Testing the Nikon Z6 for Astrophotography


Nikon Z Title

I put the new Nikon Z6 mirrorless camera through its paces for astrophotography. 

Following Sony’s lead, in late 2018 both Nikon and Canon released their entries to the full-frame mirrorless camera market. 

Here I review one of Nikon’s new mirrorless models, the Z6, tested solely with astrophotography in mind. I did not test any of the auto-exposure, auto-focus, image stabilization, nor rapid-fire continuous mode features. 

For full specs and details on the Z-series cameras see Nikon USA’s website.

Sony a7III vs Nikon Z6 copy

In my testing I compared the Nikon Z6 (at right above) to two competitive cameras, the relatively new Sony a7III mirrorless (at left above) and 2015-vintage Nikon D750 DSLR.

All three are “entry-level” full-frame cameras, with 24 megapixels and in a similar $2,000 price league, though the older D750 now often sells at a considerable discount.


Disclosure

I should state at the outset that my conclusions are based on tests conducted over only three weeks in mid-winter 2019 while I had the camera on loan from Nikon Canada’s marketing company. 

I don’t own the camera and didn’t have many moonless nights during the loan period to capture a lot of “beauty” shots under the stars with the Z6.

Auroral Arc (January 10, 2019)
An arc of the auroral oval across the northern horizon on the night of January 10-11, 2019. With the Sigma 14mm lens and Nikon Z6 for testing.

However, I think my testing was sufficient to reveal the camera’s main traits of interest — as well as deficiencies it might have — for astrophotography.

I should also point out that I do not participate in “affiliate links,” so I have no financial motivation to prompt you to buy gear from merchants. 

But if you buy my ebook (at right), which features reams of sections on camera and time-lapse gear, I would be very pleased! 


TL;DR Conclusions

In short — I found the Nikon Z6 superb for astrophotography. 

Nikon Z6 Screens copy

Summary:

• It offers as low a noise level as you’ll find in a 24-megapixel full-frame camera, though its noise was not significantly lower than the competitive Sony a7III, nor even the older Nikon D750. 

• The Z6’s ISO-invariant sensor proved excellent when dealing with the dark underexposed shadows typical of Milky Way nightscapes.

• The Live View was bright and easy to enhance to even brighter levels using the Movie mode to aid in framing nightscapes. 

• When shooting deep-sky images through telescopes using long exposures, the Z6 did not exhibit any odd image artifacts such as edge vignetting or amplifier glows, unlike the Sony a7III. See my review of that camera in my blog from 2018. 

Recommendations: 

• Current owners of Nikon cropped-frame cameras wanting to upgrade to full-frame would do well to consider a Z6 over any current Nikon DSLR. 

• Anyone wanting a full-frame camera for astrophotography and happy to “go Nikon” will find the Z6 nearly perfect for their needs. 


Nikon Z6 vs. Z7

Nikon Front View copy

I opted to test the Z6 over the more expensive Z7, as the 24-megapixel Z6 has 6-micron pixels resulting in lower noise (according to independent tests) than the 46 megapixel Z7 with its 4.4 micron pixels. 

In astrophotography, I feel low noise is critical, with 24-megapixel cameras hitting a sweet spot of noise vs. resolution.

However, if the higher resolution of the Z7 is important for your daytime photography needs, then I’m sure it will work well at night. The Nikon D850 DSLR, with a sensor similar to the Z7, has been proven by others to be a good astrophotography camera, albeit with higher noise than the lesser megapixel Nikons such as the D750 and Z6.

NOTE: Tap or click on images to download and display them full screen for closer inspection.


High ISO Noise

Comparison - Noise at 3 ISOs
The three 24-megapixel cameras compared at three high ISO levels in a close-up of a dark-sky nightscape.

To test noise in a real-world situation, I shot a dark nightscape scene with the three cameras, using a 24mm Sigma Art lens on the two Nikons, and a 24mm Canon lens on the Sony via a MetaBones adapter. I shot at ISOs from 800 to 12,800, typical of what we use in nightscapes and deep-sky images. 

The comparison set above shows performance at the higher ISOs of 3200 to 12,800. I saw very little difference among the trio, with the Nikon Z6 very similar to the Sony a7III, and with the four-year-old Nikon D750 holding up very well against the two new cameras. 

The comparison below shows the three cameras on another night and at ISO 3200.

Noise at 3200-3 Cameras
The three cameras compared for noise at properly exposed moonlit scenes at ISO 3200, a typical nightscape setting.

Both the Nikon Z6 and Sony a7III use a backside illuminated or “BSI” sensor, which in theory is promises to provide lower noise than a conventional CMOS sensor used in an older camera such as the D750. 

In practice I didn’t see a marked difference, certainly not as much as the one- or even 1/2-stop improvement in noise I might have expected or hoped for.

Nevertheless, the Nikon Z6 provides as low a noise level as you’ll find in a camera offering 24 megapixels, and will perform very well for all forms of astrophotography. 


ISO Invariance

Comparison - ISO Invariancy
The three cameras compared for ISO invariance at 0EV (well exposed) and -5EV (5 stops underexposed then brightened in processing).

Nikon and Sony both employ an “ISO-invariant” signal flow in their sensor design. You can purposely underexpose by shooting at a lower ISO, then boost the exposure later “in post” and end up with a result similar to an image shot at a high ISO to begin with in the camera. 

I find this feature proves its worth when shooting Milky Way nightscapes that often have well-exposed skies but dark foregrounds lit only by starlight. Boosting the brightness of the landscape when developing the raw files reveals details in the scene without unduly introducing noise, banding, or other artifacts such as magenta tints. 

That’s not true of “ISO variant” sensors, such as in most Canon cameras. Such sensors are far less tolerant of underexposure and are prone to noise, banding, and discolouration in the brightened shadows.

See my test of the Canon 6D MkII for its performance under the differing demands of nightscape photography and deep-sky imaging.

To test the Z6’s ISO invariance (as shown above) I shot a dark nightscape at ISO 3200 for a properly exposed scene, and also at ISO 100 for an image underexposed by a massive 5 stops. I then boosted that image by 5 stops in exposure in Adobe Camera Raw. That’s an extreme case to be sure. 

I found the Z6 provided very good ISO invariant performance, though with more chrominance specking than the Sony a7III and Nikon D750 at -5 EV.

Below is a less severe test, showing the Z6 properly exposed on a moonlit night and at 1 to 4 EV steps underexposed, then brightened in processing. Even the -4 EV image looks very good.

Comparison-ISO Invariancy in Moonlight
This series taken under moonlight shows that even images underexposed by -4 EV in ISO and boosted later by +4 EV in processing look similar for noise and image quality as an image properly exposed in the camera (at ISO 800 here).

In my testing, even with frames underexposed by -5 EV, I did not see any of the banding effects (due to the phase-detect auto-focus pixels) reported by others. 

As such, I judge the Z6 to be an excellent camera for nightscape shooting when we often want to extract detail in the shadows or dark foregrounds. 


Compressed vs. Uncompressed / Raw Large vs. Small 

Comparison - Z6 Large vs Medium RAW
Comparing Z6 images shot at full resolution and at Medium Raw size. to show resolution and noise differences.

The Z6, as do many Nikons, offers a choice of shooting 12-bit or 14-bit raws, and either compressed or uncompressed. 

I shot all my test images as 14-bit uncompressed raws, yielding 46 megabyte files with a resolution of 6048 x 4024 pixels. So I cannot comment on how good 12-bit compressed files are compared to what I shot. Astrophotography demands the best original data. 

Z6 Menu - Raw Formats

However, as the menu above shows, Nikon now also offers the option of shooting smaller raw sizes. The Medium Raw setting produces an image 4528 x 3016 pixels and a 18 megabyte file (in the files I shot), but with all the benefits of raw files in processing.

Nikon with Card Slot copy
The Z cameras use the XQD style memory cards and in a single card slot. The fast XQDs are ideal for recording 4K movies at high data rates but are more costly than the more common SD cards.

The Medium Raw option might be attractive when shooting time-lapses, where you might need to fit as many frames onto the single XQD card as possible, yet still have images large enough for final 4K movies. 

However, comparing a Large Raw to a Medium Raw did show a loss of resolution, as expected, with little gain in noise reduction. 

This is not like “binning pixels” in CCD cameras to increase signal-to-noise ratio. I prefer to never throw away information in the camera, to allow the option of creating the best quality still images from time-lapse frames later. 

Nevertheless, it’s nice to see Nikon now offer this option on new models, a feature which has long been on Canon cameras. 


Star Image Quality

Orion Nebula, M42 and M43, with Nikon Z6
The Orion Nebula with the Nikon Z6
The Orion Nebula in Moonlight
The Orion Nebula with the Nikon D750

Above is the Orion Nebula with the D750 and with the Z6, both shot in moonlight with the same 105mm refractor telescope.

I did not find any evidence for “star-eating” that Sony mirrorless cameras have been accused of. (However, I did not find the Sony a7III guilty of eating stars either.) Star images looked as good in the Z6 as in the D750. 

M42 Blow-up in ACR
A single Orion Nebula image with the Z6 in a 600% blow-up in Adobe Camera Raw, showing clean artifact-free star images with good, natural colours.

Raw developers (Adobe, DxO, ON1, and others) decoded the Z6’s Bayer-array NEF files fine, with no artifacts such as oddly-coloured or misshapen stars, which can arise in cameras lacking an anti-alias filter. 


LENR Dark frames 

Z6 Dark Frame- No LENR
A blank long exposure with no LENR applied – click or tap to open the image full screen
Z6 Dark Frame-With LENR
A blank long exposure with LENR – tap or click to open the image full screen

Above, 8-minute exposures of nothing, taken with the lens cap on at room temperature: without LENR, and with LENR, both boosted a lot in brightness and contrast to exaggerate the visibility of any thermal noise. These show the reduction in noise speckling with LENR activated, and the clean result with the Z6. At small size you’ll likely see nothing but black!

For deep-sky imaging a common practice is to shoot “dark frames,” images recording just the thermal noise that can then be subtracted from the image. 

The Long Exposure Noise Reduction feature offered by all cameras performs this dark frame subtraction internally and automatically by the camera for any exposures over one second long. 

I tested the Z6’s LENR and found it worked well, doing the job to effectively reduce thermal noise (hot pixels) without adding any other artifacts. 

Z6 iMenu Screen
The rear screen “i” menu as I had it customized for my testing, with functions for astrophotography such as LENR assigned to the 12 boxes.

NOTE:

Some astrophotographers dismiss LENR and never use it. By contrast, I prefer to use LENR to do dark frame subtraction. Why? Through many comparison tests over the years I have found that separate dark frames taken later at night rarely do as good a job as LENR darks, because those separate darks are taken when the sensor temperature, and therefore the noise levels, are different than they were for the “light” frames. 

I’ve found that dark frames taken later, then subtracted “in post” inevitably show less or little effect compared to images taken with LENR darks. Or worse, they add a myriad of pock-mark black specks to the image, adding noise and making the image look worse.

