal lengths with the RF28-70mm wide open at f/2.**

The RF28-70mm’s fast f/2 speed, unusual for any zoom lens, was surely a challenge to design for. Off-axis when wide open at f/2 it does show astigmatism at the extreme corners at all focal lengths, but the least at 50mm, and the worst at 28mm where a little lateral chromatic aberration is also visible, adding slight colour fringing.

**This compare 400% blow-ups of the extreme corners at four focal lengths with the RF28-70mm stopped down one stop to f/2.8.**

Sharpness off-axis improves markedly when stopped down one stop to f/2.8, where at 50mm stars are now nearly perfect to the corners. Indeed, performance is so good at 50mm, I think there would be little need to buy the Canon RF50mm prime, unless its f/1.2 speed is deemed essential.

With the RF28-70mm at f/2.8, stars still show some residual astigmatism at 28mm and 35mm, but only at the extreme corners.

Canon RF70-200mm F/4 L IS USM

**This compare 400% blow-ups of the extreme corners at four focal lengths with the RF70-200mm wide open at f/4.**

The RF70-200mm telephoto zoom shows some astigmatism and coma at the corners when wide open at f/4, with it worse at the shorter focal lengths. While lens corrections have been applied here, the 200mm image still shows a darker corner from the vignetting described below.

**This compare 400% blow-ups of the extreme corners at four focal lengths with the RF70-200mm stopped down one stop to f/5.6.**

Stopping down to f/5.6 eliminates most of the off-axis aberrations at 135mm and 200mm focal lengths but some remain at 70mm and to a lesser degree at 100mm.

This is a lens that can be used at f/4 even for the demands of deep-sky imaging, though perfectionists will want to stop it down. At f/5.6 it is similar in speed to many astrographic refractors, though most of those start at about 250mm focal length.

Frame Vignetting

In the previous test images, I applied lens corrections (but no other adjustments) to each of the raw files in Adobe Camera Raw, using the settings ACR automatically selects from its lens database. These corrections brightened the corners.

In this next set I show the lenses’ weakest point, their high level of vignetting. This light falloff darkens the corners by a surprising amount. In the new generation of lenses for mirrorless cameras, it seems lens designers are choosing to sacrifice uniform frame illumination in order to maximize aberration corrections. The latter can’t be corrected entirely, if at all, by software.

However, corrections applied either in-camera or at the computer can brighten corners, “flattening” the field. I show that improvement in the section that follows this one.

Canon RF15-35mm F/2.8 L IS USM

**This compares the level of vignetting present in the RF15-35mm without the benefit of lens corrections, showing the difference at five focal lengths.**

In the wide-angle zoom, vignetting darkens just the corners at 15mm, but widens to affect progressively more of the frame at the longer focal lengths. The examples show the entire right side of the frame. I show the effect just at f/2.8.

Though I don’t show examples with the two wider zooms, with all lenses vignetting decreases dramatically when each lens is stopped down by even one stop. The fields become much more evenly illuminated, though some darkening at the very corners remains one stop down.

Canon RF28-70mm F/2 L USM

**This compares the level of vignetting present in the RF28-70mm without the benefit of lens corrections, showing the difference at four focal lengths.**

In this “normal” zoom, vignetting performance is similar at all focal lengths, though it affects a bit more of the field at 70mm than at 28mm. Again, while I’m not presenting an example, vignetting decreases a lot when this lens is stopped down to f/2.8. While the extra stop of speed is certainly nice to have at times, I usually shoot the RF28-70mm at f/2.8.

Canon RF70-200mm F/4 L IS USM

**This compares the level of vignetting present in the RF70-200mm without the benefit of lens corrections, showing the difference at four focal lengths.**

In this telephoto zoom, vignetting is fairly mild at the shorter focal lengths but becomes severe at 200mm, affecting much of the field. It is far worse than I see with my older Canon EF200mm f/2.8 prime, a lens that is not as sharp at f/4 as the RF zoom.

The faster RF70-200mm f/2.8 lens, which I had the chance to test one night last year, showed as much, if not more, vignetting than the f/4 version. See my test here at AstroGearToday.com. I thought the f/4 version would be better for vignetting, but it is not.

**This shows how much the RF-70-200mm’s vignetting improves when it is stopped down.**

In this case, as the vignetting is so prominent at 200mm, I show above how much it improves when stopped down to f/5.6, in a comparison with the lens at f/4, both with no lens corrections applied in processing. The major improvement comes from the smaller aperture alone. For twilight scenes, I’d suggest stopping this lens down to better ensure a uniform sky background.

LENS Corrections

In this next set I show how well applying lens corrections improves the vignetting at the focal lengths where each of the lenses is at its worse, and with each at its widest aperture.

I show this with Adobe Camera Raw but Lightroom would provide identical results. I did not test lens corrections with other programs such as CaptureOne, DxO PhotoLab, or ON1 Photo Raw, which all have automatic lens corrections as well.

Canon RF15-35mm F/2.8 L IS USM

**This compare the RF15-35mm lens at f/2.8 and 35mm with and without lens corrections applied, to show how much they improve the vignetting.**

Applying lens corrections in Adobe Camera Raw certainly brightened the corners and edges, though still left some darkening at the very corners that can be corrected by hand in the Manual tab.

Canon RF28-70mm F/2 L USM

**This compare the RF28-70mm lens at f/2 and 70mm with and without lens corrections applied, to show how much they improve the vignetting.**

ACR’s lens corrections helped but did not completely eliminate the vignetting here. Corner darkening remained. Manually increasing the vignetting slider can provide that extra level of correction needed.

Canon RF70-200mm F/4 L IS USM

**This compare the RF70-200mm lens at f/4 and 200mm with and without lens corrections applied, to show how much they improve the vignetting.**

The high level of vignetting with this lens at 200mm largely disappeared with lens corrections, though not entirely. For deep-sky imaging, users might prefer to shoot and apply flat-field frames. I prefer to apply automatic and manual corrections to the raw files, to stay within a raw workflow as much as possible.

Same Focal Length Comparisons

With the trio of lenses offering some of the same focal lengths, here I show how they compare at three of those shared focal lengths. I zoom into the upper right corners here, as with the Corner Aberrations comparisons above.

RF15-35mm vs. RF28-70mm at 28mm

**This compares the RF15-35mm at 28mm to the RF28-70mm also at 28mm and with both at f/2.8.**

With both lenses at 28mm and at the same f/2.8 aperture (though the RF28-70mm is now stopped down one stop), it’s a toss up. Both show corner aberrations, though of a different mix, distorting stars a little differently. The RF28-70mm shows some lateral chromatic aberration, but the RF15-35mm shows a bit more flaring from astigmatism.

RF15-35mm vs. RF28-70mm at 35mm

**This compares the RF15-35mm at 35mm to the RF28-70mm also at 35mm and with both at f/2.8.**

The story is similar with each lens at 35mm. Stars seem a bit sharper in the RF15-35mm though are elongated more by astigmatism at the very corners. Lens corrections have been applied here and with the other two-lens comparison pairs.

RF28-70mm vs. RF70-200mm at 70mm

**This compares the RF28-70mm at 70mm and f/2.8 to the RF70-200mm also at 70mm but wide open at f/4.**

Here I show the RF28-70mm at f/2.8 and the RF70-200mm wide open at f/4, with both set to 70mm focal length. The telephoto lens shows a little more softening and star bloating from corner aberrations, though both perform well.

Compared to DSLR Lenses

Here I try to demonstrate just how much better at least one of the zooms on test here is compared to older prime lenses made for DSLRs. The Canon lenses are labeled EF, for Canon’s EF lens mount used for decades on their DSLRs and EOS film cameras. Both are premium L lenses.

I shot this set on a different night than the previous examples, with some light cloud present which added various amounts of glows around stars. But the test shots still show corner sharpness and aberrations well, in this case of the upper left corners of all frames.

Canon RF15-35mm at 35mm vs. Canon EF35mm L

**This compares the RF15-35mm zoom at 35mm to the older EF35mm L prime lens**. **Some light cloud added the glows at right.**

The Canon EF35mm is the original Mark I version, which Canon replaced a few years ago with an improved Mark II model. So I’m sure if you were to buy an EF35mm lens now (or if that’s the model you own) it will perform better than what I show here.

Both lenses are at f/2.8, wide open for the RF lens, but stopped down two stops for the f/1.4 EF lens.

The zoom lens is much sharper to the corners, with far less astigmatism and none of the lateral chromatic aberration and field curvature (softening stars at the very corner) of the old EF35mm prime. I thought the EF35mm was a superb lens, and used it a lot over the last 15 years for Milky Way panoramas. I would not use it now!

Canon RF15-35mm at 24mm vs. Canon EF24mm L

**This compares the RF15-35mm zoom at 24mm to the older EF24mm L prime lens.** **Some light cloud added the glows at right.**

Bought in the early years of DSLRs, the EF24mm tested here is also an original Mark I model, since replaced by an improved Mark II 24mm. The old 24mm is good, but shows more astigmatism than the RF lens, and some field curvature and purple chromatic aberration not present at all in the RF lens.

And this is comparing it to the RF lens at its weakest focal length, 24mm. It still handily outperforms the old EF24mm prime.

Canon RF15-35mm at 15mm vs. Rokinon 14mm SP

**This compares the RF15-35mm at 15mm to the Rokinon 14mm SP prime lens.**

Canon once made an EF14mm f/2.8 L prime, but I’ve never used it. For a lens in this focal length, one popular with nightscape photographers, I’ve used the ubiquitous Rokinon/Samyang 14mm f/2.8 manual lens. While a bargain at about $300, I always found it soft and aberrated at the corners. See my test of 14mm ultra-wides here.

A few years ago I upgraded to the Rokinon 14mm f/2.4 lens in their premium SP series (about $800 for the EF-mount version). While a manual lens, it does have electrical contacts to communicate lens metadata to the camera. Like all EF-mount lenses from any brand, it can be adapted to Canon R cameras using Canon’s $100 EF-EOS R lens adapter.

**Older DSLR lenses like the Rokinon SP can be adapted to all Canon R cameras with the Canon lens adapter ring which transmits lens data to the camera.**

The Rokinon SP is the only prime I found that beat the RF zoom. It provided sharper images to the corners than the RF15-35mm at 15mm. The Rokinon also offers the slightly faster maximum aperture of f/2.4 (which Canon cameras register as f/2.5). Vignetting is severe, but like the RF lenses can be corrected – Camera Raw has this lens in its database. What is not so easy to correct is some slight colour shift at the corners.

Another disadvantage, as with many other 14mm lenses, is that the SP lens cannot accept front-mounted filters. The RF15-35mm can.

Nevertheless, until Canon comes out with a 12mm to 14mm RF prime, or allows Sigma to, an adapted Rokinon 14mm SP is a good affordable alternative to the RF15-35mm.

**The RF15-35mm (left) takes 82mm filters, the RF28-70mm (centre) requires 95mm filters, but the RF70-200mm (right) can accept common 77mm filters.**

Mechanical Points

All the RF lens bodies are built of weight-saving engineered plastic incorporating thorough weather sealing. There is nothing cheap about their fit, finish or handling. Each lens has textured grip rings for the zoom, focus and a control ring that can be programmed to adjust either aperture, ISO, exposure compensation or other settings of your choosing.

As with all modern auto-focus lenses, the manual focus ring on each lens does not mechanically move glass. It controls a motor that in turn focuses the lens, so-called “focus-by-wire.” However, I found that focus could be dialled in accurately. But if the camera is turned off, then on again, the lens will not return to its previous focus position. You have to refocus to infinity each time the camera is powered up, a nuisance.

Unlike some Nikon, Sony, Samyang, and Sigma lenses, none of the Canon lenses have a focus lock button, or any way of presetting an infinity focus point, or simply having the lens remember where it was last set. I would hope Canon could address that deficiency in a firmware update.

With all the zooms, I did not find any issue with “zoom creep.” The telescoping barrels remained in place during long exposures and did not slowly retract when aimed up. While the RF28-70mm and RF70-200mm each have a zoom lock switch, it locks the lens only at its shortest focal length.

Each lens is parfocal within its zoom range. Focus at one zoom position, and it will be in focus for all the focal lengths. I usually focus at the longest focal length where it is easiest to judge focus by eye, then zoom out to frame the scene.

