Astronomy author and photographer Alan Dyer presents amazing sky sights
Author: Alan Dyer
Alan Dyer, now retired from a career as a writer and producer of science programs for science centres and planetariums, is one of Canada’s best-known astronomy writers. He serves as a contributing editor to SkyNews and Sky and Telescope magazines.
He has co-authored several best selling guidebooks for amateur astronomers, including, with Terence Dickinson, "The Backyard Astronomer’s Guide." He published the multi-media eBook "How to Photograph and Process Nightscapes and Time-Lapses," available on the Apple iBooks Store, Amazon Kindle, and as a PDF set from www.amazingsky.com.
Alan is a member of the exclusive The World at Night photography group (www.twanight.org).
As an amateur astronomer, his interests include astrophotography and deep-sky observing (he compiled some of the popular deep-sky observing lists in the annual RASC Observer's Handbook). Alan takes the opportunity as often as possible to visit the southern hemisphere to pursue both observing and photography under southern skies.
His other obsession, eclipse chasing, has taken him to every continent, chalking up 15 total solar eclipses. Asteroid 78434 is named for him.
To mark the 50th anniversary of Apollo 11, my contribution was to produce a planetarium show about the missions.
I’ve been retired from active planetarium show production and science centre work for more than 5 years now. But it’s great to get back in the Dome now and then.
The opportunity came this summer with the hugely popular 50th anniversary of the first Moon landing by Apollo 11. Everyone was hosting events and parties.
To contribute to the local science centre’s event, TELUS Spark in Calgary kindly gave me the keys to the Evans and Sutherland Digistar planetarium system to produce a special lecture/show for the Dome about the Apollo landings.
It was part of Spark’s well-attended Moon Landing Party night July 20. A collage of iPhone images shows some of the other activities that evening.
It was a capacity crowd, and both my shows were “sold out” with full houses. Indeed, I’m presenting extra shows by popular demand in the coming week so those who couldn’t get tickets on July 20 can see the program.
For you to see the show, and to document it for my posterity, I shot time-lapses of me presenting the show, first in rehearsal with some staff present shot from the audience point of view, then in the first presentation from the stage (my) point of view.
The time-lapses compressed the hour-long show into two 1-minute clips. It really wasn’t that frantic in real life! Here’s the video, from my YouTube channel.
I was impressed and surprised at how popular the Apollo anniversary has been. For most today the Moon landings are old history, before their time. Yet, the Apollo missions continue to inspire and amaze.
Panoramas featuring the arch of the Milky Way have become the icons of dark sky locations. “Panos” can be easy to shoot, but stitching them together can present challenges. Here are my tips and techniques.
My tutorial complements the much more extensive information I provide in my eBook, at right. Here, I’ll step through techniques for simple to more complex panoramas, dealing first with essential shooting methods, then reviewing the workflows I use for processing and stitching panoramas.
What software works best depends on the number of segments in your panorama, or even on the focal length of the lens you used.
PART 1 — SHOOTING
What Equipment Do You Need?
Nightscape panoramas don’t require any more equipment than what you likely already own for shooting the night sky. For Milky Way scenes you need a fast lens and a solid tripod, but any good DSLR or mirrorless camera will suffice.
The tripod head can be either a ball head or a three-axis head, but it should have a horizontal axis marked with a degree scale. This allows you to move the camera at a correct and consistent angle from segment to segment. I think that’s essential.
What you don’t need is a special, and often costly, panorama head. These rotate the camera around the so-called “nodal point” inside the lens, avoiding parallax shifts that can make it difficult to align and stitch adjacent frames. Parallax shift is certainly a concern when shooting interiors or any scenes with prominent content close to the camera. However, in most nightscapes our scene content is far enough away that parallax simply isn’t an issue.
Though not a necessity, I find a levelling base a huge convenience. As I show above, this specialized ball head goes under the usual tripod head and makes it easy to level the main head. It eliminates all the fussing with trial-and-error adjustments of the length of each tripod leg.
Then to level the camera itself, I use the electronic level now in most cameras. Or, if your camera lacks that feature, an accessory bubble level clipped into the camera’s hot shoe will work.
Having the camera level is critical. It can be tipped up, of course, but not tilted left-right. If it isn’t level the whole panorama will be off kilter, requiring excessive straightening and cropping in processing, or the horizon will wave up and down in the final stitch, perhaps causing parts of the scene to go missing.
NOTE: Click or tap on the panorama images to open a high-res version for closer inspection.
Shooting Horizon Panoramas
While panoramas spanning the entire sky might be what you are after, I suggest starting simpler, with panos that take in just a portion of the 360° horizon and only a part of the 180° of the sky. These “partial panos” are great for auroras (above) or noctilucent clouds, (below), or for capturing just the core of the Milky Way over a landscape.