The benefit of LENR is lower noise. The penalty of LENR is that each image takes twice as long to shoot — the length of the exposure + the length of the dark frame. Because …


As Expected on the Z6 … There’s no LENR Dark Frame Buffer

Only Canon full-frame cameras offer this little known but wonderful feature for astrophotography. Turn on LENR and it is possible to shoot three (with the Canon 6D MkII) or four (with the Canon 6D) raw images in quick succession even with LENR turned on. The Canon 5D series also has this feature. 

The single dark frame kicks in and locks up the camera only after the series of “light frames” are taken. This is excellent for taking a set of noise-reduced deep-sky images for later stacking without need for further “image calibration.” 

No Nikon has this dark frame buffer, not even the “astronomical” D810a. And not the Z6.

ANOTHER NOTE: 

I have to mention this every time I describe Canon’s dark frame buffer: It works only on full-frame Canons, and there’s no menu function to activate it. Just turn on LENR, fire the shutter, and when the first exposure is complete fire the shutter again. Then again for a third, and perhaps a fourth exposure. Only then does the LENR dark frame lock up the camera as “Busy” and prevent more exposures. That single dark frame gets applied to each of the previous “light” frames, greatly reducing the time it takes to shoot a set of dark-frame subtracted images. 

But do note that Canon’s dark frame buffer will not work if…:

a) You leave Live View on. Don’t do that for any long exposure shooting.

b) You control the camera through the USB port via external software. It works only when controlling the camera via its internal intervalometer or via the shutter port using a hardware intervalometer.


Sensor Illumination 

M35 with Z6 & Traveler (4 Minutes)
A single 4-minute exposure of Messier 35 in moonlight at ISO 400 with the Z6 and 105mm apo refractor, with no flat fielding or lens correction applied, showing the clean edges and lack of amp glows. The darkening of the corners is inherent in the telescope optical system and is not from the camera.

With DSLRs deep-sky images shot through telescopes, then boosted for contrast in processing, usually exhibit a darkening along the bottom of the frame. This is caused by the upraised mirror shadowing the sensor slightly, an effect never noticed in normal photography. 

Mirrorless cameras should be free of this mirror box shadowing. The Sony a7III, however, still exhibits some edge shadows due to an odd metal mask in front of the sensor. It shouldn’t be there and its edge darkening is a pain to eliminate in the final processing. 

As I show in my review of the a7III, the Sony also exhibits a purple edge glow in long-exposure deep-sky images, from an internal light source. That’s a serious detriment to its use in deep-sky imaging.

Happily, the Z6 proved to be free of any such artifacts. Images are clean and evenly illuminated to the edges, as they should be. I saw no amp glows or other oddities that can show up under astrophotography use. The Z6 can produce superb deep-sky images. 


Red Sensitivity

M97 with Z6 & Traveler (4 Minutes)
Messer 97 planetary nebula and Messier 108 galaxy in a lightly processed single 4-minute exposure at ISO 1600 with the 105mm refractor, again showing a clean field. The glow at top right is from a Big Dipper star just off the edge of the field.

During my short test period, I was not able to shoot red nebulas under moonless conditions. So I can’t say how well the Z6 performs for recording H-alpha regions compared to other “stock” cameras. 

However, I would not expect it to be any better, nor worse, than the competitors. Indeed, the stock Nikon D750 I have does a decent job at picking up red nebulas, though nowhere near as well as Nikon’s sadly discontinued D180a. See my blog post from 2015 for an example shot with that camera. 

With the D810a gone, if it is deep red nebulosity you are after with a Nikon, then consider buying a filter-modified Z6 or having yours modified. 

Both LifePixel and Spencer’s Camera offer to modify the Z6 and Z7 models. However, I have not used either of their services, so cannot vouch for them first hand. 


Live View Focusing and Framing 

Z6 Live View Screen
An image of the back of the camera with a scene under moonlight, with the Z6 set to the highest ISO speed in the movie mode, to aid framing the scene at night.

For all astrophotography manually focusing with Live View is essential. And with mirrorless cameras there is no optical viewfinder to look through to frame scenes. You are dependent on the live electronic image (on the rear LCD screen or in the eye-level electronic viewfinder, or EVF) for seeing anything.

Thankfully, the Z6 presents a bright Live View image making it easy to frame, find, and focus on stars. Maximum zoom for precise focusing is 15x, good but not as good as the D750’s 20x zoom level, but better than Canon’s 10x maximum zoom in Live View. 

The Z6 lacks the a7III’s wonderful Bright Monitoring function that temporarily ups the ISO to an extreme level, making it much easier to frame a dark night scene. However, something similar can be achieved with the Z6 by switching it temporarily to Movie mode, and having the ISO set to an extreme level.

As with most Nikons (and unlike Sonys), the Z6 remembers separate settings for the still and movie modes, making it easy to switch back and forth, in this case for a temporarily brightened Live View image to aid framing. 

That’s very handy, and the Z6 works better than the D750 in this regard, providing a brighter Live View image, even with the D750’s well-hidden Exposure Preview option turned on. 


Video Capability 

Comparison - Movie Noise Levels
Comparing the three cameras using 1/25-second still frames grabbed from moonlit night movies (HD with the D750 and 4K with the Z6 and a7III) shot at ISO 51200, plus a similarly exposed frame from the a7III shot with a shutter speed of only 1/4 second allowing the slower ISO of 8000.

Where the Z6 pulls far ahead of the otherwise similar D750 is in its movie features.

The Z6 can shoot 4K video (3840 x 2160 pixels) at either 30, 25, or 24 frames per second. Using 24 frames per second and increasing the ISO to between 12,800 to 51,200 (the Z6 can go as high as ISO 204,800!) it is possible to shoot real-time video at night, such as of auroras.

But the auroras will have to be bright, as at 24 fps, the maximum shutter speed is 1/25-second, as you might expect. 

The a7III, by comparison, can shoot 4K movies at “dragged” shutter speeds as slow as 1/4 second, even at 24 fps, making it possible to shoot auroras at lower and less noisy ISO speeds, albeit with some image jerkiness due to the longer exposures per frame. 

The D750 shoots only 1080 HD and, as shown above, produces very noisy movies at ISO 25,600 to 51,200. It’s barely usable for aurora videos.

The Z6 is much cleaner than the D750 at those high ISOs, no doubt due to far better internal processing of the movie frames. However, if night-sky 4K videos are an important goal, a camera from the Sony a7 series will be a better choice, if only because of the option for slower dragged shutter speeds.

For examples of real-time auroras shot with the Sony a7III see my music videos shot in Yellowknife and in Norway. 


Battery Life

Nikon Z6 Battery copy

The Z6 uses the EN-EL15b battery compatible with the battery and charger used for the D750. But the “b” variant allows for in-camera charging via the USB port. 

In room temperature tests the Z6 lasted for 1500 exposures, as many as the D750 was able to take in a side-by-side test. That was with the screens off.

At night, in winter temperatures of -10 degrees C (14° F), the Z6 lasted for three hours worth of continuous shooting, both for long deep-sky exposure sets and for a test time-lapse I shot, shown below. 

A time-lapse movie, downsized here to HD from the full-size originals, shot with the Z6 and its internal intervalometer, from twilight through to moonrise on a winter night. Processed with Camera Raw and LRTimelapse. 

However, with any mirrorless camera, you can extend battery life by minimizing use of the LCD screen and eye-level EVF. The Z6 has a handy and dedicated button for shutting off those screens when they aren’t needed during a shoot.

The days of mirrorless cameras needing a handful of batteries just to get through a few hours of shooting are gone. 


Lens and Telescope Compatibility 

Nikon with Sigma and FTZ copy
A 14mm Sigma Art lens with the Nikon FTZ lens adapter needed to attach any “legacy” F-mount lens to the Z6.

As with all mirrorless cameras, the Nikon Z cameras use a new lens mount, one that is incompatible with the decades-old Nikon F mount. 

The Z mount is wider and can accommodate wider-angle and faster lenses than the old F mount ever could, and in a smaller package. While we have yet to see those lenses appear, in theory that’s the good news.

The bad news is that you’ll need Nikon’s FTZ lens adapter to use any of your existing Nikon F-mount lenses on either the Z6 or Z7. As of this writing, Nikon is supplying an FTZ free with every Z body purchase. 

I got an FTZ with my loaner Z6 and it worked very well, allowing even third-party lenses like my Sigma Art lenses to focus at the same point as they normally do (not true of some thIrd-party adapters), preserving the lens’s optical performance. Autofocus functions all worked fine and fast.

Nikon with Scope Adapter and FTZ copy
The FTZ adapter needed to attach the Z6 to a telescope camera adapter (equipped with a standard Nikon T-ring) and field flattener lens for a refractor.

You’ll also need the FTZ adapter for use on a telescope, as shown above, to go from your telescope’s camera adapter, with its existing Nikon T-ring, to the Z6 body. 

T-rings are becoming available for the Z-mount, but even these third-party adapters are actually extension tubes, not just rings.

The reason is that the field flattener or coma corrector lenses often required with telescopes are designed to work best with the longer lens-to-sensor distance of a DSLR body. The FTZ adapter provides the necessary spacing, as do third-party adapters. 

Nikon Z6 FTZ Foot copy
The FTZ lens adapter has its own tripod foot, useful for balancing front-heavy lenses like the big Sigma here.

The only drawback to the FTZ is that any tripod plate attached to the camera body itself likely has to come off, and the tripod foot incorporated into the FTZ used instead. I found myself often having to swap locations for the tripod plate, an inconvenience. 


Camera Controller Compatibility 

Nikon with Ports copy
The port side of the Z6, with the DC2 shutter remote jack at bottom, and HDMI and USB-C ports above. There’s also a mic and headphone jack for video use.

Since it uses the same Nikon-type DC2 shutter port as the D750, the Z6 it should be compatible with most remote hardware releases and time-lapse motion controllers that operate a Nikon through the shutter port. An example are the controllers from SYRP.

On the other hand, time-lapse devices and external intervalometers that run Nikons through the USB port might need to have their firmware or apps updated to work with the Z6.

For example, as of early May 2019, CamRanger lists the Z6 as a supported camera; the Arsenal “smart controller” does not. Nor does Alpine Labs for their Radian and Pulse controllers, nor TimeLapse+ for its excellent View bramping intervalometer. Check with your supplier.

For those who like to use laptops to run their camera at the telescope, I found the Windows program Astro Photography Tool (v3.63) worked fine with the Z6, in this case connecting to the camera’s USB-C port using the USB-C to USB-A cable that comes with the camera. This allows APT to shift not only shutter speed, but also ISO and aperture under scripted sequences. 

However, BackyardNikon v2.0, current as of April 2019, does not list the Z6 as a supported camera. 


Raw File Compatibility 

Z6 Raw open in Raw Therapee
A Z6 Raw NEF file open in Raw Therapee 5.6, showing good star images and de-Bayering.

Inevitably, raw files from brand new cameras cannot be read by any raw developer programs other than the one supplied by the manufacturer, Nikon Capture NX in this case. However, even by the time I did my testing in winter 2019 all the major software suppliers had updated their programs to open Z6 files. 

Adobe Lightroom and Photoshop, Affinity Photo, DxO PhotoLab, Luminar 3, ON1 PhotoRAW, and the open-source Raw Therapee all open the Z6’s NEF raw files just fine. 