FINISHED IMAGES GALLERIES

Here I present a selection of final, processed images (four for each lens), so you can better see how each performs on real-world celestial subjects. To speed download, the images are downsized to 2048 pixels wide.

As per my comments at top, the RF15-35mm is my primary nightscape lens, the RF28-70mm my lens for wide-field constellation and Milky Way shots, while the RF70-200mm is for conjunctions and Moon scenes. It would also be good for eclipses.

Image Gallery with Canon RF15-35mm F/2.8 L IS USM

Image Gallery with Canon RF28-70mm F/2 L USM

Image Gallery with Canon RF70-200mm F/4 L IS USM

Click on the images to bring them up full screen with caption information.

CONCLUSIONs and recommendations

If you are a Canon user switching from your aging but faithful DSLR to one of their mirrorless R cameras, each of these lenses will perform superbly for astrophotography. At a price! Each is costly. But the cost of older EF lenses has also increased in recent months.

The other native RF L-series lenses in this focal length range, Canon’s RF50mm and RF85mm f/1.2 primes, are stunning … but also expensive. As I’m sure any coming RF wide-angle L primes will be, if and when they ever appear!

**This shows the relative difference in size and height of the lens trio, with all collapsed to their minimum size.**

The cheaper alternative – not the least because you might already own them! – is using adapted EF-mount lenses made for DSLRs, either from Canon or other brands. But in many cases, as I’ve shown, the new RF glass is sharper, especially when on a high-resolution camera such as the Canon R5 I used for all the testing.

And there’s the harsh reality that Canon is discontinuing many EF lenses. You can now buy some only used. For example, the EF135mm f/2 L and EF200mm f/2.8 L are both gone.

Until Canon licenses other companies to issue approved lenses for their RF mount – if that happens at all – our choices for native RF lenses are limited. However, the quality of Canon’s L lenses is superb. I now use these zooms almost exclusively, and financed most of their considerable cost by selling off a ream of older cameras and lenses.

If there’s one lens to buy for most astrophotography, it might be the big RF28-70mm F/2, a zoom lens that comes close to offering it all: flexibility, optical quality and speed. The RF24-70mm F/2.8 is a more affordable choice, though I have not tested one.

If nightscapes are the priority, the RF15-35mm F/2.8 would see a lot of use, as perhaps the only lens you’d need.

Of the trio, the RF70-200mm was the lowest priority on my wish list. But it has proven to be very useful for framing horizon scenes.

The superb optics of these and other new lenses made for mirrorless cameras is one good reason to upgrade from a DSLR to a mirrorless camera, in whatever brand you prefer.

June 22, 2022June 23, 2022

Testing the Canon R5 for Astrophotography

In a format similar to my other popular camera tests, I put the 45-megapixel Canon R5 mirrorless camera through its paces for the demands of astrophotography.

In a sequel to my popular post from September 2021 where I reviewed the Canon R6 mirrorless camera, here is a similar test of its higher-megapixel companion, the Canon R5. Where the R6 has a modest 20-megapixel sensor with relatively large 6.6-micron pixels, the R5 is (at present) Canon’s highest megapixel camera, with 45 megapixels. Each pixel is only 4.4 microns across, providing higher resolution but risking more noise.

Is the higher noise noticeable? If so, does that make the R5 less than ideal for astrophotography? To find out, I tested an R5 purchased locally in Calgary from The Camera Store in May 2022.

NOTE: CLICK orTAP on any image to bring it up full screen for closer inspection. The blog contains a lot of high-res images, so they may take a while to all load. Patience! Thanks!

**The Canon R5 uses a full-frame sensor offering 45 megapixels, producing images with 8192 x 5464 pixels, and making 8K video possible.**

TL;DR Summary

The Canon R5 proved to be surprisingly low in noise, and has worked very well for nightscape, lunar and deep-sky photography (as shown below), where its high resolution does produce a noticeable improvement to image detail, with minimal penalty from higher noise. Its 8K video capability has a place in shooting the Moon, Sun and solar eclipses. It was not so well suited to shooting videos of auroras.

This is a stack of 12 x 5-minute exposures with a Sharpstar 94EDPH refractor at f/4.5 and the Canon R5 at ISO 800, taken as a test of the R5 for deep-sky imaging. No filters were employed. Close-ups of sub-frames from this shoot with the R5, and also with the R6 and Ra, are used throughout the review.

R5 Pros

The Canon R5 is superb for its:

High resolution with relatively low noise
ISO invariant sensor performance for good shadow recovery
Good live view display with ISO boost in Movie mode
8K video has its attraction for eclipse photography
Good top LCD information screen missing in the R6
No magenta edge “amp glow” that the R6 shows
Higher 6x and 15x magnifications for precise manual focusing
Good battery life
Pro-grade Type N3 remote port

R5 Cons

The Canon R5 is not so superb for its:

Noise in stills and movies is higher than in the R6
Propensity for thermal-noise hot pixels in shadows
Not so suitable for low-light video as the R6
Overheating in 8K video
Live View image is not as bright as in the R6’s Movie mode
High cost!

**The flip-out screen of the R5 (and all recent Canon cameras) requires an L-bracket with a notch in the side (a Small Rig unit is shown here) to accommodate the tilting screen.**

CHOOSING THE R5

Since late 2019 my main camera for all astrophotography has been the Canon Ra, a limited-edition version of the original R, Canon’s first full-frame mirrorless camera that started the R series. The Ra had a special infra-red cutoff filter in front of the sensor that passed a higher level of visible deep-red light, making it more suitable for deep-sky astrophotography than a standard DSLR or DSLM (mirrorless) camera. The Ra was discontinued after two years on the market, a lifetime similar to Canon’s previous astronomical “a” models, the 20Da and 60Da.

I purchased the Canon R6 in late 2021, primarily to use it as a low-light video camera for aurora photography, replacing the Sony a7III I had used for several years and reviewed here. Over the last year, I sold all my non-Canon cameras, as well as the Canon 6D MkII DSLR (reviewed here), to consolidate my camera gear to just Canon mirrorless cameras and lenses.

The R6 has proven to be an able successor to the Sony for me, with the R6’s modest megapixel count and larger pixels making it excellent for low-light video. But the higher resolution of the R5 was still attractive. So I have now added it to my Canon stable. Since doing so, I have put it through several of my standard tests to see how suitable it is for the demands of astrophotography, both stills and video.

Here are my extensive results, broken down by various performance criteria. I hope you will find my review useful in helping you make a purchase decision.

LIVE VIEW FRAMING

**This compares the back-of-camera views of the R5 vs. the R6, with both set to their highest ISO in Movie mode for the brightest preview image.**

First, why go mirrorless at all? For astrophotography, the big difference compared to even a high-end DSLR, is how much brighter the “Live View” image is when shooting at night. DSLM cameras are always in Live View – even the eye-level viewfinder presents a digital image supplied by the sensor.

And that image is brighter, often revealing more than what a DSLR’s optical viewfinder can show, a great advantage for framing nightscape scenes, and deep-sky fields at the telescope.

The R5 certainly presents a good live view image. However, it is not as bright nor as detailed as what the R6 can provide when placed in its Movie mode and with the ISO bumped up to the R6’s highest level of ISO 204,800, where the Milky Way shows up, live!

The R5 only goes as high as ISO 51,200, and so as I expected it does not provide as bright or detailed a preview at night as the R6 can. However, the R5 is better than the original R for live-view framing, and better than any Canon DSLR I’ve used.

LIVE VIEW FOCUSING

As with other Canon mirrorless cameras, the R5 offers a Focus Assist overlay (top) to aid manual focusing. It works on bright stars. It also has a 6x and 15x magnifications for even more precise focusing.

Like the R6, the R5 can autofocus accurately on bright stars and planets. By comparison, while the Ra can autofocus on distant bright lights, it fails on bright stars or planets.

Turning on Focus Peaking makes stars turn red, yellow or blue (your choice of colours) when they are in focus, as a reassuring confirmation.

**Turning on Focus Guide provides the arrowed overlays shown above.**

In manual focus, an additional Focus Aid overlay, also found in the R6, provides arrows that close up and turn green when in focus on a bright star or planet.

Or, as shown above, you can zoom in by 6x or 15x to focus by eye the old way by examining the star image. These are magnification levels higher than the 5x and 10x of the R6 and most other Canon cameras, and are a great aid to precise focusing, necessary to make full use of the R5’s high resolution, and the sharpness of Canon’s RF lenses. The 15x still falls short of the Ra’s 30x for ultra-precise focusing on stars, but it’s a welcome improvement nonetheless.

In all, while the R5 is not as good as the R6 for framing in low light, it is better for precise manual focusing using its higher 15x magnification.

NOISE PERFORMANCE — NIGHTSCAPES

The key camera characteristic for astrophoto use is noise. There is no point in having lots of resolution if, at the high ISOs we use for most astrophotography, the detail is lost in noise. But I was pleasantly surprised that proved not to be the case with the R5.

As I show below, noise is well controlled, making the R5 usable for nightscapes at ISOs up to 3200, if not 6400 when needed in a pinch.

**This compares the noise on a dark nightscape at the typical ISOs used for such scenes. A level of noise reduction shown has been applied in Camera Raw.**

With 45 megapixels, at the upper end of what cameras offer today, the R5 has individual pixels, or more correctly “photosites,” that are each 4.4 microns in size, the “pixel pitch.”

This is still larger than the 3.7-micron pixels in a typical 24-megapixel cropped-frame camera like the Canon R10, or the 3.2-micron pixels found in a 32-megapixel cropped-frame camera like the Canon R7. Both are likely to be noisier than the R5, though will provide even higher resolution, as well as greater magnification with any given lens or telescope.

By comparison, the 30-megapixel full-frame R (and Ra) has a pixel pitch of 5.4 microns, while the 20-megapixel R6’s pixel pitch is a generous 6.6 microns. Only the 12-megapixel Sony a7SIII has larger 8.5-micron pixels, making it the low-light video champ.

The bigger the photosites (i.e. the larger the pixel pitch), the more photons each photosite can collect in a given amount of time – and the more photons they can collect, period, before they overfill and clip highlights. More photons equals more signal, and therefore a better signal-to-noise ratio, while the greater “full-well depth” yields higher dynamic range.

However, each generation of camera improves the signal-to-noise ratio by suppressing noise via its sensor design and improved signal processing hardware and firmware. The R5 and R6 each use Canon’s latest DIGIC X processor.

**This compares the R5 to the R6 and Ra cameras at the high ISOs of 3200 and 6400 often used for Milky Way nightscapes.**

In nightscapes the R5 did show more noise at high ISOs, especially at ISO 6400, than the R6 and Ra, but the difference was not large, perhaps one stop at most, if that. What was noticeable was the presence in the R5 of more hot pixels from thermal noise, as described later.

**This compares the R5 to the R6 and Ra cameras at the more moderate ISOs of 800 and 1600 used for brighter nightscapes.**

At slower ISOs the R5 showed a similar level of noise as the R6 and Ra, but a finer-grained noise than the R6, in keeping with the R5’s smaller pixels. In this test set, the R5 did not exhibit noticeably more noise than the other two cameras. This was surprising.

NOTE: In these comparisons I have not resampled the R5 images down to the megapixel count of the R6 to equalize them, as that’s not what you would do if you bought an R5. Instead, I have magnified the R6 and Ra’s smaller images so we examine the same area of each camera’s images.

As with the R6, I also saw no “magic ISO” setting where the R5 performed better than at other settings. Noise increased in proportion to the ISO speed. The R5 proved perfectly usable up to ISO 3200, with ISO 6400 acceptable for stills when necessary. But I would not recommend the R5 for those who like to shoot Milky Way scenes at ISO 12,800.

For nightscapes, a good practice that would allow using lower ISO speeds would be to shoot the sky images with a star tracker, then take separate long untracked exposures for the ground.

NOTE: In my testing I look first and foremost at actual real-world results. For those interested in more technical tests and charts, I refer you to DxOMark’s report on the Canon R5.

NOISE PERFORMANCE — DEEP-SKY

This compares the R5 at the typical ISO settings used for deep-sky imaging, with no noise reduction applied to the raw files for this set. The inset shows the portion of the frame contained in the blow-ups.

Deep-sky imaging with a tracking mount is more demanding, due to its longer exposures of up to several minutes for each “sub-frame.”