The key to all panorama success is overlap. Segments should overlap by 30 to 50 percent, enabling the stitching software to align the segments using the content common to adjacent frames. Contrary to some users, I’ve never found an issue with having too much overlap, where the same content is present on several frames.
For a practical example, let’s say you shoot with a 24mm lens on a full-frame camera, or a 16mm lens on a cropped-frame camera. Both combinations yield a field of view across the long dimension of the frame of roughly 80°, and across the short dimension of the frame of about 55°.
That means if you shoot with the camera in “landscape” orientation, panning the camera by 40° between segments would provide a generous 50 percent overlap. The left half of each segment will contain the same content as the right half of the previous segment, if you take your panos by turning from left to right.
TIP: My habit is to always shoot from left to right, as that puts the segments in the correct order adjacent to each other when I view them in browser programs such as Lightroom or Adobe Bridge, with images sorted in chronological order (from first to last images in a set) as I typically prefer. But the stitching will work no matter which direction you rotate the camera.
In the example of a 24mm lens and a camera in landscape orientation you could turn at a 45° or 50° spacing and yield enough overlap. However, turning the camera at multiples of 15° is usually the most convenient, as tripod heads are often graduated with markings at 5° increments, and labeled every 15° or 30°.
Some will have coarser and perhaps unlabeled markings. If so, determine what each increment represents, then take care to move the camera consistently by the amount that will provide adequate overlap.
To maximize the coverage of the sky while still framing a good amount of foreground, a common practice is to shoot panoramas with the camera in portrait orientation. That provides more vertical but less horizontal coverage for each frame. In that case, for adequate overlap with a 24mm lens and full-frame camera shoot at 30° spacings.
TIP: When shooting a partial panorama, for example just to the south for the Milky Way, or to the north for the aurora borealis, my practice is to always shoot a segment farther to the left and another to the right of the main scene. Shoot more than you need. Those end segments can get distorted when stitching, but if they don’t contain essential content, they can be cropped out with no loss, leaving your main scene clean and undistorted.
Shooting with a longer lens, such as a 50mm (or 35mm on a cropped frame camera), will yield higher resolution in the final panorama, but you will have much less sky coverage, unless you shoot multiple tiers, as I describe below. You would also have to shoot more segments, at 15° to 20° spacings, taking longer to complete the shoot.
As the number of segments goes up shooting fast becomes more important, to minimize how much the sky moves from segment to segment, and during each exposure itself, to aid in stitching. Remember, the sky appears to be turning from east to west, but the ground isn’t. So a prolonged shoot can cause problems later as the stitching software tries to align on either the fixed ground or the moving stars.
Panoramas on moonlit nights, as I show above, are relatively easy because exposures are short.
Milky Way panoramas taken on dark, moonless nights are tougher. They require fast apertures (f/2 to f/2.8) and high ISOs (ISO 3200 to 6400), to keep individual exposures no more than 30 to 40 seconds long.
Noise lives in the dark foregrounds, so I find it best to err on the side of overexposure, to ensure adequate exposure for the ground, even if it means the sky is bright and the stars slightly trailed. It’s the “Expose to the Right” philosophy I espouse at length in my eBook.
Advanced users can try shooting in two passes: one at a low ISO and with a long exposure for the fixed ground, and another pass at a higher ISO and a shorter exposure for the moving sky. But assembling such a set will take some deft work in Photoshop to align and mask the two stitched panos. None of the examples here are “double exposures.”
Shooting 360° Panoramas
More demanding than partial panoramas are full 360° panoramas, as above. Here I find it is best to start the sequence with the camera aimed toward the celestial pole (to the north in the northern hemisphere, or to the south in the southern hemisphere). That places the area of sky that moves the least over time at the two ends of the panorama, again making it easier for software to align segments, with the two ends taken farthest apart in time meeting up in space.
In our 24mm lens example, to cover the entire 360° scene shooting with a 45° spacing would require at least eight images (8 x 45 = 360). I used 10 above. Using that same lens with the camera in portrait orientation will require at least 12 segments to cover the entire 360° landscape.
Shooting 360° by 180° Panoramas
More demanding still are 360° panoramas that encompass the entire sky, from the ground below the horizon to the zenith overhead. Above is an example.
To do that with a single row of images requires shooting in portrait orientation with a very wide 14mm rectilinear lens on a full-frame camera. That combination has a field of view of about 100° across the long dimension of the sensor.
That sounds generous, but reaching up to the zenith at an altitude of 90° means only a small portion of the landscape will be included along the bottom of the frame.
To provide an even wider field of view to take in more ground, I use full-frame fish-eye lenses on my full-frame cameras, such as Canon’s old 15mm lens (as shown at top) or Rokinon’s 12mm. Even a circular-format fish-eye will work, such as an 8mm on a full-frame camera or 4.5mm on a cropped-frame camera.
All such fish-eye lenses produce curved horizons, but they take in a wide swath of sky, making it possible to include lots of foreground while reaching well past the zenith. Conventional panorama assembly programs won’t work with such wide and distorted segments, but the specialized programs described below will.