Z6 Raw in PixInsight
PixInsight 1.8.6 failing to open a Z6 raw NEF file.

Specialized programs for processing astronomy images might be another story. For example, as of v1.08.06, PixInsight, a favourite program among astrophotographers, does not open Z6 raw files. Nor does Nebulosity v4. But check with the developers for updates. 


Other Features for Astrophotography 

Here are other Nikon Z6 features I found of value for astrophotography, and for operating the camera at night. 

Nikon with Looking Right copy

Tilting LCD Screen 

Like the Nikon D750 and Sony A7III, the Z6 offers a tilting LCD screen great for use on a telescope or tripod when aimed up at the sky. However, the screen does not flip out and reverse, a feature useful for vloggers, but seldom needed for astrophotography. 

Nikon Z6 Top Screen copy
Showing the top OLED screen and dedicated ISO button that is easy to access in the dark. It works in conjunction with the top dial.

OLED Top Screen (Above)

The Sony doesn’t have one, and Canon’s low-cost mirrorless Rp also lacks one. But the top-mounted OLED screen of the Z6 is a great convenience for astrophotography. It makes it possible to monitor camera status and battery life during a shoot, even with the rear LCD screen turned off to prolong battery life.

Z6 Menu - Quick Menu

Touch Screen 

Sony’s implementation of touch-screen functions is limited to just choosing autofocus points. By contrast, the Nikon Z6 offers a full range of touchscreen functions, making it easy to navigate menus and choose settings. 

I do wish there was an option, as there is with Pentax, to tint the menus red for preserving night vision.

Z6 Menu - Intervalometer

Built-in Intervalometer

As with other Nikons, the Z6 offers an internal intervalometer capable of shooting time-lapses, just as long as individual exposures don’t need to be longer than 30 seconds. 

In addition, there’s the Exposure Smoothing option which, as I have found with the D750, is great for smoothing flickering in time-lapses shot using auto exposure. 

Sony has only just added an intervalometer to the a7III with their v3 firmware update, but with no exposure smoothing. 

Z6 Menu - Silent Shooting

Custom i Menu / Custom Function Buttons 

The Sony a7III has four custom function buttons users can assign to commonly used commands, for quick access. For example, I assign one Custom button to the Bright Monitoring function which is otherwise utterly hidden in the menus, but superb for framing nightscapes, if only you know it’s there! 

The Nikon Z6 has two custom buttons beside the lens mount. However, I found it easier to use the “i” menu (shown above) by populating it with those functions I use at night for astrophotography. It’s then easy to call them up and adjust them on the touch screen.

Thankfully, the Z6’s dedicated ISO button is now on top of the camera, making it much easier to find at night than the awkwardly placed ISO button on the back of the D750, which I am always mistaking for the Image Quality button, which you do not want to adjust by mistake. 

Nikon Z6-My Menu

My Menu 

As most cameras do, the Z6 also has a “My Menu” page which you can also populate with favourite menu commands. 

Nikon D750 and Z6 copy
The D750 (left) compared to the smaller and lighter Z6 (right). This shows the wider Z lens mount compared to Nikon’s old F-mount standard.

Lighter Weight / Smaller Size

The Z6 provides similar imaging performance, if not better (for movies) than the D750, and in a smaller and lighter camera, weighing 200 grams (0.44 pounds) less than the D750. Being able to downsize my equipment mass is a welcome plus to going mirrorless.

Comparison - Z6 Mech vs Silent Shutter
Extreme 800% blow-ups of the Moon show a slightly sharper image with the Z6 set to Silent Shutter.

Electronic Front Curtain Shutter / Silent Shooting 

By design, mirrorless cameras lack any vibration from a bouncing mirror. But even the mechanical shutter can impart vibration and blurring to high-magnification images taken through telescopes. 

The electronic front curtain shutter (lacking in the D750) helps eliminate this, while the Silent Shooting mode does just that — it makes the Z6 utterly quiet and vibration free when shooting, as all the shutter functions are now electronic. This is great for lunar and planetary imaging. 


What’s Missing for Astrophotography (not much!)

Bulb Timer for Long Exposures

While the Z6 has a Bulb setting, there is no Bulb Timer as there is with Canon’s recent cameras. A Bulb Timer would allow setting long Bulb exposures of any length in the camera, though Canon’s cannot be combined with the intervalometer. 

Instead, the Nikon must be used with an external Intervalometer for any exposures over 30 seconds long. Any number of units are compatible with the Z6, through its shutter port which is the same type DC2 jack used in the D750.

Z6 Menu - Multiple Exposures

In-Camera Image Stacking to Raws

The Z6 does offer the ability to stack up to 10 images in the camera, a feature also offered by Canon and Pentax. Images can be blended with a Lighten (for star trails) or Average (for noise smoothing) mode. 

However, unlike with Canon and Pentax, the result is a compressed JPG not a raw file, making this feature of little value for serious imaging. Plus with a maximum of only 10 exposures of up to 30-seconds each, the ability to stack star trails “in camera” is limited. 

Illuminated Buttons 

Unlike the top-end D850, the Z6’s buttons are not illuminated, but then again neither are the Z7’s.


As a bonus — the Nikon 35mm S-Series Lens

Nikkor 35mm Lens Test
The upper left frame corner of a tracked star image shot with the 35mm S lens wide open at f/1.8 and stopped down at third stop increments.

With the Z6 I also received a Nikkor 35mm f/1.8 S lens made for the Z-mount, as the lens perhaps best suited for nightscape imaging out of the native Z-mount lenses from Nikon. See Nikon’s website for the listing. 

If there’s a downside to the Z-series Nikons it’s the limited number of native lenses that are available now from Nikon, and likely in the future from anyone, due to Nikon not making it easy for other lens companies to design for the new Z mount. 

In testing the 35mm Nikkor on tracked shots, stars showed excellent on- and off-axis image quality, even wide open at f/1.8. Coma, astigmatism, spherical aberration, and lateral chromatic aberration were all well controlled. 

However, as with most lenses now offered for mirrorless cameras, the focus is “by-wire” using a ring that doesn’t mechanically adjust the focus. As a result, the focus ring turns continuously and lacks a focus scale. 

So it is not possible to manually preset the lens to an infinity mark, as nightscape photographers often like to do. Focusing must be done each night. 

Until there is a greater selection of native lenses for the Z cameras, astrophotographers will need to use the FTZ adapter and their existing Nikon F-mount or third-party Nikon-mount lenses with the Zs.


Recommendations 

I was impressed with the Z6. 

The Owl Nebula and Messier 108 Galaxy
The Owl Nebula, Messier 97, a planetary nebula in our galaxy, and the edge-on spiral galaxy Messier 108, paired below the Bowl of the Big Dipper in Ursa Major. This is a stack of 5 x 4-minute exposures at ISO 1600 with the Nikon Z6 taken as part of testing. This was through the Astro-Physics Traveler refractor at f/6 with the Hotech field flattener and FTZ adapter.

For any owner of a Nikon cropped-frame DSLR (from the 3000, 5000, or 7000 series for example) wanting to upgrade to full-frame for astrophotography I would suggest moving to the Z6 over choosing a current DSLR. 

Mirrorless is the way of the future. And the Z6 will yield lower noise than most, if not all, of Nikon’s cropped-frame cameras.

Nikkor 35mm S Lens copy
The Z6 with the Nikkor 35mm f/1.8 S lens native for the Z mount.

For owners of current Nikon DSLRs, especially a 24-megapixel camera such as the D750, moving to a Z6 will not provide a significant improvement in image quality for still images. 

But … it will provide 4K video and much better low-light video performance than older DSLRs. So if it is aurora videos you are after, the Z6 will work well, though not quite as well as a Sony alpha. 

In all, there’s little downside to the Z6 for astrophotography, and some significant advantages: low noise, bright live view, clean artifact-free sensor images, touchscreen convenience, silent shooting, low-light 4K video, all in a lighter weight body than most full-frame DSLRs. 

I highly recommend the Nikon Z6. 

— Alan, April 30, 2019 / © 2019 Alan Dyer / AmazingSky.com 

 

 

Testing the Venus Optics 15mm Lens


Laowa Test Title

I test out a fast and very wide lens designed specifically for Sony mirrorless cameras. 

In a previous test I presented results on how well the Sony a7III mirrorless camera performs for nightscape and deep-sky photography. It works very well indeed.

But what about lenses for the Sony? Here’s one ideal for astrophotography.


TL;DR Conclusions

Made for Sony e-mount cameras, the Venus Optics 15mm f/2 Laowa provides excellent on- and off-axis performance in a fast and compact lens ideal for nightscape, time-lapse, and wide-field tracked astrophotography with Sony mirrorless cameras. (UPDATE: Venus Optics has announced versions of this lens for Canon R and Nikon Z mount mirrorless cameras.)

I use it a lot and highly recommend it.


Size and Weight

While I often use the a7III with my Canon lenses by way of a Metabones adapter, the Sony really comes into its own when matched to a “native” lens made for the Sony e-mount. The selection of fast, wide lenses from Sony itself is limited, with the new Sony 24mm G-Master a popular favourite (I have yet to try it).

However, for much of my nightscape shooting, and certainly for auroras, I prefer lenses even wider than 24mm, and the faster the better.

Auroral Swirls over Båtsfjord, Norway Aurora over Båtsfjord, Norway. This is a single 0.8-second exposure at f/2 with the 15mm Venus Optics lens and Sony a7III at ISO 1600.

The Laowa 15mm f/2 from Venus Optics fills the bill very nicely, providing excellent speed in a compact lens. While wide, the Laowa is a rectilinear lens providing straight horizons even when aimed up, as shown above. This is not a fish-eye lens.

Laowa 15mm Front View with Filter Though a very wide lens, the 15mm Laowa accepts standard 72mm filters. The metal lens hood is removable. © 2019 Alan Dyer

The Venus Optics 15mm realizes the potential of mirrorless cameras and their short flange distance that allows the design of fast, wide lenses without massive bulk.

Sigma 14mm vs Laowa 15mm Sigma 14mm f/1.8 Art lens (for Nikon mount) vs. Venus Optics 15mm f/2 lens (for Sony mount). © 2019 Alan Dyer

While compact, at 600 grams the Laowa 15mm is quite hefty for its size due to its solid metal construction. Nevertheless, it is half the weight of the massive 1250-gram Sigma 14mm f/1.8 Art. The Laowa is not a plastic entry-level lens, nor is it cheap, at $850 from U.S. sources.

For me, the Sony-Laowa combination is my first choice for a lightweight travel camera for overseas aurora trips

Laowa 15mm Back View The lens mount showing no electrical contacts to transfer lens metadata to the camera. © 2019 Alan Dyer

However, this is a no-frills manual focus lens. Nor does it even transfer aperture data to the camera, which is a pity. There are no electrical connections between the lens and camera.

However, for nightscape work where all settings are adjusted manually, the Venus Optics 15mm works just fine. The key factor is how good are the optics. I’m happy to report that they are very good indeed.


Testing Under the Stars

To test the Venus Optics lens I shot “same night” images, all tracked, with the Sigma 14mm f/1.8 Art lens, at left, and the Rokinon 14mm SP (labeled as being f/2.4, at right). Both are much larger lenses, made for DSLRs, with bulbous front elements not able to accept filters. But they are both superb lenses. See my test report on these lenses published in 2018.