On a series of deep-sky exposures through a telescope, above, the R5 again showed quite usable images up to ISO 1600 and 3200, with ISO 6400 a little too noisy in my opinion unless a lot of noise reduction was applied or many images were shot to stack later.

**This compares the R5 to the R6 and Ra cameras at ISO 6400, higher than typically used for deep-sky imaging. No noise reduction was applied to the raw files.**

As with the nightscape set, at high ISOs, such as at ISO 6400, the R5 did show more noise than the R6 and Ra, as well as more colour splotchiness in the dark sky, and lower contrast. The lower dynamic range of the R5’s smaller pixels is evident here.

Just as with nightscapes, the lesson with the R5 is to keep the ISO low if at all possible. That means longer exposures with good auto-guiding, but that’s a best practice with any camera.

**This compares the R5 to the R6 and Ra cameras at the lower ISOs of 800 and 1600 best for deep-sky imaging, for better dynamic range. No noise reduction was applied to the raw files.**

At lower ISOs that provide better dynamic range, shown above, the difference in noise levels between the three cameras was not that obvious. Each camera presented very similar images, with the R6 having a coarser noise than the Ra and R5.

In all, I was surprised the R5 performed as well as it did for deep-sky imaging. See my comments below about its resolution advantage.

ISO INVARIANCY

The flaw in many Canon DSLRs, one documented in my 2017 review of the 6D Mark II, was their poor dynamic range due to the lack of an ISO invariant sensor design.

Canon R-series mirrorless cameras have largely addressed this weakness. As with the R and R6, the sensor in the R5 appears to be nicely ISO invariant.

Where ISO invariancy shows itself to advantage is on nightscapes where the starlit foreground is often dark and underexposed. Bringing out detail in the shadows in raw files requires a lot of Shadow Recovery or increasing the Exposure slider. Images from an ISO invariant sensor can withstand the brightening “in post” far better, with minimal noise increase or degradations such as a loss of contrast, added banding, or horrible discolourations.

**This shows the same scene with the R5 progressively underexposed by shooting at a lower ISO then boosted in exposure in Adobe Camera Raw.**

As I do for such tests, I shot sets of images at the same shutter speed, one well-exposed at a high ISO, then several at successively lower ISOs to underexpose by 1 to 4 stops. I then brightened the underexposed images by increasing the Exposure in Camera Raw by the same 1 to 4 stops. In an ideal ISO invariant sensor, all the images should look the same.

The R5 performed well in images underexposed by up to 3 stops. Images underexposed by 4 stops started to fall apart with low contrast and a magenta cast. This was worse performance than the R6, which better withstood underexposure by as much as 4 stops, and fell apart at 5 stops of underexposure.

While it can withstand underexposure, the lesson with the R5 is to still expose nightscapes as well as possible, likely requiring a separate longer exposure for the dark ground. Expose to the right! Don’t depend on being able to save the image by brightening “in post.” But again, that’s a best practice with any camera.

THERMAL NOISE

Here I repeat some of the background information from my R6 review. But it bears repeating, as even skilled professional photographers often misunderstand the various forms of noise and how to mitigate them.

All cameras will exhibit thermal noise in long exposures, especially on warm nights. This form of heat-induced noise peppers the shadows with bright or “hot” pixels, often brightly coloured.

This is not the same as the shot and read noise that adds graininess to high-ISO images and that noise reduction software can smooth out later in post.

Thermal noise is more insidious and harder to eliminate in processing without harming the image. However, Monika Deviat offers a clever method here at her website.

I found the R5 was prone to many hot pixels in long nightscape exposures where they show up in dark, underexposed shadows. I did not find a prevalence of hot pixels in well-exposed deep-sky images.

LONG EXPOSURE NOISE REDUCTION

With all cameras a setting called Long Exposure Noise Reduction (LENR) eliminates this thermal noise by taking a “dark frame” and subtracting it in-camera to yield a raw file largely free of hot pixels, and other artifacts such as edge glows.

The LENR option on the R5 did eliminate most hot pixels, though sometimes still left, or added, a few (or they might be cosmic ray hits). LENR is needed more on warm nights, and with longer exposures at higher ISOs. So the extent of thermal noise in any camera can vary a lot from shoot to shoot, and season to season.

**This compares a long exposure of nothing (with the lens cap on), both without LENR (left) and with LENR (right), to show the extent of just the thermal noise.**

The comparison above shows just thermal noise in long exposures with and without LENR, to show its effectiveness. However, bear in mind in this demo the raw files have been boosted a lot in exposure and contrast (using DxO PhotoLab with the settings shown) to exaggerate the visibility of the noise.

Like the R6, when LENR is actively taking a dark frame, the R5’s rear screen indicates “Busy,” which is annoyingly bright at night, exactly when you would be employing LENR. To hide this display, the only option is to close the screen. Instead, the unobtrusive top LCD screen alone should be used to indicate a dark frame is in progress. It does with the Ra, though Busy also displays on its rear screen as well, which is unnecessary.

As with all mirrorless cameras, the R5 lacks the “dark frame buffer” present in Canon full frame DSLRs that allows several exposures to be taken in quick succession even with LENR on.

**Long Exposure Noise Reduction is useful when the gap in time between exposures it produces is not critical.**

With all Canon R cameras, turning on LENR forces the camera to take a dark frame after every light frame, doubling the time it takes to finish every exposure. That’s a price many photographers aren’t willing to pay, but on warm nights I find it can be essential, and a best practice, for the reward of cleaner images out of camera. I found it is certainly a good practice with the R5.

TIP: If you find hot pixels are becoming more obvious over time, try this trick: turn on the Clean Manually routine for 30 seconds to a minute. In some cameras this can remap the hot pixels so the camera can better eliminate them.

STAR QUALITY

Using LENR with the R5 did not introduce any oddities such as oddly-coloured, green or wiped-out stars. Even without LENR I saw no evidence of green stars, a flaw that plagues some Sony cameras at all times, or Nikons when using LENR.

**This is a single developed raw frame from the stack of four minute exposures used to create the final image shown at the top. It shows sharp and nicely coloured stars, with no odd green stars.**

Canons have always been known for their good star colours, and the R5 maintains the tradition. According to DPReview the R5 has a mild low-pass anti-alias filter in front of its sensor. Cameras which lack such a sensor filter do produce sharper images, but stars that occupy only one or two pixels might not de-Bayer properly into the correct colours. I did not find that an issue with the R5.

As in the R6, I also saw no evidence of “star-eating,” a flaw Nikons and Sonys have been accused of over the years, due to aggressive in-camera noise reduction even on raw files. Canons have largely escaped charges of star-eating.

RED SENSITIVITY

The R5 I bought was a stock “off-the-shelf” model. It is Canon’s now-discontinued EOS Ra that was “filter-modified” to record a greater level of the deep-red wavelength from red nebulas in the Milky Way. As I show below, compared to the Ra, the R5 did well, but could not record the depth of nebulosity the Ra can, to be expected for a stock camera.

However, bright nebulas will still be good targets for the R5. But if it’s faint nebulosity you are after, both in wide-field Milky Way images and telescopic close-ups, consider getting an R5 “spectrum modified” by a third-party supplier. Or modifying an EOS R.

**This compares identically processed four-minute exposures at ISO 800 with the R5 vs. the red-sensitive Ra.**

EDGE ARTIFACTS and EDGE GLOWS

DSLRs are prone to vignetting along the top and bottom of the frame from shadowing by the upraised mirror and mirror box. Not having a mirror, and a sensor not deeply recessed in the body, largely eliminates this edge vignetting in mirrorless cameras.

While the Ra shows a very slight vignetting along the bottom of the frame (visible in the example above), the R5 was clean and fully illuminated to the edges, as it should be.

I was also pleased to see the R5 did not exhibit any annoying “amp glows” — dim, often magenta glows at the edge of the frame in long exposures, created by heat emitted from sensor electronics adding infrared (IR) glows to the image.

I saw noticeable amp glows in the Canon R6 which could only be eliminated by taking LENR dark frames. It’s a flaw that has yet to be eliminated with firmware updates. Taking LENR darks is not required with the R5, except to reduce thermal hot pixels as noted above.

With a lack of IR amp glows, the R5 should work well when filter-modified to record either more visible Hydrogen-alpha red light, or deeper into the infrared spectrum.

Resolution — Nightscapes

Now we come to the very reason to get an R5, its high resolution. Is the difference visible in typical astrophotos? In a word, yes. If you look closely.

If people only see your photos on Facebook or Instagram, no one will ever see any improvement in your images! But if your photos are seen as large prints, or you are simply a stickler for detail, then you will be happy with the R5’s 45 megapixels. (Indeed, you might wish to wait for the rumoured even higher megapixel Canon 5S!)

Nightscapes, and indeed all landscape photos by day or by night, is where you will see the benefit of more megapixels. Finer details in the foreground show up better. Images are less pixelated. In test images with all three cameras, the R5 did provide sharper images to be sure. But you do have to zoom in a lot to appreciate the improvement.

Resolution — lunar imaging

**This compares blow-ups of images of the Moon taken through a 5-inch f/6 refractor (780mm focal length) with the R6 and R5.**

The Moon through a telescope is another good test of resolution. The above comparison shows how the R5’s smaller 4.4-micron pixels do provide much sharper details and less pixelation than the R6.

Of course, one could shoot at an even longer focal length to increase the “plate scale” with the R6. But at that same longer focal length the R5 will still provide better resolution, up to the point where its pixels are sampling more than what the atmospheric seeing conditions permit to be resolved. For lunar and planetary imaging, smaller pixels are always preferred, as they allow you to reach the seeing limit with shorter and often faster optical systems.

Resolution — deep sky

**This compares extreme blow-ups of images of the North America Nebula used for the other tests, shot with a 94mm f/4.5 refractor with the three cameras.**

On starfields, the difference is not so marked. As I showed in my review of the R6, with “only” 20 megapixels the R6 can still provide detailed deep-sky images.

However, in comparing the three cameras above, with images taken at a focal length of 420mm, the R5 does provide sharper stars, with faint stars better recorded, and with less blockiness (i.e. “square stars”) on all the star images. At that focal length the plate scale with the R5 is 2.1 arc seconds per pixel. With the R6 it is 3.2 arc seconds per pixel.

This is dim green Comet PanSTARRS C/2017 K2, at top, passing above the star clusters IC 4756 at lower left and NGC 6633 at lower right on May 25-26, 2022. This is a stack of ten 5-minute exposures with a William Optics RedCat 51 at f/4.9 and the Canon R5 at ISO 800.

The R5 is a good choice for shooting open and globular star clusters, or any small targets such as planetary nebulas, especially with shorter focal length telescopes. Bright targets will allow using lower ISOs, mitigating any of the R5’s extra noise.

With an 800mm focal length telescope, the plate scale with the R5 will be 1.1 arc seconds per pixel, about the limit most seeing conditions will permit resolving. With even longer focal length telescopes, the R5’s small pixels would be oversampling the image, with little gain in resolution, at least for deep-sky subjects. Lunar and planetary imaging can benefit from plate scales of 0.5 arc seconds per pixel or smaller.

CAN YOU CreatE resolution?

**This compares an original R6 image with the same image rescaled 200% in ON1 Resize AI and Topaz Gigapixel AI, and with those three compared to an original R5 image.**

Now, one can argue that today’s AI-driven scaling programs such as ON1 Resize AI and Topaz Gigapixel AI can do a remarkable job up-sizing images while enhancing and sharpening details. Why buy a higher-megapixel camera when you can just sharpen images from a lower-resolution model?

While these AI programs can work wonders on regular images, I’ve found their machine-learning seems to know little about stars, and can often create unwanted artifacts.

In scaling up an R6 image by 200%, ON1 Resize AI 2022 made a mess of the stars and sky background. Topaz Gigapixel AI did a much better job, leaving few artifacts. But using it to double the R6 image in pixel count still produced an image that does not look as sharp as an original R5 image, despite the latter having fewer pixels than the upsized R6 image.

Yes, we are definitely pixel-peeping! But I think this shows that it is better to have the pixels to begin with in the camera, and to not depend on software to generate sharpness and detail.

VIDEO Resolution

The R5’s 45-megapixel sensor also makes possible its headline selling point when it was released in 2020: 8K movie recording, with movies sized 8192 x 4320 (DCI standard) or 7680 x 4320 (UHD standard) at 29.97 frames per second, almost IMAX quality.