Sigma and Rokinon 14mm The Sigma 14mm f/1.8 Art lens (left) vs. the Rokinon SP 14mm f/2.4. © 2019 Alan Dyer

The next images show blow-ups of the same scene (the nightscape shown in full below, taken at Dinosaur Provincial Park, Alberta), and all taken on a tracker.

I used the Rokinon on the Sony a7III using the Metabones adapter which, unlike some brands of lens adapters, does not compromise the optical quality of the lens by shifting its focal position. But lacking a lens adapter for Nikon-to-Sony at the time of testing, I used the Nikon-mount Sigma lens on a Nikon D750, a DSLR camera with nearly identical sensor specs to the Sony.


Vignetting

Laowa 15mm @ f2 A tracked image with the Venus Optics Laowa 15mm at f/2. Click or tap on an image to download a full-resolution JPG for closer inspection.

Above is a tracked image (so the stars are not trailed, which would make it hard to tell aberrations from trails), taken wide open at f/2. No lens correction has been applied so the vignetting (the darkening of the frame corners) is as the lens provides.

As shown above, when used wide open at f/2 vignetting is significant, but not much more so than with competitive lenses with much larger lenses, as I compare below.

And the vignetting is correctable in processing. Adobe Camera Raw and Lightroom have this lens in their lens profile database. That’s not the case with current versions (as of April 2019) of other raw developers such as DxO PhotoLab, ON1 Photo RAW, and Raw Therapee where vignetting corrections have to be dialled in manually by eye.

Laowa 15mm @ f2.8 A tracked image with the Venus Optics Laowa 15mm stopped down 1 stop to f/2.8.

When stopped down to f/2.8 the Laowa “flattens” out a lot for vignetting and uniformity of frame illumination. Corner aberrations also improve but are still present. I show those in close-up detail below.

Lens Comparison - Vignetting 15mm Laowa vs. Rokinon 14mm SP vs. Sigma Art 14mm – Comparing the left side of the image for vignetting (light fall-off), wide open and stopped down. ©2018 Alan Dyer

Above, I compare the vignetting of the three lenses, both wide open and when stopped down. Wide open, all the lenses, even the Sigma and Rokinon despite their large front elements, show quite a bit of drop off in illumination at the corners.

The Rokinon SP actually seems to be the worst of the trio, showing some residual vignetting even at f/2.8, while it is reduced significantly in the Laowa and Sigma lenses. Oddly, the Rokinon SP, even though it is labeled as f/2.4, seemed to open to f/2.2, at least as indicated by the aperture metadata.


On-Axis Performance

Lens Comparison - Centre 15mm Laowa vs. Rokinon 14mm SP vs. Sigma Art 14mm – Comparing the centre of the image for sharpness, wide open and stopped down. Click or tap on an image to download a full-resolution JPG for closer inspection. © 2018 Alan Dyer

Above I show lens sharpness on-axis, both wide open and stopped down, to check for spherical and chromatic aberrations with the bright blue star Vega centered. The red box in the Navigator window at top right indicates what portion of the frame I am showing, at 200% magnification in Photoshop.

On-axis, the Venus Optics 15mm shows stars just as sharply as the premium Sigma and Rokinon lenses, with no sign of blurring spherical aberration nor coloured haloes from chromatic aberration.

Laowa 15mm Side with Focus Point This is where this lens reaches sharpest focus on stars, just shy of the Infinity mark. © 2019 Alan Dyer

Focusing is precise and easy to achieve with the Sony on Live View. My unit reaches sharpest focus on stars with the lens set just shy of the middle of the infinity symbol. This  is consistent and allows me to preset focus just by dialing the focus ring, handy for shooting auroras at -35° C, when I prefer to minimize fussing with camera settings, thank you very much!


Off-Axis Performance

Lens Comparison - Upper Left 15mm Laowa vs. Rokinon 14mm SP vs. Sigma Art 14mm – Comparing the centre of the image for sharpness, wide open and stopped down. Click or tap on an image to download a full-resolution JPG for closer inspection. © 2018 Alan Dyer
Lens Comparison - Upper Right 15mm Laowa vs. Rokinon 14mm SP vs. Sigma Art 14mm – Comparing the upper right corner of the image for aberrations, wide open and stopped down. © 2018 Alan Dyer

The Laowa and Sigma lenses show similar levels of off-axis coma and astigmatism, with the Laowa exhibiting slightly more lateral chromatic aberration than the Sigma. Both improve a lot when stopped down one stop, but aberrations are still present though to a lesser degree.

However, I find that the Laowa 15mm performs as well as the Sigma 14mm Art for star quality on- and off-axis. And that’s a high standard to match.

The Rokinon SP is the worst of the trio, showing significant elongation of off-axis star images (they look like lines aimed at the frame centre), likely due to astigmatism. With the 14mm SP, this aberration was still present at f/2.8, and was worse at the upper right corner than at the upper left corner, an indication to me that even the premium Rokinon SP lens exhibits slight lens de-centering, an issue users have often found with other Rokinon lenses.


Real-World Examples – The Milky Way

Sweep of the Autumn Milky Way This is a stack of 8 x 2-minute exposures with the Venus Optics Laowa 15mm lens at f/2 and Sony a7III at ISO 800, on the Sky-Watcher Star Adventurer tracker. A single exposure taken through the Kenko Softon A filter layered in with Lighten mode adds the star glows, though exaggerates the lens distortion on the bright stars.
Mars and the Milky Way over Writing-on-Stone This is a stack of 12 exposures for the ground, mean combined to smooth noise, and one exposure for the sky, all 30 seconds at f/2 with the Laowa 15mm lens on the Sony a7III camera at ISO 6400. These were the last frames in a 340-frame time-lapse sequence.

The fast speed of the Laowa 15mm is ideal for shooting tracked wide-field images of the Milky Way, and untracked camera-on-tripod nightscapes and time-lapses of the Milky Way.

Image aberrations are very acceptable at f/2, a speed that allows shutter speed and ISO to be kept lower for minimal star trailing and noise while ensuring a well-exposed frame.


Real World Examples – Auroras

Coloured Curtains over CNSC (Feb 9, 2019) Aurora over the Churchill Northern Studies Centre, Churchill, Manitoba. This is 6 seconds at f/2 with the 15mm Venus Optic lens and Sony a7III at ISO 3200.
Sky-Filling Aurora at Tibbitt Lake Aurora from near Yellowknife, NWT, September 8, 2018. This is 2.5-seconds at f/2 with the Venus Optics 15mm lens and Sony a7IIII at ISO 3200.
Aurora from at Sea Near Lofotens #1 The Northern Lights from at sea when leaving the Lofoten Islands, Norway heading toward the mainlaind, from Stamsund to Bodo, March 3, 2019. This was from the Hurtigruten ship the ms Trollfjord. This is a single 1-second exposure for at f/2 with the 15mm Venus Optics lens and Sony a7III at ISO 6400.

Where the Laowa 15mm really shines is for auroras. On my trips to chase the Northern Lights I often take nothing but the Sony-Laowa pair, to keep weight and size down.

Above is an example, taken from a moving ship off the coast of Norway. The fast f/2 speed (I wish it were even faster!) makes it possible to capture the Lights in only 1- or 2-second exposures, albeit at ISO 6400. But the fast shutter speed is needed for minimizing ship movement.


Video Links

The Sony also excels at real-time 4K video, able to shoot at ISO 12,800 to 51,200 without excessive noise.

Aurora Reflections from Alan Dyer on Vimeo.

The Sky is Dancing from Alan Dyer on Vimeo.

The Northern Lights At Sea from Alan Dyer on Vimeo.

Examples of my aurora videos shot with the Sony and Venus Optics 15mm lens are in previous blogs from Yellowknife, NWT in September 2018, from Churchill, Manitoba in February 2019, and from at sea in Norway in March 2019.

Click through to see the posts and the videos shot with the Venus Optics 15mm.

As an aid to video use, the aperture ring of the Venus Optics 15mm can be “de-clicked” at the flick of a switch, allowing users to smoothly adjust the iris during shooting, avoiding audible clicks and jumps in brightness. That’s a very nice feature indeed.

In all, I can recommend the Venus Optics Laowa 15mm lens as a great match to Sony mirrorless cameras, for nightscape still and video shooting. UPDATE: Versions for Canon R and Nikon Z mount mirrorless cameras will now be available.

— Alan, April 20, 2019 / © 2019 Alan Dyer / AmazingSky.com

Testing ON1 Photo RAW for Astrophotography


ON1 Testing Title

Can the new version of ON1 Photo RAW match Photoshop for astrophotography? 

The short TL;DR answer: No.

But … as always, it depends. So do read on.


Released in mid-November 2018, the latest version of ON1 Photo RAW greatly improves a non-destructive workflow. Combining Browsing, Cataloging, Raw Developing, with newly improved Layers capabilities, ON1 is out to compete with Adobe’s Creative Cloud photo suite – Lightroom, Camera Raw, Bridge, and Photoshop – for those looking for a non-subscription alternative.

Many reviewers love the new ON1 – for “normal” photography.

But can it replace Adobe for night sky photos? I put ON1 Photo RAW 2019 through its paces for the demanding tasks of processing nightscapes, time-lapses, and deep-sky astrophotos.


The Conclusions

In my eBook “How to Photograph and Process Nightscapes and Time-Lapses” (linked to at right) I present dozens of processing tutorials, including several on how to use ON1 Photo RAW, but the 2018 edition. I was critical of many aspects of the old version, primarily of its destructive workflow when going from its Develop and Effects modules to the limited Layers module of the 2018 edition.

I’m glad to see many of the shortfalls have been addressed, with the 2019 edition offering a much better workflow allowing layering of raw images while maintaining access to all the original raw settings and adjustments. You no longer have to flatten and commit to image settings to layer them for composites. When working with Layers you are no longer locked out of key functions such as cropping.

I won’t detail all the changes to ON1 2019 but they are significant and welcome.

The question I had was: Are they enough for high-quality astrophotos in a non-destructive workflow, Adobe Photoshop’s forté.

While ON1 Photo RAW 2019 is much better, I concluded it still isn’t a full replacement of Adobe’s Creative Cloud suite, as least not for astrophotography.

NOTE: All images can be downloaded as high-res versions for closer inspection. 


ON1 2019 is Better, But for Astrophotography …

  1. Functions in Layers are still limited. For example, there is no stacking and averaging for noise smoothing. Affinity Photo has those.
  2. Filters, though abundant for artistic special effect “looks,” are limited in basic but essential functions. There is no Median filter, for one.
  3. Despite a proliferation of contrast controls, for deep-sky images (nebulas and galaxies) I was still not able to achieve the quality of images I’ve been used to with Photoshop.
  4. The lack of support for third-party plug-ins means ON1 cannot work with essential time-lapse programs such as Timelapse Workflow or LRTimelapse.
ON1 Final Composite
A finished nightscape composite, with stacked exposures for the ground and stacked and tracked exposures for the sky, layered and blended in ON1.

Recommendations

Nightscapes: ON1 Photo RAW 2019 works acceptably well for nightscape still images:

  1. Its improved layering and excellent masking functions are great for blending separate ground and sky images, or for applying masked adjustments to selected areas.

Time-Lapses: ON1 works is just adequate for basic time-lapse processing:

  1. Yes, you can develop one image and apply its settings to hundreds of images in a set, then export them for assembly into a movie. But there is no way to vary those settings over time, as you can by mating Lightroom to LRTimelapse.
  2. As with the 2018 edition, you still cannot copy and paste masked local adjustments from image to image, limiting their use.
  3. Exporting those images is slow.

Deep-Sky: ON1 is not a program I can recommend for deep-sky image processing:

  1. Stars inevitably end up with unsightly sharpening haloes.
  2. De-Bayering artifacts add blocky textures to the sky background.
  3. And all the contrast controls still don’t provide the “snap” and quality I’m used to with Photoshop when working with low-contrast subjects.

Library / Browse Functions

ON1 Browse Module
ON1 cannot catalog or display movie files or Photoshop’s PSB files (but then again with PSBs neither can Lightroom!).

ON1 is sold first and foremost as a replacement for Adobe Lightroom, and to that extent it can work well. Unlike Lightroom, ON1 allows browsing and working on images without having to import them formally into a catalog.

However, you can create a catalog if you wish, one that can be viewed even if the original images are not “on-line.” The mystery seems to be where ON1 puts its catalog file on your hard drive. I was not able to find it, to manually back it up. Other programs, such as Lightroom and Capture One, locate their catalogs out in the open in the Pictures folder.

For those really wanting a divorce from Adobe, ON1 now offers an intelligent AI-based function for importing Lightroom catalogs and transferring all your Lightroom settings you’ve applied to raw files to ON1’s equivalent controls.

However, while ON1 can read Photoshop PSD files, it will flatten them, so you would lose access to all the original image layers.

ON1’s Browse module is good, with many of the same functions as Lightroom, such as “smart collections.” Affinity Photo – perhaps ON1’s closest competitor as a Photoshop replacement – still lacks anything like it.

But I found ON1’s Browse module buggy, often taking a long while to allow access into a folder, presumably while it is rendering image previews.

There are no plug-ins or extensions for exporting directly to or synching to social media and photo sharing sites.


Nightscape Processing – Developing Raw Images

ON1 Before and After Processing
On the left, a raw image as it came out of the camera. On the right, after developing (with Develop and Effects module settings applied) in ON1.

For this test I used the same nightscape image I threw at Adobe competitors a year ago, in a test of a dozen or more raw developers. It is a 2-minute tracked exposure with a Sigma 20mm Art lens at f/2 and Nikon D750 at ISO 1600.

ON1 did a fairly good job. Some of its special effect filters, such a Dynamic Contrast, Glow, and Sunshine, can help bring out the Milky Way, though do add an artistic “look” to an image which you might or might not like.

Below, I compare Adobe Camera Raw (ACR) to ON1. It was tough to get ON1’s image looking the same as ACR’s result, but then again, perhaps that’s not the point. Does it just look good? Yes, it does.

ON1 & ACR Raw Image Comparison
On the left, a single raw image developed with Adobe Camera Raw. On the right, the same image with ON1 and its basic Develop and more advanced Effects settings.

Compared to Adobe Camera Raw, which has a good array of basic settings, ON1 has most of those and more, in the form of many special Effects, with many combined as one-click Presets, as shown below.

ON1 Presets
ON1 offers a huge array of Presets that apply combinations of its filters with one click from the Browse module.

A few presets and individual filters – the aforementioned Dynamic Contrast and Glow – are valuable. However, most of ON1’s filters and presets will not be useful for astrophotography, unless you are after highly artistic and unnatural effects.

Noise Reduction and Lens Correction

ON1 Noise Reduction
On the left, an image in ON1 without any Noise Reduction. On the right, with noise reduction and sharpening (under Details) applied with the settings shown.

Critical to all astrophotography is excellent noise reduction. ON1 does a fine job here, with good smoothing of noise without harming details.

Lens Correction works OK. It detected the 20mm Sigma art lens and automatically applied distortion correction, but not any vignetting (light “fall-off”) correction, perhaps the most important correction in nightscape work. You have to dial this in manually by eye, a major deficiency.

By comparison, ACR applies both distortion and vignetting correction automatically. It also includes settings for many manual lenses that you can select and apply in a click. For example, ACR (and Lightroom) includes settings for popular Rokinon and Venus Optics manual lenses; ON1 does not.

Hot Pixel Removal

Hot Pixel Removal Comparison
On the left, ACR with noise reduction applied (it offers no user-selectable Hot Pixel Removal tool). In the middle, ON1 with Remove Hot Pixels turned on; on the right, with it turned off – showing more hot pixels than ACR does.

I shot the example image on a warm summer night and without using in-camera Long Exposure Noise Reduction (to keep the gap between exposures short when shooting sets of tracked and untracked exposures for later compositing).

However, the penalty for not using LENR to expedite the image taking is a ground filled with hot pixels. While Adobe Camera Raw does have some level of hot pixel removal working “under the hood,” many specks remained.

ON1 showed more hot pixels, until you clicked Remove Hot Pixels, found under Details. As shown at centre above, it did a decent job getting rid of the worst offenders.

But as I’ll show later, the penalty is that stars now look distorted and sometimes double, or you get the outright removal of stars. ON1 doesn’t do a good job distinguishing between true sharp-edged hot pixels and the softer images of stars. Indeed, it tends to over sharpen stars.

A competitor, Capture One 11, does a better job, with an adjustable Single Pixel removal slider, so you can at least select the level of star loss you are willing to tolerate to get rid of hot pixels.

Star Image Quality

ON1 & ACR Star Image Comparison
On the left, a 700% blow-up of the stars in Adobe Camera Raw. On the right, the same image processed in ON1 and exported out as a PSD.

Yes, we are pixel peeping here, but that’s what we do in astrophotography. A lot!

Stars in ON1 don’t look as good as in Camera Raw. Inevitably, as you add contrast enhancements, stars in ON1 start to exhibit dark and unsightly “sharpening haloes” not present in ACR, despite me applying similar levels of sharpening and contrast boosts to each version of the image.

Camera Raw has been accused of producing images that are not as sharp as with other programs such as Capture One and ON1.

There’s a reason. Other programs over-sharpen, and it shows here.

We can get away with it here in wide-field images, but not later with deep-sky close-ups. I don’t like it. And it is unavoidable. The haloes are there, albeit at a low level, even with no sharpening or contrast enhancements applied, and no matter what image profile is selected (I used ON1 Standard throughout).

De-Bayering Artifacts

ON1-Debayer
ON1, with contrast boosts applied but with no sharpening or noise reduction, shows star haloes, while the sky shows a blocky pattern at the pixel level in high ISO shots.
ACR-Debayer
Adobe Camera Raw, with similar settings but also no sharpening or noise reduction, shows a smooth and uniform sky background.

You might have to download and closely inspect these images to see the effect, but ON1’s de-Bayering routine exhibits a cross-hatched blocky pattern at the pixel-peeping level. ACR does not.

I see this same effect with some other raw developers. For example, the free Raw Therapee shows it with many of its choices for de-Bayering algorithms, but not all. Of the more than a dozen raw developers I tested a year ago, ACR and DxO PhotoLab had (and still have) the most artifact-free de-Bayering and smoothest noise reduction

Again, we can get away with some pixel-level artifacts here, but not later, in deep-sky processing.


Nightscape Processing — Layering and Compositing

ON1 Perfect Brush
ON1’s adjustable “Perfect Brush” option for precise masking around edges and objects isn’t quite as effective as Photoshop’s Quick Selection Tool.

Compositing

The 2018 version of ON1 forced you to destructively flatten images when bringing them into the Layers module.

The 2019 version of ON1 improves that. It is now possible to composite several raw files into one image and still retain all the original Develop and Effects settings for non-destructive work.

You can then use a range of masking tools to mask in or out the sky.

For the example above, I have stacked tracked and untracked exposures, and am starting to mask out the trailed stars from the untracked exposure layer.

To do this with Adobe, you would have to open the developed raw files in Photoshop (ideally using “smart objects” to retain the link back to the raw files). But with ON1 we stay within the same program, to retain access to non-destructive settings. Very nice!

To add masks, ON1 2019 does not have the equivalent of Photoshop’s excellent Quick Selection Tool for selecting the sky or ground. It does have a “Perfect Brush” option which uses the tonal value of the pixels below it, rather than detecting edges, to avoid “painting over the lines.”

While the Perfect Brush does a decent job, it still requires a lot of hand painting to create an accurate mask without holes and defects. There is no non-destructive “Select and Mask” refinement option as in Photoshop.

Yes, ON1’s Refine Brush and Chisel Mask tools can help clean up a mask edge but are destructive to the mask. That’s not acceptable to my non-destructive mindset!

Local Adjustments 

ON1 Masking Adjustments
Local Adjustments can be painted in or out with classic and easy-to-adjust and view masks and layers, rather than adjustment pins used by many raw developers such as ACR.

The masking tools are also applicable to adding “Local Adjustments” to any image layer, to brighten or darken regions of an image for example.

These work well and I find them more intuitive than the “pins” ACR uses on raw files, or DxO PhotoLab’s quirky “U-Point” interface.

ON1’s Local Adjustments work more like Photoshop’s Adjustment Layers and are similarly non-destructive. Excellent.

Luminosity Masks

ON1 Luminosity Masking
ON1 has one-click Luminosity masking, an excellent feature.

A very powerful feature of ON1 is its built-in Luminosity masking.

Yes, Camera Raw now has Range Masks, and Photoshop can be used to create luminosity masks, but making Photoshop’s luminosity masks easily adjustable requires purchasing third-party extension panels.

ON1 can create an adjustable and non-destructive luminosity mask on any image or adjustment layer with a click.

While such masks, based on the brightness of areas, aren’t so useful for low-contrast images like the Milky Way scene above, they can be very powerful for merging high-contrast images (though ON1 also has an HDR function not tested here).

Glow Effect
ON1’s handy Orton-style Glow effect, here with a Luminosity mask applied. The mask can be adjusted with the Levels and Window sliders, and applied to a range of colors as well.

ON1 has the advantage here. Its Luminosity masks are a great feature for compositing exposures or for working on regions of bright and dark in an image.

Final Composite

ON1 Final Composite
A finished nightscape composite, with stacked exposures for the ground and stacked and tracked exposures for the sky, layered and blended in ON1.

Here again is the final result, above.

It is not just one image each for the sky and ground, but is instead a stack of four images for each half of the composite, to smooth noise. This form of stacking is somewhat unique to astrophotography, and is commonly used to reduce noise in nightscapes and in deep-sky images, as shown later.

Stacking

ON1-Layer Opacities
This shows an intermediate step in creating the final composite shown above: Four sky layers are stacked, with opacities as shown, which has the effect of smoothing noise. But to continue working on the image requires making a single “New Stamped Layer” out of the group of four – in this case, the sky layers. The same can be done for the four ground layers.

Here I show how you have to stack images in ON1.

Unlike Photoshop and Affinity Photo, ON1 does not have the ability to merge images automatically into a stack and apply a mathematical averaging to the stack, usually a Mean or Median stack mode. The averaging of the image content is what reduces the random noise.