Where the R6’s major selling point for me was its low-light video capability, the R5’s 8K video prowess was less important. Or so I thought. With testing, I can see it will have its place in astrophotography, especially solar eclipses.

The R5 offers the options of 8K and 4K movies each in either the wider DCI Digital Cinema standard (8K-D and 4K-D) or more common Ultra-High Definition standard (8K-U and 4K-U), as well as conventional 1080 HD.

**This shows the Moon shot with the same 460mm-focal length telescope, with full-width frame grabs from movies shot in 8K, 4K, and 4K Movie Crop modes.**

Unlike the original Canon R and Rp, the R5 and R6 can shoot 4K movies sampled from the full width of their sensors, so there is no crop factor in the field of view recorded with any lens.

However, like the R6, the R5 also offers the option of a Movie Crop mode which samples a 4K movie from the central 4096 (4K-D) or 3840 (4K-U) pixels of the sensor. As I show above, this provides a “zoomed-in” image with no loss of resolution, useful when wide field of view is not so important as is zooming into small targets, such as for lunar and solar movies.

**This compares close-ups of frame grabs of the Moon movies shown in full-frame above, as well as a frame from an R6 movie, to compare resolutions.**

So what format produces the best resolution when shooting movies? As I show above, magnified frame grabs of the Moon demonstrate that shooting at 8K provides a much less pixelated and sharper result than either the 4K-Fine HQ (which creates a “High-Quality” 4K movie downsampled from 8K) or a standard 4K movie.

Shooting a 4K movie with the R6 also produced a similar result to the 4K movies from the R5. The slightly softer image in the R5’s 4K frame can, I think, be attributed more to atmospheric seeing.

Solar eclipse use

Shooting the highest resolution movies of the Moon will be of prime interest to astrophotographers when the Moon happens to be passing in front of the Sun!

That will happen along a narrow path that crosses North America on April 8, 2024. Capturing the rare total eclipse of the Sun in 8K video will be a goal of many. At the last total solar eclipse in North America, on August 21, 2017, I was able to shoot it in 4K by using a then state-of-the-art top-end Canon DSLR loaned to me by an IMAX movie production company!

And who knows, by 2024 we might have 100-megapixel cameras capable of shooting and recording the firehose of data from 12K video! But for now, even 8K can be a challenge.

**This compares the R5 at 8K with it in the best quality 4K Fine HQ vs. the R5 and R6 in their 4K Movie Crop modes.**

However, do you need to shoot 8K to get sharp Moon, Sun or eclipse movies? The above shows the 8K frame-grab compared to the R5’s best quality full-frame 4K Fine, and the R5’s and R6’s 4K Movie Crop mode that doesn’t resample or bin pixels from the larger sensor to create a 4K movie. The Cropped movies look only slightly softer than the R5 at 8K, with less pixelation than the 4K Fine HQ movie.

When shooting the Sun or Moon through a telescope or long telephoto lens, the wide field of a full-frame movie might not be required, even to take in the two- or three-degree-wide solar corona around the eclipsed Sun.

However, if a wide field for the maximum extent of the outer corona, combined with sharp resolution is the goal, then a camera like the Canon R5 capable of shooting 8K movies will be the ticket.

And 8K will be ideal for wide-angle movies of the passage of the Moon’s shadow during any eclipse, or for moderate fields showing the eclipsed Sun flanked by Jupiter and Venus on April 8, 2024.

Canon CLOG3

Like the R6, the R5 offers the option of shooting movies in Canon’s C-Log3 profile, which records internally in 10-bit, preserving more dynamic range in movies, up to 12 stops. The resulting movie looks flat, but when “colour graded” later in post, the movie records much more dynamic range, as I show above. Without C-Log3, the bright sunlit lunar crescent is blown out, as will be the Sun’s inner corona.

The bright crescent Moon with dim Earthshine is a good practice-run stand-in for the eclipsed Sun with its wide range of brightness from the inner to the outer corona.

Sample Moon Movies

For the full comparison of the R5 and R6 in my test shoot of the crescent Moon, see this narrated demo movie on Vimeo for the 4K movies, shot in various modes, both full-frame and cropped, with C-Log3 on and off.

Keep in mind that video compression in the on-line version may make it hard to see the resolution difference between shooting modes.

A “private link” 10-minute video on Vimeo demonstrating 4K video clips with the R5 and R6.

For a movie of the 8K footage, though downsized to 4K for the Vimeo version (the full sized 8K file was 29 Gigs!), see this sample movie below on Vimeo.

A “private link” video on Vimeo demonstrating 8K video clips with the R5.

LOw-Light VIDEO

Like the R6, the R5 can shoot at a dragged shutter speed as slow as 1/8-second. That slow shutter, combined with a fast f/1.4 to f/2 lens, and ISOs as high as 51,200 are the keys to shooting movies of the night sky.

Especially auroras. Only when auroras get shadow-casting bright can we shoot at the normal 1/30-second shutter speed of movies and at lower ISOs.

**This compares frame grabs of aurora movies shot the same night with the R5 at 8K and 4K with the Canon R6 at 4K, all at ISO 51,200.**

I was able to shoot a decent aurora one night from home with both the R5 and R6, and with the same fast TTArtisan 21mm f/1.5 RF lens. The sky and aurora changed in brightness from the time I shot with the R6 first to the R5 later. But even so, the movies serve as a look at how the two cameras perform for real-time aurora movies.

Auroras are where we need to shoot full-frame, for the maximum field of view, and at high ISOs. The R5’s maximum ISO is 51,200, while the R6 goes up to 204,800, though it is largely unusable at that speed for actual shooting, just for previewing scenes.

As expected, the R6 was much less noisy than the R5, by about two stops. The R5 is barely usable at ISO 51,200, while the R6 works respectably well at that speed. If auroras get very bright, then slower ISOs can be used, making the R5 a possible camera for low-light use, but it would not be a first choice, unless 8K auroras are a must-have.

Sample aurora Movies

For a narrated movie comparing the R5 and R6 at 4K on the aurora, stepping both through a range of ISO speeds, see this movie at Vimeo.

A “private link” video on Vimeo demonstrating 4K aurora clips with the R5 and R6.

For a movie showing the same aurora shot with the R5 at 8K, see this movie. However, it has been down-sized to 4K for on-line viewing, so you’ll see little difference between it and the 4K footage. Shooting at 8K did not improve or smooth noise performance.

A “private link” video on Vimeo demonstrating 8K aurora clips with the R5.

BATTERY LIFE — Stills and video

Canon’s new LP-E6NH battery supports charging through the USB-C port and has a higher 2130mAh capacity than the 1800mAh LP-E6 batteries. However, the R5 is compatible with the older batteries.

**Like the R6, the R5 comes with a new version of Canon’s standard LP-E6 battery, the LP-E6NH.**

On mild nights, I found the R5 ran fine on one battery for the 3 to 4 hours needed to shoot a time-lapse sequence, or set of deep-sky images, with power to spare. Now, that was with the camera in “Airplane Mode,” which I always use regardless, to turn off the power-consuming WiFi and Bluetooth, which I never use on cameras.

As I noted with the R6, for demanding applications, especially in winter, the R5 can be powered by an outboard USB power bank that has Power Delivery or “PD” capability.

The exception for battery use is when shooting videos, especially 8K. That can drain a battery after an hour of recording, though it takes only 10 to 12 minutes of 8K footage to fill a 128 gigabyte card. While less than half that length will be needed to capture any upcoming total eclipse from diamond ring to diamond ring, the result is still a massive file.

OVERHEATING

More critically, the R5 is also infamous for overheating and shutting down when shooting 8K movies, after a time that depends on how hot the environment is. I found the R5 shot 8K or 4K Fine HQ for about 22 minutes at room temperature before the overheat warning first came on, then shut off recording two or three minutes later. Movie recording cannot continue until the R5 cools off sufficiently, which takes at least 10 to 15 minutes.

That deficiency might befoul unwary eclipse photographers in 2024. The answer for “no-worry” 8K video recording is the Canon R5C, the video-centric version of the R5, with a built-in cooling fan.

Features and usability

While certainly not designed with astrophotography in mind, the R5 has several hardware and firmware features that are astrophoto friendly.

Like all Canon cameras made in the last few years, the R5 has Canon’s standard articulated screen, which can be angled up for convenient viewing when on a telescope. It is also a full touch screen, with all important camera settings and menus adjustable on screen, good for use at night.

With 2.1 million dots, the R5’s rear screen has a higher resolution than the 1.62-million-dot screen of the R6, and much higher than the 1 million pixels of the Rp’s screen, but is the same resolution as in the R and Ra.

**The R5’s top-mounted backlit LCD screen**

The R5, like the original R, has a top backlit LCD screen for display of current camera settings, battery level and Bulb timer. The lack of a top screen was one of my criticisms of the R6.

Yes, the hardware Mode dial of the R6 and Rp does make it easier to switch shooting modes, such as quickly changing from Stills to Movie. However, for astrophotography the top screen provides useful information during long exposures, and is handy to check when the camera is on a telescope or tripod aimed up to the sky, without spoiling dark adaptation. I prefer to have one.

**The R5’s front-mounted N3-style remote port**

The R5’s remote shutter port, used for connecting external intervalometers or time-lapse motion controllers, is Canon’s professional-grade three-pronged N3 connector. It’s sturdier than the 2.5mm mini-phono plug used by the Rp, R and R6. It’s a plus for the R5.

As with all new cameras, the R5’s USB port is a USB-C type. A USB-C cable is included.

**The R5’s back panel buttons and controls**

Like the R6, the R5 has a dedicated magnification button on the back panel for zooming in when manually focusing or inspecting images. In the R and Ra, that button is only on the touch panel rear screen, where it has to be called up by paging to that screen, an inconvenience. While virtual buttons on a screen are easier to see and operate at night than physical buttons, I find a real Zoom button handy as it’s always there.

**The R5’s twin cards, a CFexpress Type B and an SD UHS-II**

To handle the high data rates of 8K video and also 4K video when set to the high frame rate option of 120 fps, one of the R5’s memory card slots requires a CFexpress Type B card, a very fast but more costly format.

As I had no card reader for this format, I had to download movies via a USB cable directly from the camera to my computer, using Canon’s EOS Utility software, as Adobe Downloader out of Adobe Bridge refused to do the job. Plan to buy a card reader.

In the menus, you can choose to record video only to the CFexpress, and stills only to the SD card, or both stills and movies to each card for a backup, with the limitation that 8K and 4K 120fps won’t record to the SD card, even very fast ones.

FIRMWARE FEATURES

Unlike the Canon R and Ra (which both annoyingly lack a built-in intervalometer), but like the R6, the R5 has an Interval Timer in its firmware. This can be used to set up a time-lapse sequence, but with exposures only up to the maximum of 30 seconds allowed by the camera’s shutter speed settings, true of most in-camera intervalometers. Even so, this is a useful function for simple time-lapses.

As with most recent Canon DSLRs and DSLMs, the R5 also includes a built-in Bulb Timer. This allows setting an exposure of any length (many minutes or hours) when the camera is in Bulb mode. However, it cannot be combined with the Interval Timer for multiple exposures; it is good only for single shots. Nevertheless, I find it useful for shooting long exposures for the ground component of nightscape scenes.

While Canon cameras don’t have Custom Function buttons per se (unlike Sonys), the R5’s various buttons and dials can be custom programmed to functions other than their default assignments. I assign the * button to turning on and off the Focus Peaking display and, as shown, the AF Point button to a feature only available as a custom function, one that temporarily brightens the rear screen to full, good for quickly checking framing at night.

**Assigning Audio Memos to the Rate button**

A handy feature of the R5 is the ability to add an audio notation to images. You shoot the image, play it back, then use the Rate button (if so assigned) to record a voice memo of up to 30 seconds, handy for making notes in the field about an image or a shoot. The audio notes are saved as WAV files with the same file number as the image.

**The infamous Release Shutter Without Lens command**

Like other EOS R cameras, the R5 has this notorious “feature” that trips up every new user who attaches their Canon camera to a telescope or manual lens, only to find the shutter suddenly doesn’t work. The answer is to turn ON “Release Shutter w/o Lens” found buried under Custom Functions Menu 4. Problem solved!