Instead, with ON1 you have perform an “old school” method of average stacking – by changing the opacity of the layers, so that Layer 2 = 50%, Layer 3 = 33%, Layer 4 = 25%, and so on. The result is identical to performing a Mean stack mode in Photoshop or Affinity.

Fine, except there is no way to perform a Median stack, which can be helpful for eliminating odd elements present in only one frame, perhaps an aircraft trail.

Copy and Paste Settings

ON1 Pasting Settings
ON1 allows easy copying and pasting of settings from one raw image to others, with the annoying exception of Local Adjustments and their masks.

Before we even get to the stacking stage, we have to develop and process all the images in a set. Unlike Lightroom or Camera Raw, ON1 can’t develop and synchronize settings to a set of images at once. You can work on only one image at a time.

So, you work on one image (one of the sky images here), then Copy and Paste its settings to the other images in the set. I show the Paste dialog box here.

This works OK, though I did find some bugs – the masks for some global Effects layers did not copy properly; they copied inverted, as black instead of white masks.

However, Luminosity masks did copy from image to image, which is surprising considering the next point.

The greater limitation is that no Local Adjustments (ones with masks to paint in a correction to a selected area) copy from one image to another … except ones with gradient masks. Why the restriction?

So as wonderful as ON1’s masking tools might be, they aren’t of any use if you want to copy their masked adjustments across several images, or, as shown next, to a large time-lapse set.

While Camera Raw’s and Lightroom’s Local Adjustment pins are more awkward to work with, they do copy across as many images as you like.


Time-Lapse Processing

ON1 Copy & Paste
ON1 does allow developing one image in a set, then copying and pasting its settings to perhaps hundreds of other images in a time-lapse set.

A few Adobe competitors, such as Affinity Photo (as of this writing) simply can’t do this.

By comparison, with the exception of Local Adjustments, ON1 does have good functions for Copying and Pasting Settings. These are essential for processing a set of hundreds of time-lapse frames.

ON1 Export
This is ON1’s Export dialog box, set up here to export the developed raw files into another “intermediate” set of 4K-sized JPGs for movie assembly.

Once all the images are processed – whether it be with ON1 or any other program – the frames have to exported out to an intermediate set of JPGs for assembly into a movie by third-party software. ON1 itself can’t assemble movies, but then again neither can Lightroom (as least not very well), though Photoshop can, through its video editing functions.

For my test set of 220 frames, each with several masked Effects layers, ON1 took 2 hours and 40 minutes to perform the export to 4K JPGs. Photoshop, through its Image Processor utility, took 1 hour and 30 minutes to export the same set, developed similarly and with several local adjustment pins.

ON1 did the job but was slow.

A greater limitation is that, unlike Lightroom, ON1 does not accept any third party plug-ins (it serves as a plug-in for other programs). That means ON1 is not compatible with what I feel are essential programs for advanced time-lapse processing: either Timelapse Workflow (from https://www.timelapseworkflow.com) or the industry-standard LRTimelapse (from https://lrtimelapse.com).

Both programs work with Lightroom to perform incremental adjustments to settings over a set of images, based on the settings of several keyframes.

Lacking the ability to work with these programs means ON1 is not a program for serious and professional time-lapse processing.


Deep-Sky Processing

ON1-Tracked Milky Way
A tracked 2-minute exposure of the Cygnus Milky Way, with a Sony a7III camera at ISO 800 and Venus Optics Laowa 15mm lens at f/2, developed in ON1.
ACR-Tracked Milky Way
The same Milky Way image developed in Adobe Camera Raw. It looks better!

Wide-Angle Milky Way

Now we come to the most demanding task: processing long exposures of the deep-sky, such as wide-angle Milky Way shots and close-ups of nebulas and galaxies taken through telescopes. All require applying generous levels of contrast enhancement.

As the above example shows, try as I might, I could not get my test image of the Milky Way to look as good with ON1 as it did with Adobe Camera Raw. Despite the many ways to increase contrast in ON1 (Contrast, Midtones, Curves, Structure, Haze, Dynamic Contrast and more!), the result still looked flat and with more prominent sky gradients than with ACR.

And remember, with ACR that’s just the start of a processing workflow. You can then take the developed raw file into Photoshop for even more precise work.

With ON1, its effects and filters all you have to work with. Yes, that simplifies the workflow, but its choices are more limited than with Photoshop, despite ON1’s huge number of Presets.

Deep-Sky Close-Ups

ON1 Processed M31
The Andromeda Galaxy, in a stack of six tracked and auto-guided 8-minute exposures with a stock Canon 6D MkII through an 80mm f/6 refractor.
Photoshop Processed M31
The same set of six exposures, stacked and processed with ACR and Photoshop, with multiple masked adjustment layers as at right. The result looks better.

Similarly, taking a popular deep-sky subject, the Andromeda Galaxy, aka M31, and processing the same original images with ON1 and ACR/Photoshop resulted in what I think is a better-looking result with Photoshop.

Of course, it’s possible to change the look of such highly processed images with the application of various Curves and masked adjustment layers. And I’m more expert with Photoshop than with ON1.

But … as with the Cygnus Milky Way image, I just couldn’t get Andromeda looking as good in ON1. It always looked a little flat.

Dynamic Contrast did help snap up the galaxy’s dark lanes, but at the cost of “crunchy” stars, as I show next. A luminosity “star mask” might help protect the stars, but I think the background sky will inevitably suffer from the de-Bayering artifacts.

Star and Background Sky Image Quality

ON1 Processed M31-Close-Up
A 400% close-up of the final Andromeda Galaxy image. It shows haloed stars and a textured and noisy sky background.
Photoshop Processed M31-Close-Up
The same area blown up 400% of the Photoshop version of the Andromeda Galaxy image. Stars and sky look smoother and more natural.

As I showed with the nightscape image, stars in ON1 end up looking too “crunchy,” with dark halos from over sharpening, and also with the blocky de-Bayering artifacts now showing up in the sky.

I feel it is not possible to avoid dark star haloes, as any application of contrast enhancements, so essential for these types of objects, brings them out, even if you back off sharpening at the raw development stage, or apply star masks.

ON1 Processed M31-With & Without
On the left, the image before any processing applied; on the right, after the level of processing needed for such deep-sky images. What starts out looking OK, turns messy.

ON1 is applying too much sharpening “under the hood.” That might “wow” casual daytime photographers into thinking ON1 is making their photos look better, but it is detrimental to deep-sky images. Star haloes are a sign of poor processing.

Noise and Hot Pixels

ON1 With & Without NR and Hot Pixels
With and without noise reduction and hot pixel removal shows stars becoming lost and misshapen with the Remove Hot Pixel option.

ON1’s noise reduction is quite good, and by itself does little harm to image details.

But turn on the Remove Hot Pixel button and stars start to be eaten. Faint stars fade out and brighter stars get distorted into double shapes or have holes in them.

Hot pixel removal is a nice option to have, but for these types of images it does too much harm to be useful. Use LENR or take dark frames, best practices in any case.

Image Alignment and Registration

ON1 Auto-Alignment
The six Andromeda images stacked then “Auto-Aligned” in ON1, with just the top (first) and bottom (last) images turned on here. with the top image switched to Difference blend mode to show any mis-alignment.
Photoshop Auto-Alignment
The same set stacked and “Auto-Aligned” in Photoshop, with the same first and last images turned on and blended with Difference. PS’s alignment is much better, indicated by the image “blacking out” as the two registered frames cancel out.

Before any processing of deep-sky images is possible, it is first necessary to stack and align them, to make up for slight shifts from image to image, usually due to the mount not being perfectly polar aligned. Such shifts can be both translational (left-right, up-down) and rotational (turning about the guide star).

New to ON1 2019 is an Auto-Align Layers function. It worked OK but not nearly as well as Photoshop’s routine. In my test images of M31, ON1 didn’t perform enough rotation.

Once stacked and aligned, and as I showed above, you then have to manually change the opacities of each layer to blend them for noise smoothing.

By comparison, Photoshop has a wonderful Statistics script (under File>Scripts) that will automatically stack, align, then mean or median average the images, and turn the result into a non-destructive smart object, all in one fell swoop. I use it all the time for deep-sky images. There’s no need for separate programs such as Deep-Sky Stacker.

In ON1, however, all that has to be done manually, step-by-step. ON1 does do the job, just not as well.


Wrap-Up

M31 from ON1
The final M31, Andromeda Galaxy image processed with ON1.

ON1 Photo RAW 2019 is a major improvement, primarily in providing a more seamless and less destructive workflow.

Think of it as Lightroom with Layers! 

But it isn’t Photoshop.

Dynamic Contrast
ON1’s useful Dynamic Contrast filter. A little goes a long way.

True to ON1’s heritage as a special effect plug-in, it has some fine Effect filters, such as Dynamic Contrast above, ones I sometimes use from within Photoshop as plug-in smart filters.

Under Sharpen, ON1 does offer a High Pass option, a popular method for sharpening deep-sky objects.

Missing Filters and Adjustments

But for astrophoto use, ON1 is missing a lot of basic but essential filters for pixel-level touch-ups. Here’s a short list:

• Missing are Median, Dust & Scratches, Radial Blur, Shake Reduction, and Smart Sharpen, just to mention a handful of filters I find useful for astrophotography, among the dozens of others Photoshop has, but ON1 does not. But then again, neither does Lightroom, another example of how ON1 is more light Lightroom with layers and not Photoshop.

ON1 Color Adjustment
ON1’s selective Color Adjustment. OK, but where’s the Black and Neutrals?

• While ON1 has many basic adjustments for color and contrast, its version of Photoshop’s Selective Color lacks Neutral or Black sliders, great for making fine changes to color balance in astrophotos.

• While there is a Curves panel, it has no equivalent to Photoshop’s “Targeted Adjustment Tool” for clicking on a region of an image to automatically add an inflection point at the right spot on the curve. This is immensely useful for deep-sky images.

• Also lacking is a basic Levels adjustment. I can live without it, but most astrophotographers would find this a deal-breaker.

• On the other hand, hard-core deep-sky photographers who do most of their processing in specialized programs such as PixInsight, using Photoshop or Lightroom only to perform final touch-ups, might find ON1 perfectly fine. Try it!

Saving and Exporting

ON1 saves its layered images as proprietary .onphoto files and does so automatically. There is no Save command, only a final Export command. As such it is possible to make changes you then decide you don’t like … but too late! The image has already been saved, writing over your earlier good version. Nor can you Save As … a file name of your choice. Annoying!

Opening a layered .onphoto file (even with ON1 itself already open) can take a minute or more for it to render and become editable.

Once you are happy with an image, you can Export the final .onphoto version as a layered .PSD file but the masks ON1 exports to the Photoshop layers may not match the ones you had back in ON1 for opacity. So the exported .PSD file doesn’t look like what you were working on. That’s a bug.

Only exporting a flattened TIFF file gets you a result that matches your ON1 file, but it is now flattened.

Bugs and Cost

I encountered a number of other bugs, ones bad enough to lock up ON1 now and then. I’ve even seen ON1’s own gurus encounter bugs with masking during their live tutorials. These will no doubt get fixed in 2019.x upgrades over the next few months.

But by late 2019 we will no doubt be offered ON1 Photo RAW 2020 for another $80 upgrade fee, over the original $100 to $120 purchase price. True, there’s no subscription, but ON1 still costs a modest annual fee, presuming you want the latest features.

Now, I have absolutely no problem with that, and ON1 2019 is a significant improvement.

However, I found that for astrophotography it still isn’t there yet as a complete replacement for Adobe.

But don’t take my word for it. Download the trial copy and test it for yourself.

— Alan, November 22, 2018 / © 2018 Alan Dyer/AmazingSky.com 

 

Banff by Night


Milky Way Reflections at Bow Lake

Three perfect nights in July provided opportunities to capture the night sky at popular sites in Banff National Park.

When the weather forecast in mid-July looked so promising I made an impromptu trip to Banff to shoot nightscapes and time-lapses under unusually clear skies. Clouds are often the norm in the mountains or, increasingly these days, forest fire smoke in late summer.

But from July 15 to 17 the skies could not have been clearer, except for the clouds that rolled in late on my last night, when I was happy to pack up and get some sleep.

Conjunction over the Continental Divide with Train

My first priority was to shoot the marvellous close conjunction of the Moon and Venus on July 15. I did so from the Storm Mountain viewpoint on the Bow Valley Parkway, with a cooperative train also coming through the scene at the right time.

The Milky Way and Mars over Storm Mountain

This was the view later with the Milky Way and Mars over Bow Valley and Storm Mountain.

Bow Lake by Night Panorama

The next night, July 16, was one of the most perfect I had ever seen in the Rockies. Crystal clear skies, calm winds, and great lake reflections made for a picture-perfect night at Bow Lake on the Icefields Parkway. Above is a 360° panorama shot toward the end of the night when the galactic centre of the Milky Way was over Bow Glacier.

Streaks of green airglow arc across the south, while to the north the sky is purple from a faint display of aurora.

Earlier that night the usual auroral arc known as Steve put in an unexpected appearance. It was just a grey band to the eye, but the camera picked up Steve’s usual pink colours. Another photographer from the U.S. who showed up had no idea there was an aurora happening until I pointed it out.

Mars and the Milky Way at Herbert Lake

My last night was at Herbert Lake, a small pond great for capturing reflections of the mountains around Lake Louise, and the Milky Way. Here, brilliant Mars, so photogenic this summer, also reflects in the still waters.

At each site I shot time-lapses, and used those frames to have some fun with star trail stacking, showing the stars turning from east to west and reflected in the lake waters, and with a single still image taken at the end of the sequence layered in to show the untrailed sky and Milky Way.

But I also turned those frames into time-lapse movies, and incorporated them into a new music video, along with some favourite older clips reprocessed for this new video.

Banff by Night (4K) from Alan Dyer on Vimeo.

Enjoy! And do enlarge to full screen. The video is also in 4K resolution.

Clear skies!

— Alan, August 2, 2018 / © 2018 Alan Dyer / AmazingSky.com

 

Moonlight in the Badlands


Stars over Sedimentary Layers

Clear nights and a waxing Moon made for great opportunities to shoot the Badlands under moonlight.

This has not been a great spring. Only now is the last of the snow melting here in Alberta.

But some mild and clear nights this week with the waxing gibbous Moon allowed me to head to the Red Deer River valley near where I live in Alberta for some moonlit nightscapes.

 

Big Dipper over the Badlands

Here’s the Big Dipper high overhead as it is in spring pointing down to Polaris.

I shot this and some other images in this gallery with the new Sony a7III mirrorless camera. A full test of its astrophoto abilities is in the works.

Jupiter Rising over Red Deer River Badlands

This is Jupiter rising, with the Moon lighting the sky, and illuminating the landscape. Moonlight is the same colour as sunlight, just much fainter. So while this might look like a daytime scene, it isn’t.

Venus in Twilight at the Hoodoos

This is Venus setting in the evening twilight at the Hoodoos on Highway 10 near Drumheller. The winter stars are setting into the west, to disappear for a few months.

Venus, Pleiades and Hyades in Twilight

Here’s Venus in closeup, passing between the Hyades and Pleiades star clusters in Taurus, low in the twilight over the scenic Horsethief Canyon area of the Red Deer River.

While Venus is climbing higher into our evening sky this spring, the Pleiades, Hyades and all the winter stars are fast disappearing from view.

We say goodbye to winter, and not a moment too soon!

— Alan, April 28, 2018 / © 2018 Alan Dyer / AmazingSky.com

 

The Beauty of the Milky Way


Beauty of Milky Way Title

I present a new 4-minute music video (in 4K resolution) featuring time-lapses of the Milky Way.

One of the most amazing sights is the Milky Way slowly moving across the sky. From Canada we see the brightest part of the Milky Way, its core region in Sagittarius and Scorpius moving across the souther horizon in summer.

But from the southern hemisphere, the galactic core rises dramatically and climbs directly overhead, providing a jaw-dropping view of our edge-on Galaxy stretching across the sky. It is a sight all stargazers should see.

I shot the time-lapses from Alberta, Canada and from Australia, mostly in 2016 and 2017.

I include a still-image mosaic of the Milky Way from Aquila to Crux shot in Chile in 2011.

Do watch in 4K if you can! And in Full-Screen mode.

Locations include Writing-on-Stone and Police Outpost Provincial Parks, and Banff and Jasper National Parks in Alberta.

In Australia I shot from the Victoria coast and from inland in New South Wales near Coonabarabran, with some scenes from the annual OzSky Star Safari held each April.

I used a SYRP Genie Mini and a Star Adventurer Mini for the panning sequences, and a TimeLapse+ View intervalometer for the day-to-night sequences.

I processed all sequences (some 7500 frames in total) through the software LRTimelapse to smooth transitions and flickering.

Music is by Audiomachine.

Enjoy!

— Alan, January 22, 2018 / © 2018 Alan Dyer / amazingsky.com 

 

The Fast 14s Face-Off


Sigma and Rokinon 14mm on Stars

I put two new fast 14mm lenses to the test: the Sigma 14mm f/1.8 Art vs. the Rokinon 14mm f/2.4 SP. 

Much to the delight of nightscape and astrophotographers everywhere we have a great selection of new and fast wide-angle lenses to pick from.

Introduced in 2017 are two fast ultra-wide 14mm lenses, from Sigma and from Rokinon/Samyang. Both are rectilinear, not fish-eye, lenses.

I tested the Nikon version of the Sigma 14mm f/1.8 Art lens vs. the Canon version of the Rokinon 14mm f/2.4 SP. I used a Nikon D750 and Canon 6D MkII camera.

I also tested the new faster Rokinon SP against the older and still available Rokinon 14mm f/2.8, long a popular lens among nightscape photographers.

The Sigma 14mm is a fully automatic lens with auto focus. It is the latest in their highly regarded Art series of premium lenses. I have their 20mm and 24mm Art lenses and love them.

The Rokinon 14mm SP (also sold under the Samyang brand) is a manual focus lens, but with an AE chip so that it communicates with the camera. Adjusting the aperture is done on the camera, not by turning a manual aperture ring, as is the case with many of Rokinon’s lower cost series of manual lenses. The lens aperture is then recorded in each image’s EXIF metadata, an aid to later processing. It is part of Rokinon’s premium “Special Performance” SP series which includes an 85mm f/1.2 lens.

All units I tested were items purchased from stock, and were not supplied by manufacturers as samples for testing. I own these!


CONCLUSIONS

For those with no time to read the full review, here are the key points:

• The Sigma f/1.8 Art exhibits slightly more off-axis aberrations than the Rokinon 14mm SP, even at the same aperture. But aberrations are very well controlled.

• As its key selling point, the Sigma offers another full stop of aperture over the Rokinon SP (f/1.8 vs. f/2.4), making many types of images much more feasible, such as high-cadence aurora time-lapses and fixed-camera stills and time-lapses of a deeper, richer Milky Way.

• The Sigma also has lower levels of vignetting (darkening of the frame corners) than the Rokinon 14mm SP, even at the same apertures.

• Both the Sigma Art and Rokinon SP lenses showed very sharp star images at the centre of the frame.

• Comparing the new premium Rokinon 14mm SP against the older Rokinon 14mm f/2.8 revealed that the new SP model has reduced off-axis aberrations and lower levels of vignetting than the lower-cost f/2.8 model. However, so it should for double the price or more of the original f/2.8 lens.

• The Rokinon 14mm SP is a great choice for deep-sky imaging where optical quality is paramount. The Sigma 14mm Art’s extra speed will be superb for time-lapse imaging where the f/1.8 aperture provides more freedom to use shorter shutter speeds or lower ISO settings.

Though exhibiting the lowest image quality of the three lenses, the original Rokinon 14mm f/2.8 remains a superb value, at its typical price of $350 to $500. For nightscapers on a budget, it’s an excellent choice.

 


TESTING PROCEDURES

For all these tests I placed the camera and lens on a tracking mount, the Sky-Watcher Star Adventurer Mini shown below. This allowed the camera to follow the sky, preventing any star trailing. Any distortions you see are due to the lens, not sky motion.

Sigma on SAM on Stars
Star Adventurer Mini Tracker (with Sigma 14mm on Nikon D750)

As I stopped down the aperture, I lengthened the exposure time to compensate, so all images were equally well exposed.

In developing the Raw files in Adobe Camera Raw, I applied a standard level of Contrast (25) and Clarity (50) boost, and a modest colour correction to neutralize the background sky colour. I also applied a standard level of noise reduction and sharpening.

However, I did not apply any lens corrections that, if applied, would reduce lateral chromatic aberrations and compensate for lens vignetting.

So what you see here is what the lens produced out of the camera, with no corrections. Keep in mind that the vignetting you see can be largely compensated for in Raw development, with the provisos noted below. But I wanted to show how much vignetting each lens exhibited.


OFF-AXIS ABERRATIONS

Stars are the severest test of any lens. Not test charts, not day shots of city skylines. Stars.

The first concern with any fast lens is how sharp the stars are not only in the centre of the frame, but also across the frame to the corners. Every lens design requires manufacturers to make compromises on what lens aberrations they are going to suppress at the expense of other lens characteristics. You can never have it all!

However, for astrophotography we do look for stars to be as pinpoint as possible to the corners, with little coma and astigmatism splaying stars into seagull and comet shapes. Stars should also not become rainbow-coloured blobs from lateral chromatic aberration.

SIGMA 14mm ART

Sigma 14mm Upper L Corner
Sigma 14mm Art – Upper Left Corner Close-up at 5 Apertures
Sigma 14mm Upper R Corner
Sigma 14mm Art – Upper Right Corner Close-up at 5 Apertures

These images show 200% blowups of the two upper corners of the Sigma 14mm Art lens, each at five apertures, from wide open at f/1.8, then stopped down at 1/3rd stop increments to f/2.8. As you would expect, performance improves as you stop down the lens, though some astigmatism and coma are still present at f/2.8.

But even wide open at f/1.8, off-axis aberrations are very well controlled and minimal. You have to zoom up this much to see them.

There was no detectable lateral chromatic aberration.

Aberrations were also equal at each corner, showing good lens centering and tight assembly tolerances.