OTHER FEATURES

I provide more details of other features and settings of the R5, many of which are common to the R6, in my review of the R6 here.

**Multi-segment panoramas with the R5, like this aurora scene, yield superb resolution but can become massive in size, pressing the ability of software and hardware to process them.**

CONCLUSION

No question, the Canon R5 is costly. Most buyers would need to have very good daytime uses to justify its purchase, with astrophotography a secondary purpose.

That said, other than low-light night sky videos, the R5 does work very well for all forms of astrophotography, providing a level of resolution that lesser cameras simply cannot.

Nevertheless, if it is just deep-sky imaging that is of interest, then you might be better served with a dedicated cooled-sensor CMOS camera, such as one of the popular ZWO models, and the various accessories that need to accompany such a camera.

But for me, when it came time to buy another premium camera, I still preferred to have a model that could be used easily, without computers, for many types of astro-images, particularly nightscapes, tracked wide-angle starfields, as well as telescopic images.

Since buying the R5, after first suspecting it would prove too noisy to be practical, it has in fact become my most used camera, at least for all images where the enhanced red sensitivity of the EOS Ra is not required. But for low-light night videos, the R6 is the winner.

However, to make use of the R5’s resolution, you do have to match it with sharp, high-quality lenses and telescope optics, and have the computing power to handle its large files, especially when stitching or stacking lots of them. The R5 can be just the start of a costly spending spree!

September 23, 2021November 3, 2022

Testing the Canon R6 for Astrophotography

In an extensive technical blog, I put the Canon R6 mirrorless camera through its paces for the demands of astrophotography.

Every major camera manufacturer, with the lone exception of stalwart Pentax, has moved from producing digital lens reflex (DSLR) cameras, to digital single lens mirrorless (DSLM) cameras. The reflex mirror is gone, allowing for a more compact camera, better movie capabilities, and enhanced auto-focus functions, among other benefits.

But what about for astrophotography? I reviewed the Sony a7III and Nikon Z6 mirrorless cameras here on my blog and, except for a couple of points, found them excellent for the demands of most astrophotography.

For the last two years I’ve primarily used Canon’s astro-friendly and red-sensitive EOS Ra mirrorless, a model sadly discontinued in September 2021 after just two years on the market. I reviewed that camera in the April 2020 issue of Sky & Telescope magazine, with a quick first look here on my blog.

The superb performance of the Ra has prompted me to stay with the Canon mirrorless R system for future camera purchases. Here I test the mid-priced R6, introduced in August 2020.

NOTE: In early November 2022 Canon announced the EOS R6 MkII, which one assumes will eventually replace the original R6 once stock of that camera runs out. The MkII has a 24 Mp sensor for slightly better resolution, and offers longer battery life. But the main improvements over the R6 is to autofocus accuracy, a function of little use to astrophotographers. Only real-world testing will tell if the R6 MkII has better or worse noise levels than the R6, or has eliminated the R6’s amp glow, reported on below.

M31, the spiral galaxy in Andromeda, with the Canon R6 mirrorless camera. It is a stack of 8 x 8-minute exposures at ISO 800, blended with a stack of 8 x 2-minute exposures at ISO 400 for the core, to prevent it from overexposing too much, all with a SharpStar 76mm apo refractor at f/4.5 with its field flattener/reducer.

TL;DR SUMMARY

The Canon R6 has proven excellent for astrophotography, exhibiting better dynamic range and shadow recovery than most Canon DSLRs, due to the ISO invariant design of the R6 sensor. It is on par with the low-light performance of Nikon and Sony mirrorless cameras.

The preview image is sensitive enough to allow easy framing and focusing at night. The movie mode produces usable quality up to ISO 51,200, making 4K movies of auroras possible. Canon DSLRs cannot do this.

Marring the superb performance are annoying deficiencies in the design, and one flaw in the image quality – an amp glow – that particularly impacts deep-sky imaging.

R6 pros

The Canon R6 is superb for its:

Low noise, though not exceptionally so
ISO invariant sensor performance for good shadow recovery
Sensitive live view display with ultra-high ISO boost in Movie mode
Relatively low noise Movie mode with full frame 4K video
Low light auto focus and accurate manual focus assist
Good battery life

R6 cons

The Canon R6 is not so superb for its:

Design Deficiencies

Lack of a top LCD screen
Bright timer display in Bulb on the rear screen
No battery level indication when shooting
Low grade R3-style remote jack, same as on entry-level Canon DSLRs

Image Quality Flaw

Magenta edge “amp glow” in long exposures

The Canon Ra on the left with the 28-70mm f/2 RF lens and the **Canon R6** on the right with the 70-200mm f/2/8 RF lens, two superb but costly zooms for the R system cameras.

CHOOSING THE R6

Canon’s first full-frame mirrorless camera, the 30-megapixel EOS R, was introduced in late 2018 to compete with Sony. As of late-2021 the main choices in a Canon DSLM for astrophotography are either the original R, the 20-megapixel R6, the 26-megapixel Rp, or the 45-megapixel R5.

The new 24-megapixel Canon R3, while it has impressive low-noise performance, is designed primarily for high-speed sports and news photography. It is difficult to justify its $6,000 cost for astro work.

I have not tested Canon’s entry-level, but full-frame Rp. While the Rp’s image quality is likely quite good, its small battery and short lifetime on a single charge will be limiting factors for astrophotography.

Nor have I tested the higher-end R5. Friends who use the R5 for nightscape work love it, but with smaller pixels the R5 will be noisier than the R6, which lab tests at sites such as DPReview.com seem to confirm.

Meanwhile, the original EOS R, while having excellent image quality and features, is surely destined for replacement in the near future – with a Canon EOS R Mark II? The R’s successor might be a great astrophoto camera, but with the Ra gone, I feel the R6 is currently the prime choice from Canon, especially for nightscapes.

I tested an R6 purchased in June 2021 and updated in August with firmware v1.4. I’ll go through its performance and functions with astrophotography in mind. I’ve ignored praised R6 features such as eye tracking autofocus, in-body image stabilization, and high speed burst rates. They are of limited or no value for astrophotography.

Along the way, I also offer a selection of user tips, some of which are applicable to other cameras.

LIVE VIEW FOCUSING AND FRAMING

**“Back-of-the-camera” views** of the R6 in its normal Live View mode (upper left) and its highly-sensitive Movie Mode (upper right), compared to views with four other cameras. Note the Milky Way visible with the R6 in its Movie mode, similar to the Sony in Bright Monitoring mode.

The first difference you will see when using any new mirrorless camera, compared to even a high-end DSLR, is how much brighter the “Live View” image is when shooting at night. DSLM cameras are always in Live View – even the eye-level viewfinder presents a digital image supplied by the sensor.

As such, whether on the rear screen on in the viewfinder, you see an image that closely matches the photo you are about to take, because it is the image you are about to take.

To a limit. DSLMs can do only so much to simulate what a long 30-second exposure will look like. But the R6, like many DSLMs, goes a long way in providing a preview image bright enough to frame a dark scene and focus on bright stars. Turn on Exposure Simulation to brighten the live image, and open the lens as wide as possible.

The Canon R6 in its **Movie Mode** at ISO 204,800 and with a lens wide open.

But the R6 has a trick up its sleeve for framing nightscapes. Switch the Mode dial to Movie, and set the ISO up to 204,800 (or at night just dial in Auto ISO), and with the lens wide open and shutter on 1/8 second (as above), the preview image will brighten enough to show the Milky Way and dark foreground, albeit in a noisy image. But it’s just for aiming and framing.

This is similar to the excellent, but well-hidden Bright Monitoring mode on Sony Alphas. This high-ISO Movie mode makes it a pleasure using the R6 for nightscapes. The EOS R and Ra do not have this ability. While their live view screens are good, they are not as sensitive as the R6’s, with the R and Ra’s Movie modes able to go up to only ISO 12,800. The R5 can go up to “only” ISO 51,200 in its Movie mode, good but not quite high enough for live framing on dark nights.

**Comparing Manual vs. Auto Focus** results with the R6.

The R6 will also autofocus down to a claimed EV -6.5, allowing it to focus in dim light for nightscapes, a feat impossible in most cameras. In practice with the Canon RF 15-35mm lens at f/2.8, I found the R6 can’t autofocus on the actual dark landscape, but it can autofocus on bright stars and planets (provided, of course, the camera is fitted with an autofocus lens).

Autofocusing on bright stars proved very accurate. By comparison, while the Ra can autofocus on distant bright lights, it fails on bright stars or planets.

Turning on Focus Peaking makes stars turn red, yellow or blue (your choice of colours) when they are in focus, as a reassuring confirmation.

The **Focus Peaking and Focus Guide** menu.

The R6 live view display with Focus Guide arrows on and focused on a star, Antares.

In manual focus, an additional Focus Aid overlay provides arrows that close up and turn green when in focus on a bright star or planet. Or you can zoom in by 5x or 10x to focus by eye the old way by examining the star image. I wish the R6 had a 15x or 20x magnification; 5x and 10x have long been the Canon standards. Only the Ra offered 30x for ultra-precise focusing on stars.

In all, the ease of framing and focusing will be the major improvement you’ll enjoy by moving to any mirrorless, especially if your old camera is a cropped-frame Canon Rebel or T3i! But the R6 particularly excels at ease of focusing and framing.

NOISE PERFORMANCE

The key camera characteristic for astrophoto use is noise. I feel it is more important than resolution. There’s little point in having lots of fine detail if it is lost in a blizzard of high-ISO noise. And for astro work, we are almost always shooting at high ISOs.

**Comparing the R6’s noise** at increasingly higher ISO speeds on a starlit nightscape.

With just 20 megapixels, low by today’s standards, the R6 has individual pixels, or more correctly “photosites,” that are each 6.6 microns in size, the “pixel pitch.”

By comparison, the 30-megapixel R (and Ra) has a pixel pitch of 5.4 microns, the 45-megapixel R5’s pixel pitch is 4.4 microns, while the acclaimed low-light champion in the camera world, the 12-megapixel Sony a7sIII, has large 8.5-micron photosites.

Each generation of camera also improves the signal-to-noise ratio by suppressing noise via its sensor design and improved signal processing hardware and firmware. The R6 uses Canon’s latest DIGIC X processor shared by the company’s other mirrorless cameras.

**Comparing the R6** **noise** with the 6D MkII and EOS Ra on a deep-sky subject, galaxies.

In noise tests comparing the R6 against the Ra and Canon 6D Mark II, all three cameras showed a similar level of noise at ISO settings from 400 up to 12,800. But the 6D Mark II performed well only when properly exposed. Both the R6 and Ra performed much better for shadow recovery in underexposed scenes.

**Comparing the R6** **noise** with with the 6D MkII and EOS Ra on a shadowed nightscape.

**Comparing the R6 noise** with the EOS Ra on the Andromeda Galaxy at typical deep-sky ISO speeds.

In nightscapes and deep-sky images the R6 and Ra looked nearly identical at each of their ISO settings. This was surprising considering the Ra’s smaller photosites, which perhaps attests to the low noise of the astronomical “a” model.

Or it could be that the R6 isn’t as low noise as it should be for a 20 megapixel camera. But it is as good as it gets for Canon cameras, and that’s very good indeed.

I saw no “magic ISO” setting where the R6 performed better than at other settings. Noise increased in proportion to the ISO speed. It proved perfectly usable up to ISO 6400, with ISO 12,800 acceptable for stills when necessary.

ISO INVARIANCY

The flaw in many Canon DSLRs, one documented in my 2017 review of the 6D Mark II, was their poor dynamic range due to the lack of an ISO invariant sensor design.

The R6, as with Canon’s other R-series cameras, has largely addressed this weakness. The sensor in the R6 appears to be nicely ISO invariant and performs as well as the Sony and Nikon cameras I have used and tested, models praised for their ISO invariant behaviour.

Where this trait shows itself to advantage is on nightscapes where the starlit foreground is often dark and underexposed. Bringing out detail in the shadows in raw files requires a lot of Shadow Recovery or increasing the Exposure slider. Images from an ISO invariant sensor can withstand the brightening “in post” far better, with minimal noise increase or degradations such as a loss of contrast, added banding, or horrible discolourations.

**Comparing the R6 for ISO Invariancy** on a starlit nightscape.

To test the R6, I shot sets of images at the same shutter speed, one well-exposed at a high ISO, then several at successively lower ISOs to underexpose by 1 to 5 stops. I then brightened the underexposed images by increasing the Exposure in Camera Raw by the same 1 to 5 stops. In an ideal ISO invariant sensor, all the images should look the same.

The R6 did very well in images underexposed by up to 4 stops. Images underexposed by 5 stops started to fall apart, but I’ve seen that in Sony and Nikon images as well.

**Comparing the R6 for ISO Invariancy** on a moonlit nightscape.

This behaviour applies to images underexposed by using lower ISOs than what a “normal” exposure might require. Underexposing with lower ISOs can help maintain dynamic range and avoid highlight clipping. But with nightscapes, foregrounds can often be too dark even when shot at an ISO high enough to be suitable for the sky. Foregrounds are almost always underexposed, so good shadow recovery is essential for nightscapes, and especially time-lapses, when blending in separate longer exposures for the ground is not practical.

With its improved ISO invariant sensor, the R6 will be a fine camera for nightscape and time-lapse use, which was not true of the 6D Mark II.

For those interested in more technical tests and charts, I refer you to DxOMark’s report on the Canon R6.

**Comparing R6 images underexposed** in 1-stop increments by using shorter shutter speeds.

**Comparing R6 images underexposed** in 1-stop increments by using smaller apertures.

However, to be clear, ISO invariant behaviour doesn’t help you as much if you underexpose by using too short a shutter speed or too small a lens aperture. I tested the R6 in series of images underexposed by keeping ISO the same but decreasing the shutter speed then the aperture in one-stop increments.

The underexposed images fell apart in quality much sooner, when underexposed more than 3 stops. Again, this is behaviour similar to what I’ve seen in Sonys and Nikons. For the best image quality I feel it is always a best practice to expose well at the camera. Don’t count on saving images in post.

An in-camera image fairly well exposed with an **ETTR histogram.**

TIP: Underexposing by using too short an exposure time is the major mistake astrophotographers make, who then wonder why their images are riddled with odd artifacts and patten noise. Always Expose to the Right (ETTR), even with ISO invariant cameras. The best way to avoid noise is to give your sensor more signal, by using longer exposures or wider apertures. Use settings that push the histogram to the right.

LONG EXPOSURE NOISE REDUCTION

All cameras will exhibit thermal noise in long exposures, especially on warm nights. This form of noise peppers the shadows with hot pixels, often brightly coloured.

This is not the same as the shot and read noise that adds graininess to high-ISO images and that noise reduction software can smooth out. This is a common misunderstanding, even among professional photographers who should know better!

Thermal noise is more insidious and harder to eliminate in post without harming the image. However, Monika Deviat offers a clever method here at her website.

Long Exposure Noise Reduction (LENR) eliminates this thermal noise by taking a “dark frame” and subtracting it in-camera to yield a raw file free of hot pixels.

And yes, LENR does apply to raw files, another fact even many professional photographers don’t realize. It is High ISO Noise Reduction that applies only to JPGs, along with Color Space and Picture Styles.

Comparing a dark nightscape without and with LENR on a warm night. Hot pixels are mostly gone at right.

The LENR option on the R6 did eliminate most hot pixels, though sometimes still left, or added, a few. LENR is needed more on warm nights, and with longer exposures at higher ISOs. So the extent of thermal noise in any camera can vary a lot from shoot to shoot.

When LENR is active, the R6’s rear screen lights up with “Busy,” which is annoyingly bright. To hide this display, the only option is to close the screen.

As with the EOS Ra, and all mirrorless cameras, the R6 has no “dark frame buffer” that allows several exposures to be taken in quick succession even with LENR on. Canon’s full-frame DSLRs have this little-known buffer that allows 3, 4, or 5 “light frames” to be taken in a row before the LENR dark frame kicks in a locks up the camera on Busy.

**Comparing long exposure images** with the lens cap on (**dark frames**), to show just thermal noise. The right edge of the frame is shown, blown up, to reveal the amp glow, which LENR removes.

With all Canon R cameras, and most other DSLRs, turning on LENR forces the camera to take a dark frame after every light frame, doubling the time it takes to finish every exposure. That’s a price many photographers aren’t willing to pay, but on warm nights it can be necessary, and a best practice, for the reward of cleaner images.

The standard Canon **Sensor Cleaning** menu.

STAR QUALITY

Using LENR with the R6 did not introduce any oddities such as oddly-coloured, green or wiped-out stars. Even without LENR I saw no evidence of green stars, a flaw that plagues some Sony cameras at all times, or Nikons when using LENR.

**Comparing the R6 for noise and star colours** at typical deep-sky ISOs and exposure times.

Canons have always been known for their good star colours, and the R6 is no exception. According to DPReview the R6 has a low-pass anti-alias filter in front of its sensor. Cameras which lack such a sensor filter do produce sharper images, but stars that occupy only one or two pixels might not de-Bayer properly into the correct colours. That’s not an issue with the R6.

I also saw no “star-eating,” a flaw Nikons and Sonys have been accused of over the years, due to aggressive in-camera noise reduction even on raw files. Canons have always escaped charges of star-eating.

VIGNETTING/SHADOWING

This illustrates the lack of edge shadows but magenta edge glows in a single Raw file boosted for contrast.

That is certainly true of the R6. Images boosted a lot in contrast, as we do with deep-sky photos, show not the slightest trace of vignetting along the top or bottom edges There were no odd clips or metal bits intruding into the light path, unlike in the Sony a7III I tested in 2018.

The full frame of the R6 can be used without need for cropping or ad hoc edge brightening in post. Except …

EDGE ARTIFACTS/AMP GLOWS

The R6 did exhibit one serious and annoying flaw in long-exposure high-ISO images – a magenta glow along the edges, especially the right edge and lower right corner.

**Comparing a close-up of a nightscape**, without and with LENR, to show the edge glow gone with LENR on.

Whether this is the true cause or not, it looks like “amplifier glow,” an effect caused by heat from circuitry illuminating the sensor with infra-red light. It shows itself when images are boosted in contrast and brightness in processing. It’s the sort of flaw revealed only when testing for the demands of astrophotography. It was present in images I took through a telescope, so it is not IR leakage from an auto-focus lens.

I saw this type of amp glow with the Sony a7III, a flaw eventually eliminated in a firmware update that, I presume, turned off unneeded electronics in long exposures.

Amp glow is something I have not seen in Canon cameras for many years. In a premium camera like the R6 it should not be there. Period. Canon needs to fix this with a firmware update.

UPDATE AUGUST 1, 2022: As of v1.6 of the R6 firmware, released in July 2022, the amp glow issue remains and has not been fixed. It may never be at this point.

It is the R6’s only serious image flaw, but it’s surprising to see it at all. Turning on LENR eliminates the amp glow, as it should, but using LENR is not always practical, such as in time-lapses and star trails.

For deep-sky photography high-ISO images are pushed to extremes of contrast, revealing any non-uniform illumination or colour. The usual practice of taking and applying calibration dark frames should also eliminate the amp glow. But I’d rather it not be there in the first place!

RED SENSITIVITY

The R6 I bought was a stock “off-the-shelf” model. It is Canon’s now-discontinued EOS Ra model that is (or was) “filter-modified” to record a greater level of the deep red wavelength from red nebulas in the Milky Way. Compared to the Ra, the R6 did well, but could not record the depth of nebulosity the Ra can, to be expected for a stock camera.

**Comparing the stock R6 with the filter-modified Ra** on Cygnus nebulosity.

In wide-field images of the Milky Way, the R6 picked up a respectable level of red nebulosity, especially when shooting through a broadband light pollution reduction filter, and with careful processing.

**Comparing the stock R6 with the filter-modified Ra** on the Swan Nebula with a telescope with minimal processing to the Raw images.

**Comparing the stock R6 with the filter-modified Ra** on the Swan Nebula with a telescope with a dual narrowband filter and with colour correction applied to the single Raw images.

However, when going after faint nebulas through a telescope, even the use of a narrowband filter did not help bring out the target. Indeed, attempting to correct the extreme colour shift introduced by such a filter resulted in a muddy mess and accentuated edge glows with the R6, but worked well with the Ra.

While the R6 could be modified by a third party, the edge amp glow might spoil images, as a filter modification can make a sensor even more sensitive to IR light, potentially flooding the image with unwanted glows.

TIP: Buying a used Canon Ra (if you can find one) might be one choice for a filter-modified mirrorless camera, one much cheaper than a full frame cooled CMOS camera such as a ZWO ASI2400MC. Or Spencer’s Camera sells modified versions of all the R series cameras with a choice of sensor filters. But I have not used any of their modded cameras.

RESOLUTION

A concern of prospective buyers is whether the R6’s relatively low 20-megapixel sensor will be sharp enough for their purposes. R6 images are 5472 by 3648 pixels, much less than the 8000+ pixel-wide images from high-resolution cameras like the Canon R5, Nikon Z7II or Sony a1.

Unless you sell your astrophotos as very large prints, I’d say don’t worry. In comparisons with the 30-megapixel Ra I found it difficult to see a difference in resolution between the two cameras. Stars were nearly as well resolved in the R6, and only under the highest pixel-peeping magnification did stars look a bit more pixelated in the R6 than in the Ra. Faint stars were equally well recorded.

**Comparing resolution of the R6 vs. Ra** with a blow-up of wide-field 85mm images

**Comparing resolution of the R6 vs. Ra** on blow-ups of the Andromeda Galaxy with a 76mm apo refractor. The R6 is more pixellated but it takes pixel peeping to see it!

The difference between 20 and 30 megapixels is not as great as you might think for arc-second-per-pixel plate scale. I think it would take going to the R5 with its 45 megapixel sensor to provide enough of a difference in resolution over the R6 to be obvious in nightscape scenes, or when shooting small, detailed deep-sky subjects such as globular clusters.

If landscape or wildlife photography by day is your passion, with astrophotography a secondary purpose, then the more costly but highly regarded R5 might be the better choice.

**Super Resolution menu** in Adobe Lightroom.

TIP: Adobe now offers (in Lightroom and in Camera Raw) a Super Resolution option, that users might think (judging by the rave reviews on-line) would be the answer to adding resolution to astro images from “low-res” cameras like the R6.

**Comparing a normal R6 image** with the same image **upscaled with Super Resolution**.

Sorry! In my tests on astrophotos I’ve found Super Resolution results unsatisfactory. Yes, stars were less pixelated, but they became oddly coloured in the AI-driven up-scaling. Green stars appeared! The sky background also became mottled and uneven.

I would not count on such “smart upscaling” options to add more pixels to astro-images from the R6. Then again, I don’t think there’s a need to.

RAW vs. cRAW

Canon now offers the option of shooting either RAW or cRAW files, the latter being the same megapixel count but compressed in file size by almost a factor of two. This allows shooting twice as many images before card space runs out, perhaps useful for shooting lots of time-lapses on extended trips away from a computer.

The **R6 Image Quality** menu with the cRAW Option.

Comparing an **R6 cRAW with a RAW** image.

However, the compression is not lossless. In high-ISO test images purposely underexposed, then brightened in post, I could see a slight degradation in cRAW images – the noise background looked less uniform and exhibited a blocky look, like JPG artifacts.

TIP: With two SD card slots in the R6 (the second card can be set to record either a backup of images on card one, or serve as an overflow card) and the economy of large SD cards, there’s not the need to conserve card space as there once was. I would suggest always shooting in the full RAW format. Why accept any compression and loss of image quality?

BATTERY LIFE

The R6 uses a new version of Canon’s standard LP-E6 battery, the LP-E6NH, that supports charging through the USB-C port and has a higher 2130mAh capacity than the 1800mAh LP-E6 batteries. However, the R6 is compatible with older batteries.

On warm nights, I found the R6 ran fine on one battery for the 3 to 4 hours needed to shoot a time-lapse sequence, with power to spare. However, as noted below, the lack of a top LCD screen means there’s no ongoing display of battery level, a deficiency for time-lapse and deep-sky work.

For demanding applications, especially in winter, the R6 can be powered by an outboard USB power bank that has “Power Delivery” capability. That’s a handy feature. There’s no need to install a dummy battery leading out to a specialized power source.

The R6’s Connection menu with **Airplane mode** to turn off battery-eating WiFi and Bluetooth.