ROKINON 14mm SP

Rokinon 14mm Upper L Corner
Rokinon 14mm SP at 3 Apertures
Rokinon 14mm Upper R Corner
Rokinon 14mm SP at 3 Apertures

Similarly, these images show 200% blow-ups of the upper corners of the Rokinon SP, at its three widest apertures: f/2.4, f/2.8 and f/3.2.

Star images look tighter and less aberrated in the Rokinon, even when compared at the same apertures.

But images look better on the left side of the frame than on the right, indicating a slight lens de-centering or variation in lens position or figuring, a flaw noted by other users in testing Rokinon lenses. The difference is not great and takes pixel-peeping to see. Nevertheless, it is there, and may vary from unit to unit. This should not be the case with any “premium” lens.

SIGMA vs. ROKINON

Rokinon vs Sigma (Corner Aberrations)
Rokinon vs. Sigma Corner Aberrations Compared

This image shows both lenses in one frame, at the same apertures, for a more direct comparison. The Rokinon SP is better, but of course, doesn’t go to f/1.8 as does the Sigma.


ON-AXIS ABERRATIONS

We don’t want good performance at the corners if it means sacrificing sharp images at the centre of the frame, where other aberrations such as spherical aberration can take their toll and blur images.

These images compare the two lenses in 200% blow-ups of an area in the Cygnus Milky Way that includes the Coathanger star cluster. Both lenses look equally as sharp.

SIGMA 14mm ART

Sigma 14mm Centre
Sigma 14mm Art – Centre of Frame Close-up

Even when wide open at f/1.8 the Sigma Art shows very sharp star images, with little improvement when stopped down. Excellent!

ROKINON 14mm SP

Rokinon 14mm Centre
Rokinon 14mm SP – Centre of Frame Close-up

The same can be said for the Rokinon SP. It performs very well when wide open at f/2.4, with star images as sharp as when stopped down 2/3rds of an f-stop to f/3.2

SIGMA vs. ROKINON

Rokinon vs Sigma (Centre Aberrations)
Sigma vs. Rokinon Centre Sharpness Compared

This image shows both lenses in one frame, but with the Sigma wide open at f/1.8 and stopped down to f/2.8, vs. the Rokinon wide open at f/2.4 and stopped to f/2.8. All look superb.


VIGNETTING

The bane of wide-angle lenses is the light fall-off that is inevitable as lens focal lengths decrease. We’d like this vignetting to be minimal. While it can be corrected for later when developing the Raw files, doing so can raise the visibility of noise and discolouration, such as magenta casts. The less vignetting we have to deal with the better.

As with off-axis aberrations, vignetting decreases as lenses are stopped down. Images become more uniformly illuminated across the frame, with less of a “hot spot” in the centre.

SIGMA 14mm ART

Sigma 14mm Vignetting (5 Apertures)
Sigma 14mm Art – Vignetting Compared at 5 Apertures

This set compares the left edge of the frame in the Sigma SP at five apertures, from f/1.8 to f/2.8. You can see how the image gets brighter and more uniform as the lens is stopped down. (The inset image at upper right show what part of the frame I am zooming into.)

ROKINON 14mm SP

Rokinon 14mm Vignetting (3 Apertures)
Rokinon 14mm SP – Vignetting Compared at 3 Apertures

This similar set compares the frame’s left edge in the Rokinon SP at its three widest apertures, from f/2.4 to f/3.2. Again, vignetting improves but is still present at f/3.2.

SIGMA vs. ROKINON

Rokinon vs Sigma Vignetting
Rokinon vs. Sigma – Vignetting Compared

This compares both lenses at similar apertures side by side for a direct comparison. The Sigma is better than the Rokinon with a much more uniform illumination across the frame.

Sigma 14mm Vignetting at f1.8
Sigma 14mm Art – Vignetting at f/1.8 Maximum Aperture
Rokinon 14mm Vignetting at f2.4
Rokinon 14mm SP – Vignetting at f/2.4 Maximum Aperture

In these two images, above, of the entire frame at their respectively widest apertures, I’d say the Sigma exhibits less vignetting than the Rokinon, even when wide open at f/1.8. The cost for this performance, other than in dollars, is that the Sigma is a large, heavy lens with a massive front lens element.


ROKINON 14mm f/2.4 SP vs. ROKINON 14mm f/2.8 Standard

Even the Rokinon 14mm SP, though a manual lens, carries a premium price, at $800 to $1000 U.S., depending on the lens mount.

Samyang 14mm Lens
The 14mm Rokinon/Samyang f/2.8 Lens

For those looking for a low-cost, ultra-wide lens, the original Rokinon/Samyang 14mm f/2.8 (shown above) is still available and popular. It is a fully manual lens, though versions are available with a AE chip to communicate lens aperture information to the camera.

I happily used this f/2.8 lens for several years. Before I sold it earlier in 2017 (before I acquired the Sigma 14mm), I tested it against Rokinon’s premium SP version.

The older f/2.8 lens exhibited worse off-axis and on-axis aberrations and vignetting than the SP, even with the SP lens set to the same f/2.8 aperture. But image quality of the original lens is still very good, and the price is attractive, at half the price or less, than the 14mm SP Rokinon.

TWO 14mm ROKINONS: OFF-AXIS ABERRATIONS

14mm Rokinons Aberrations (Upper L Corner)
Two Rokinons (Older “Standard” vs. new SP) – Upper Left Corner Close-up
14mm Rokinons Aberrations (Upper R Corner)
Two Rokinons (Older “Standard” vs. new SP) – Upper Right Corner Close-up

Here, in closeups of the upper corners, I show the difference between the two Rokinons, the older standard lens on the left, and the new SP on the right.

The SP, as it should, shows lower aberrations and tighter star images, though with the improvement most marked on the left corner; not so much on the right corner. The original f/2.8 lens holds its own quite well.

TWO 14mm ROKINONS: ON-AXIS ABERRATIONS

14mm Rokinons Aberrations (Centre)
Two Rokinons (Older “Standard” vs. new SP) – Centre of Frame Close-up

At the centre of the frame, the difference is more apparent, with the SP lens exhibiting sharper star images than the old 14mm with its generally softer, larger star images. The latter likely has more spherical aberration.

TWO 14mm ROKINONS: VIGNETTING

14mm Rokinons Vignetting
Two Rokinons (Older “Standard” vs. new SP) – Vignetting Compared

The new SP lens clearly has the advantage here, with less vignetting and brighter corners even when wide open at f/2.4 than the older lens does at its widest aperture of f/2.8. This is another reason to go for the new SP if image quality is paramount


PRICES

The new Sigma 14mm Art lens is costly, at $1600 U.S., though with a price commensurate with its focal length and aperture. Other premium lenses in this focal length range, either prime or zoom, from Nikon and Canon sell for much more, and have only an f/2.8 maximum aperture. So in that sense, the Sigma Art is a bargain.

The new Rokinon 14mm SP sells for $800 to $1000, still a premium price for a manual focus lens. But its optical quality competes with the best.

The older Rokinon 14mm f/2.8 is a fantastic value at $350 to $500, depending on lens mount and AE chip. For anyone getting into nightscape and Milky Way photography, it is a great choice.


RECOMMENDATIONS

With such a huge range in price, what should you buy?

A 14mm is a superb lens for nightscape shooting – for sky-filling auroras, for panoramas along the Milky Way, or of the entire sky. But the lens needs to be fast. All three lenses on offer here satisfy that requirement.

Sigma 14mm & Rokinon 14mm SP (Front)
Sigma 14mm Art (left) and Rokinon 14mm SP (right)

SIGMA 14mm f/1.8 ART

If you want sheer speed, this is the lens. It offers a full stop gain over the already fast Rokinon f/2.5, allowing exposures to be half the length, or shooting at half the ISO speed for less noise.

Its fast speed comes into its own for rapid cadence aurora time-lapses, to freeze auroral motion as much as possible in exposures as short as 1 to 2 seconds at a high ISO. The fast speed might also make real-time movies of the aurora possible on cameras sensitive and noiseless enough to allow video shooting at ISO 25,000 and higher, such as the Sony a7s models.

The Sigma’s fast speed also allows grabbing rich images of the Milky Way in exposures short enough to avoid star trailing, either in still images or in time-lapses of the Milky Way in motion.

While the Sigma does exhibit some edge aberrations, they are very well controlled (much less than I see with some 24mm and 35mm lenses I have) and are a reasonable tradeoff for the speed and low level of vignetting, which results in less noisy corners.

Photographers obsess over corner aberrations when, for fixed-camera nightscape shooting, a low level of vignetting is probably more critical. Correcting excessive vignetting introduces noise, while the corner aberrations may well be masked by star trailing. Only in tracked images do corner aberrations become more visible, as in the test images here.

I’d suggest the Sigma is the best choice for nightscape and time-lapse shooting, with its speed allowing for kinds of shots not possible otherwise.

The Sigma also appears to be the best coated of all the lenses, as you can see in the reflections in the lenses in the opening image, and below. However, I did not test the lenses for flares and ghosting.

As a footnote, none of the lenses allow front-mounted filters, and none have filter drawers.

ROKINON 14mm f/2.4 SP

For less money you get excellent optical quality, though with perhaps some worrisome variation in how well the lens elements are figured or assembled, as evidenced by the inconsistent level of aberration from corner to corner.

Nevertheless, stars are tight on- and off-axis, and vignetting is quite low, for corners that will be less noisy when the shadows are recovered in processing.

I’d suggest the Rokinon SP is a great choice if tracked deep-sky images are your prime interest, where off-axis performance is most visible. However, the SP’s inconsistent aberrations from corner to corner are evidence of lower manufacturing tolerances than Sigma’s, so your unit may not perform like mine.

For nightscape work, the SP’s f/2.4 aperture might seem a minor gain over Rokinon’s lower-cost f/2.8 lens. But it is 1/3 of an f-stop. That means, for example, untracked Milky Way exposures could be 30 seconds instead of 40 seconds, short enough to avoid obvious star trailing. At night, every fraction of an f-stop gain is welcome and significant.

ROKINON 14mm f/2.8 Standard

You might never see the difference in quality between this lens and its premium SP brother in images intended for time-lapse movies, even at 4K resolution.

But those intending to do long-exposure deep-sky imaging, as these test images are, will want the sharpest stars possible across the frame. In which case, consider the 14mm SP.

But if price is a prime consideration, the original f/2.8 Rokinon is a fine choice. You’ll need to apply a fair amount of lens correction in processing, but the lens exists in the Camera Raw/Lightroom database, so correction is just a click away.


Sigma and Rokinon 14mm on Stars

That was a lengthy report, I know! But there’s no point in providing recommendations without the evidence to back them up.

All images, other than the opening “beauty shot,” can be clicked/tapped on to download a full-resolution original JPG for closer inspection.

As I’ve just received the Sigma Art lens I’ve not had a chance to shoot any “real” nightscape images with it yet, just these test shots. But for a real life deep-sky image of the Milky Way shot with the Rokinon SP, see this image from Australia. https://flic.kr/p/SSQm7G

I hope you found the test of value in helping you choose a lens.

Clear skies!

— Alan, September 22, 2017 / © 2017 Alan Dyer / amazingsky.com