TIP: Putting the camera into Airplane mode (to turn off WiFi and Bluetooth), turning off the viewfinder, and either switching off or closing the rear screen all helps conserve power. The R6 does not have GPS built in. Tagging images with location data requires connecting to your phone.

VIDEO USE

A major selling point for me was the R6’s low-light video capability. It replaces my Sony A7III, which had been my “go to” camera for real-time 4K movies of auroras.

As best I can tell (from the dimmer auroras I’ve shot to date), the R6 performs equally as well as the Sony. It is able to record good quality (i.e. acceptably noise-free) 4K movies at ISO 25,600 to ISO 51,200. While it can shoot at up to ISO 204,800, the excessive noise makes the top ISO an emergency-use only setting.

The R6’s Movie size and quality options, with 4K and Full HD formats and frame rates.

Comparing the R6 on a dim aurora at various high ISO speeds. Narrated at the camera — excuse the wind noise! Switch to HD mode for the best video playback quality. This was shot in 4K but WordPress plays back only in HD.

The R6 can shoot at a dragged shutter speed as slow as 1/8-second – good, though not as slow as the Sony’s 1/4-second slowest shutter speed in movie mode. That 1/8-second shutter speed and a fast f/1.4 to f/2 lens are the keys to shooting movies of the night sky. Only when auroras get shadow-casting bright can we shoot at the normal 1/30-second shutter speed and at lower ISOs.

As with Nikons (but not Sonys), the Canon R6 saves its movie settings separately from its still settings. When switching to Movie mode you don’t have to re-adjust the ISO, for example, to set it higher than it might have been for stills, very handy for taking both stills and movies of an active aurora, where quick switching is often required.

Unlike the R and Rp, the R6 captures 4K movies from the full width of the sensor, preserving the field of view of wide-angle lenses. This is excellent for aurora shooting.

A 4K movie of the Moon in full-frame and copped-frame modes, narrated at the camera. Again, this was shot in 4K but WordPress plays back only in HD.

**Comparing blow-ups of frame-grabbed stills** from a full-frame 4K vs. Cropped frame 4K. The latter is less pixellated.

However, the R6 offers the option of a “Movie Crop” mode. Rather than taking the 4K movie downsampled from the entire sensor, this crop mode records from a central 1:1 sampled area of the sensor. That mode can be useful for high-magnification lunar and planetary imaging, for ensuring no loss of resolution. It worked well, producing videos with less pixelated fine details in test movies of the Moon.

Though of course I have yet to test it on one, the R6 should be excellent for movies of total solar eclipses. It can shoot 4K up to 60 frames per second in both full frame and cropped frame. It cannot shoot 6K (buy the R3!) or 8K (buy the R5!).

The R6’s Canon Log settings menu for video files.

Shooting in the R6’s Canon cLog3 profile records internally in 10-bit, preserving more dynamic range in movies, up to 12 stops. During eclipses, that will be a benefit for recording totality, with the vast range of brightness in the Sun’s corona. It should also aid in shooting auroras which can vary over a huge range in brightness.

**Grading a cLog** format movie in Final Cut under Camera LUT.

TIP: Processing cLog movies, which look flat out of camera, requires applying a cLog3 Look Up Table, or LUT, to the movie clips in editing, a step called “colour grading.” This is available from Canon, from third-party vendors or, as it was with my copy of Final Cut Pro, might be already installed in your video editing software. When shooting, turn on View Assist so the preview looks close to what the final graded movie will look like.

EXPOSURE TRACKING IN TIME-LAPSES

In one test, I shot a time-lapse from twilight to darkness with the R6 in Aperture Priority auto-exposure mode, of a fading display of noctilucent clouds. I just let the camera lengthen the shutter speed on its own. It tracked the darkening sky very well, right down to the camera’s maximum exposure time of 30 seconds, using a fish-eye lens at f/2.8. This demonstrated that the light meter in the R6 was sensitive enough to work well in dim light.

Other cameras I have used cannot do this. The meter fails at some point and the exposure stalls at 5 or 6 seconds long, resulting in most frames after that being underexposed. By contrast, the R6 showed excellent performance, negating the need for special bulb ramping intervalometers for some “holy grail” scenes. Here’s the resulting movie.

A time-lapse of 450 frames from 0.4 seconds to 30 seconds, with the R6 in Av mode. Set to 1080P for the best view!

A screenshot from LRTimelapse showing the smoothness of the exposure tracking (the blue line) through the sequence,

In addition, the R6’s exposure meter tracked the darkening sky superbly, with nary a flicker or variation. Again, few cameras can do this. Nikons have an Exposure Smoothing option in their Interval Timers which works well.

The R6 has no such option but doesn’t seem to need it. The exposure did fail at the very end, when the shutter reached its maximum of 30 seconds. If I had the camera on Auto ISO, it might have started to ramp up the ISO to compensate, a test I have yet to try. Even so, this is impressive time-lapse performance in auto-exposure.

MISSING FEATURES

The R6, like the low-end Rp, lacks a top LCD screen for display of camera settings and battery level. In its place we get a traditional Mode dial, which some daytime photographers will prefer. But for astrophotography, a backlit top LCD screen provides useful information during long exposures.

Without it, the R6 provides no indication of battery level while a shoot is in progress, for example, during a time-lapse. A top screen is also useful for checking ISO and other settings by looking down at the camera, as is usually the case when it’s on a tripod or telescope.

The lack of a top screen is an inconvenience for astrophotography. We are forced to rely on looking at the brighter rear screen for all information. It is a flip-out screen, so can be angled up for convenient viewing on a telescope.

The **R6’s flip screen**, similar to most other new Canon cameras.

The R6 has a remote shutter port for an external intervalometer, or control via a time-lapse motion controller. That’s good!

However, the port is Canon’s low-grade 2.5mm jack. It works, and is a standard connector, but is not as sturdy as the three-pronged N3-style jack used on Canon’s 5D and 6D DSLRs, and on the R3 and R5. Considering the cost of the R6, I would have expected a better, more durable port. The On/Off switch also seems a bit flimsy and easily breakable under hard use.

The R6’s side ports, including the remote shutter/intervalometer port.

These deficiencies provide the impression of Canon unnecessarily “cheaping out” on the R6. You can forgive them with the Rp, but not with a semi-professional camera like the R6.

INTERVAL TIMER

Unlike the Canon R and Ra (which still mysteriously lack a built-in interval timer, despite firmware updates), the R6 has one in its firmware. Hurray! This can be used to set up a time-lapse sequence, but on exposures only up to the maximum of 30 seconds allowed by the camera’s shutter speed settings, true of most in-camera intervalometers.

For 30-second exposures taken in succession as quickly as possible the interval on the R6 has to be set to 34 seconds. The reason is that the 30-second exposure is actually 32 seconds, true of all cameras. With the R6, having a minimum gap in time between shots requires an Interval not of 33 seconds as with some cameras, but 34 seconds. Until you realize this, setting the intervalometer correctly can be confusing.

Like all Canon cameras, the R6 can be set to take only up to 99 frames, not 999. That seems a dumb deficiency. Almost all time-lapse sequences require at least 200 to 300 frames. What could it possibly take in the firmware to add an extra digit to the menu box? It’s there at in the Time-lapse Movie function that assembles a movie in camera, but not here where the camera shoots and saves individual frames. It’s another example where you just can’t fathom Canon’s software decisions.

**Setting the Interval Timer** for rapid sequence shots with a 30-second exposure.

TIP: If you want to shoot 100 or more frames, set the Number of Frames to 00, so it will shoot until you tell the camera to stop. But awkwardly, Canon says the way to stop an interval shoot is to turn off the camera! That’s crude, as doing so can force you to refocus if you are using a Canon RF lens. Switching the Mode dial to Bulb will stop an interval shoot, an undocumented feature.

BULB TIMER

As with most recent Canon DSLRs and DSLMs, the menu also includes a Bulb Timer. This allows setting an exposure of any length (many minutes or hours) when the camera is in Bulb mode. This is handy for single long shots at night.

However, it cannot be used in conjunction with the Interval Timer to program a series of multi-minute exposures, a pity. Instead, a separate outboard intervalometer has to be used for taking an automatic set of any exposures longer than 30 seconds, true of all Canons.

In Bulb and Bulb Timer mode, the R6’s rear screen lights up with a bright Timer readout. While the information is useful, the display is too bright at night and cannot be dimmed, nor turned red for night use, exactly when you are likely to use Bulb. The power-saving Eco mode has no effect on this display, precisely when you would want it to dim or turn off displays to prolong battery life, another odd deficiency in Canon’s firmware.

The Bulb Timer screen active during a Bulb exposure. At night it is bright!

The Timer display can only be turned off by closing the flip-out screen, but now the viewfinder activates with the same display. Either way, a display is on draining power during long exposures. And the Timer readout lacks any indication of battery level, a vital piece of information during long shoots. The Canon R, R3 and R5, with their top LCD screens, do not have this annoying “feature.”

TIP: End a Bulb Timer shoot prematurely by hitting the Shutter button. That feature is documented.

IN-CAMERA IMAGE STACKING

The R6 offers a menu option present on many recent Canon cameras: Multiple Exposure. The camera can take and internally stack up to 9 images, stacking them by using either Average (best for reducing noise) or Bright mode (best for star trails). An Additive mode also works for star trails, but stacking 9 images requires reducing the exposure of each image by 3 stops, say from ISO 1600 to ISO 200, as I did in the example below.

The result of the internal stacking is a raw file, with the option of also saving the component raws. While the options work very well, in all the cameras I’ve owned that offer such functions, I’ve never used them. I prefer to do any stacking needed later at the computer.

Comparing a single image with a stack of 9 exposures with **3 in-camera stacking methods.**

TIP: The in-camera image stacking options are good for beginners wanting to get advanced stacking results with a minimum of processing fuss later. Use Average to stack ground images for smoother noise. Use Bright for stacking sky images for star trails. Activate one of those modes, then control the camera with a separate intervalometer to automatically shoot and internally stack several multi-minute exposures.

SHUTTER OPERATION

Being a mirrorless camera, there is no reflex mirror to introduce vibration, and so no need for a mirror lockup function. The shutter can operate purely mechanically, with physical metal curtains opening and closing to start and end the exposure.

However, the default “out of the box” setting is Electronic First Curtain, where the actual exposure, even when on Bulb, is initiated electronically, but ended by the mechanical shutter. That’s good for reducing vibration, perhaps when shooting the Moon or planets through a telescope at high magnification.

In Mechanical, the physical curtains both start and end the exposure. It’s the mode I usually prefer, as I like to hear the reassuring click of the shutter opening. I’ve never found shutter vibration a problem when shooting deep sky images on a telescope mount of any quality.

In Mechanical mode the shutter can fire at up to 12 frames a second, or up to 20 frames a second in Electronic mode where both the start and end of the exposure happen without the mechanical shutter. That makes for very quiet operation, good for weddings and golf tournaments!

**Electronic Shutter Mode** is for fastest burst rates but has limitations.

Being vibration free, Electronic shutter might be great during total solar eclipses for rapid-fire bursts at second and third contacts when shooting through telescopes. Maximum exposure time is 1/2 second in this mode, more than long enough for capturing fleeting diamond rings.

Longer exposures needed for the corona will require Mechanical or Electronic First Curtain shutter. Combinations of shutter modes, drive rates (single or continuous), and exposure bracketing can all be programmed into the three Custom Function settings (C1, C2 and C3) on the Mode dial, for quick switching at an eclipse. It might not be until April 8, 2024 until I have a chance to test these features. And by then the R6 Mark II will be out!

TIP: While the R6’s manual doesn’t state it, some reviews mention (including at DPReview) that when the shutter is in fully Electronic mode the R6’s image quality drops from 14-bit to 12-bit, true of most other mirrorless cameras. This reduces dynamic range. I would suggest not using Electronic shutter for most astrophotography, even for exposures under 1/2 second. For longer exposures, it’s a moot point as it cannot be used.

The menu option that fouls up all astrophotographers using an R-series camera.

TIP: The R6 has the same odd menu item that befuddles many a new R-series owner, found on Camera Settings: Page 4. “Release Shutter w/o Lens” defaults to OFF, which means the camera will not work if it is attached to a manual lens or telescope it cannot connect to electronically. Turn it ON and all will be solved. This is a troublesome menu option that Canon should eliminate or default to ON.

OTHER MENU FEATURES

The rear screen is fully touch sensitive, allowing all settings to be changed on-screen if desired, as well as by scrolling with the joystick and scroll wheels. I find going back to an older camera without a touchscreen annoying – I keep tapping the screen expecting it to do something!

The Multi-Function Button brings up an array of 5 settings to adjust. This is ISO.

The little Multi-Function (M-Fn) button is a worth getting used to, as it allows quick access to a choice of five important functions such as ISO, drive mode and exposure compensation. However, the ISO, aperture and shutter speed are all changeable by the three scroll wheels.

The **Q button brings up the Quick Menu** for displaying and adjusting key functions.

There’s also the Quick menu activated by the Q button. While the content of the Quick menu screen can’t be edited, it does contain a good array of useful functions, adjustable with a few taps.

Under Custom settings, the **Dials and Buttons** can be re-assigned to other functions.

Unlike Sonys, the R6 has no dedicated Custom buttons per se. However, it does offer a good degree of customization of its buttons, by allowing users to re-assign them to other functions they might find more useful than the defaults. For example ….

This shows the AF Point button being re-assigned to the **Maximize Screen Brightness** (Temporary) command.

I’ve taken the AF Point button and assigned it to the Maximize Screen Brightness function, to temporarily boost the rear screen to full brightness for ease of framing.
The AE Lock button I assigned to switch the Focus Peaking indicators on and off, to aid manual focusing when needed.
The Depth of Field Preview button I assigned to switching between the rear screen and viewfinder, through that switch does happen automatically as you put your eye to the viewfinder.
The Set button I assigned to turning off the Rear Display, though that doesn’t have any effect when the Bulb Timer readout is running, a nuisance.

While the physical buttons are not illuminated, having a touch screen makes it less necessary to access buttons in the dark. It’s a pity the conveniently positioned but mostly unused Rate button can’t be re-programmed to more useful functions. It’s a waste of a button.

Set up the Screen Info as you like it by turning on and off screen pages and deciding what each should show.

TIP: The shooting screens, accessed by the Info button (one you do need to find in the dark!), can be customized to show a little, a lot, or no information, as you prefer. Take the time to set them up to show just the information you need over a minimum of screen pages.

LENS AND FILTER COMPATIBILITY

The new wider RF mount accepts only Canon and third-party RF lenses. However, all Canon and third-party EF mount lenses (those made for DSLRs) will fit on RF-mount bodies with the aid of the $100 Canon EF-to-RF lens adapter.

The **Canon ER-to-RF lens adapter** will be needed to attach R cameras to most telescope camera adapters and Canon T-rings made for older DSLR cameras.

This adapter will be necessary to attach any Canon R camera to a telescope equipped with a standard Canon T-ring. That’s especially true for telescopes with field flatterers where maintaining the standard 55mm distance between the flattener and sensor is critical for optimum optical performance.

The shallower “flange distance” between lens and sensor in all mirrorless cameras means an additional adapter is needed not just for the mechanical connection to the new style of lens mount, but also for the correct scope-to-sensor spacing.

The extra spacing provided by a mirrorless camera has the benefit of allowing a filter drawer to be inserted into the light path. Canon offers a $300 lens adapter with slide-in filters, though the choice of filters useful for astronomy that fit Canon’s adapter is limited. AstroHutech offers a few IDAS nebula filters.

Clip-in filters made for the EOS R, such as those offered by Astronomik, will also fit the R6. Though, again, most narrowband filters will not work well with an unmodified camera.

The **AstroHutech adapter** allows inserting filters into the light path on telescopes.

TIP: Alternatively, AstroHutech also offers its own lens adapter/filter drawer that goes from a Canon EF mount to the RF mount, and accepts standard 52mm or 48mm filters. It is a great way to add interchangeable filters to any telescope when using an R-series camera, while maintaining the correct back-focus spacing. I use an AstroHutech drawer with my Ra, where the modified camera works very well with narrowband filters. Using such filters with a stock R6 won’t be as worthwhile, as I showed above.

A trio of Canon RF zooms — all superb but quite costly.

As of this writing, the selection of third-party lenses for the Canon RF mount is limited, as neither Canon or Nikon have “opened up” their system to other lens makers, unlike Sony with their E-mount system. For example, we have yet to see much-anticipated RF-mount lenses from Sigma, Tamron and Tokina.

A trio of **third party RF lenses** — L to R: the TTArtisan 7.5mm f/2 and 11mm f/2.8 fish-eyes and the Samyang/Rokinon AF 85mm f/1.4.

Samyang offers 14mm and 85mm auto-focus RF lenses, but now only under their Rokinon branding. I tested the Samyang RF 85mm f/1.4 here at AstroGearToday.

The few third-party lenses that are available, from TTArtisan, Venus Optics and other boutique Chinese lens companies, are usually manual focus lenses with reverse-engineered RF mounts offering no electrical contact with the camera. Some of these wide-angle lenses are quite good and affordable. (I tested the TTArtisan 11mm fish-eye here.)

Until other lens makers are “allowed in,” if you want lenses with auto-focus and camera metadata connections, you almost have to buy Canon. Their RF lenses are superb, surpassing the quality of their older EF-mount equivalents. But they are costly. I sold off a lot of my older lenses and cameras to help pay for the new Canon glass!

I also have reviews of the superb Canon RF 15-35mm f/2.8, as well as the unique Canon RF 28-70mm f/2 and popular Canon RF 70-200mm f/2.8 lenses (a trio making up the “holy trinity” of zooms) at AstroGearToday.com.

CONTROL COMPATIBILITY

Astrophotographers often like to operate their cameras at the telescope using computers running specialized control software. I tested the R6 with two popular Windows programs for controlling DSLR and now mirrorless cameras, BackyardEOS (v3.2.2) and AstroPhotographyTool (v3.88). Both recognized and connected to the R6 via its USB port.

Another popular option is the ASIair WiFi controller from ZWO. It controls cameras via one of the ASIair’s USB ports, and not (confusingly) through the Air’s remote shutter jack marked DSLR. Under version 1.7 of its mobile app, the ASIair now controls Canon R cameras and connected to the R6 just fine, allowing images to be saved both to the camera and to the Air’s own MicroSD card.

With an update in 2021, the **ZWO** **ASIair** now operates Canon R-series cameras.

The ASIair is an excellent solution for both camera control and autoguiding, with operation via a mobile device that is easier to use and power in the field than a laptop. I’ve not tried other hardware and software controllers with the R6.

TIP: While the R6, like many Canon cameras, can be controlled remotely with a smartphone via the CanonConnect mobile app, the connection process is complex and the connection can be unreliable. The Canon app offers no redeeming features for astrophotography, and maintaining the connection via WiFi or Bluetooth consumes battery power.

A dim red and green aurora from Dinosaur Provincial Park, Alberta, on August 29/30, 2021. This is a stack of 4 exposures for the ground to smooth noise and one exposure for the sky, all 30 seconds at f/2.8 with the Canon 15-35mm RF lens at 25mm and the Canon R6 at ISO 4000.

SUGGESTIONS TO CANON

To summarize, in firmware updates, Canon should:

Fix the low-level amp glow. No camera should have amp glow.
Allow either dimming the Timer readout, turning it red, or just turning it off!
Add a battery display to the Timer readout.
Expand the Interval Timer to allow up to 999 frames, as in the Time-Lapse Movie.
Allow the Rate button to be re-assigned to more functions.
Default the Release Shutter w/o Lens function to ON.
Revise the manual to correctly describe how to stop an Interval Timer shoot.
Allow programming multiple long exposures by combining Interval and Bulb Timer, or by expanding the shutter speed range to longer than 30 seconds, as some Nikons can do.

The Zodiacal Light in the dawn sky, September 14, 2021, from home in Alberta, with the winter sky rising. This is a stack of 4 x 30-second exposures for the ground to smooth noise, and a single 30-second exposure for the sky, all with the TTArtisan 7.5mm fish-eye lens at f/2 and on the Canon R6 at ISO 1600.

CONCLUSION

The extended red sensitivity of the Canon EOS Ra makes it better suited for deep-sky imaging. But with it now out of production (Canon traditionally never kept its astronomical “a” cameras in production for more than two years), I think the R6 is now Canon’s best camera (mirrorless or DSLR) for all types of astrophotography, both stills and movies.

However, I cannot say how well it will work when filter-modified by a third-party. But such a modification is necessary only for recording red nebulas in the Milky Way. It is not needed for other celestial targets and forms of astrophotography.

A composite showing about three dozen Perseid meteors accumulated over 3 hours of time, compressed into one image showing the radiant point of the meteor shower in Perseus. All frames were with the Canon R6 at ISO 6400 and with the TTArtisan 11mm fish-eye lens at f/2.8.

The low noise and ISO invariant sensor of the R6 makes it superb for nightscapes, apart from the nagging amp glow. That glow will also add an annoying edge gradient to deep-sky images, best dealt with when shooting by the use of LENR or dark frames.

As the image of the Andromeda Galaxy, M31, at the top of the blog attests, with careful processing it is certainly possible to get fine deep-sky images with the R6.

For low-light movies the R6 is Canon’s answer to the Sony alphas. No other Canon camera can do night sky movies as well as the R6. For me, it was the prime feature that made the R6 the camera of choice to complement the Ra.

The Nikkor 20mm S-Line Lens ($1,050)

The Viltrox AF 16mm STM ASPH ED IF ($580)

The Venus Optics/Laowa 10mm Zero-D FF ($800)

BONUS TEST: The TTArtisan 7.5mm f/2 Fish-Eye ($140)

Recommendations

Share this:

Out with the Old …

Polar Alignment Accessories

Tracking Accuracy

Mechanical Stability

Simplicity of Operation

Collisions

Collision Avoidance

Recommendations

Share this:

AI-based noise reduction programs continue to improve, to provide remarkable results on many images. But … how well do they work on star-filled astrophotos?

MY METHODS (“BUT WHAT ABOUT …?”)

TL;DR SUMMARY (with links to the software websites)

RAW-ONLY PROGRAMS — NIGHTSCAPES

RAW-ONLY PROGRAMS — AURORA

RAW-ONLY PROGRAMS — SOLAR ECLIPSE

RAW-ONLY PROGRAMS — DEEP-SKY

OTHER PROGRAMS — WORKING STAND-ALONE ON RAW FILES

THE SAME TRIO — AS PLUG-INS WITHIN PHOTOSHOP

SPECIALIZED PROGRAMS — NOISE XTERMINATOR and GRAXPERT

YOUR MILEAGE MAY VARY!

Share this:

GEAR AND FILTERS

TESTING, TESTING!

WIDE-FIELD OPTIONS

Share this:

TL;DR Conclusions

Avoiding Adobe?

Raw Editing vs. Layer-Based Editing

The Challenge

The Competitors

Feature Focus

Summary Comparison Table

Feature-by-Feature Details — 1. Browsing and Cataloging

Feature-by-Feature Details — 2. Lens Corrections

Feature-by-Feature Details — 3. Noise Reduction and Sharpening

Feature-by-Feature Details — 4. Shadow Recovery

Feature-by-Feature Details — 5. Local Adjustments and Masking

Feature-by-Feature Details — 6. Overall Finished Image Quality

Feature-by-Feature Details — 7. Copy & Paste Settings

Feature-by-Feature Details — 8. Batch Export

Feature-by-Feature Details — 9. Advanced Features

Program-by-Program Summary

Why Didn’t I Test …?

Recommendations

Finally — Download Trials and Test!

Share this:

TL;DR SUMMARY

METHODOLOGY

THE CONTENDERS

NIGHTSCAPE TEST

WIDE-FIELD IMAGE TEST

TELESCOPIC DEEP-SKY TEST

COMPARING DxO and TOPAZ OPTIONS

APRIL 2023 UPDATE — TESTING ADOBE’S NEW AI Denoise

COMPARING AI TO OLDER NON-AI PROGRAMS

YOUR RESULTS MAY VARY

WHAT ABOUT ADOBE?

Share this:

METHODOLOGY

TL;DR SUMMARY

Lens Specs and Applications

Centre Sharpness

Corner Aberrations

Frame Vignetting

LENS Corrections

Same Focal Length Comparisons

Compared to DSLR Lenses

Mechanical Points

FINISHED IMAGES GALLERIES

CONCLUSIONs and recommendations

Share this:

TL;DR Summary

R5 Pros

R5 Cons