Shooting Multi-Tier Panoramas
The alternative technique for “all-sky” panos is to shoot multiple tiers of images: first, a lower row covering the ground and partway up the sky, followed by an upper row completing the coverage of just the sky at top.
The trick is to ensure adequate overlap both horizontally and vertically. With the camera in landscape orientation that will require a 20mm lens for full-frame cameras, or a 14mm lens for cropped-frame cameras. Either combination can cover the entire sky plus lots of foreground in two tiers, though I usually shoot three, just to be sure!.
Shooting with longer lenses provides incredible resolution for billboard-sized “gigapan” blow-ups, but will require shooting three, if not more, tiers, each with many segments. That starts to become a chore to do manually. Some motorized assistance really helps when shooting multi-tier panoramas.
Automating the Pan Shooting
The dedicated pano shooter might want to look at a device such as the GigaPan Epic models or the iOptron iPano, (shown below), all about $800 to $1000.
I’ve tested the latter and it works great. You program in the lens, overlap, and angular sweep desired. The iPano works out how many segments and tiers will be required, and automates the shooting, firing the shutter for the duration you program, then moving to the new position, firing again, and so on. I’ve shot four-tier panos effortlessly and with great success.
However, these devices are generally bigger and heavier than I care to heft around in the field.
Instead, I use the original Genie Mini from SYRP, (below), a $250 device primarily for shooting motion control time-lapses. But the wireless app that programs the Genie also has a panorama function that automatically slews the camera horizontally between exposures, again based on the lens, overlap, and angular sweep you enter. The just-introduced Genie Mini II is similar, but with even more capabilities for camera control.
While combining two Genie Minis allows programming in a vertical motion as well, I’ve been using just a regular tripod head atop the Mini to manually move the camera vertically between each of the horizontal tiers. I don’t feel the one or two moves needed to go from tier to tier too arduous to do manually, and I like to keep my field gear compact and easy to use.
The Genie Mini (now replaced by the Mini II) works great and I highly recommend it, even if panoramas are your only interest. But it is also one of the best, yet most affordable, single-axis motion control devices on the market for time-lapse work.
When to Shoot the Milky Way
While the right gear and techniques are important, go out on the wrong night and you won’t be able to capture the Milky Way as the great sweeping arch you might have hoped for.
In the northern hemisphere the Milky Way arches directly overhead from late July to October for most of the night. That’s fine for spherical fish-eye panoramas, but in rectangular images when the Milky Way is overhead it gets stretched and distorted across the top of the final panorama. For example, in the Bow Lake by Night panorama above, I cropped out most of this distorted content.
The prime season for Milky Way arches is therefore before the Milky Way climbs overhead, while it is still across the eastern sky, as above. That’s on moonless nights from March to early July, with May and June best for catching it in the evening, and not having to wait up until dawn, as is the case in early spring.
TIP: The best way to figure out when and where the Milky Way will appear is to use a desktop planetarium program such as Starry Night or Sky Safari or the free Stellarium. All can realistically depict the Milky Way for your location and date. You can then step through time to see how the Milky Way will move through the night, and how it will frame with your camera and lens combination using the “field of view” indicators the programs provide.
When shooting in the southern hemisphere I like the April to June period for catching the sweep of the southern Milky Way and the galactic core rising in late evening. By contrast, during mid austral winter in July and August the galactic centre shines directly overhead in the evening, a spectacular sight to be sure, but tough to capture in a panorama except in a spherical or fish-eye scene.
That said, I always like to put in a good word for the often sadly neglected winter Milky Way (the summer Milky Way for those “down under”). While lacking the spectacle of the galactic core in Sagittarius, the “other” Milky Way has its attractions such as Orion and Taurus. The best months for a panorama with that Milky Way in an arch across a rectangular frame are January to March. The Zodiacal Light can be a bonus at that season, as it was above.
TIP: Always shoot raw files for the widest dynamic range and flexibility in recovering details in the highlights and shadows. Even so, each segment has to be well exposed and focused out in the field.
And unless you are doing a “two-pass” double exposure, always shoot each segment with identical exposure settings. This is especially critical for bright sky scenes such twilights or moonlit scenes. Vary the exposure and you might get unsightly banding at the seams.
There’s nothing worse than getting home only to find one or more segments was missed, or was out of focus or badly exposed, spoiling the set.
PART 2 — STITCHING
Developing Panorama Segments
Once you have your panorama segments, the next step is to develop and assemble them. For my workflow, the process of assembling a panorama from its constituent segments begins with developing each of those segments identically.
NOTE: Click or tap on the software screen shots to open a high-res version for closer inspection.
I like to develop each segment’s raw file as fully as possible at this first stage in the workflow, applying noise reduction, colour correction, contrast adjustments, shadow and highlight recovery, and any special settings such as dehaze and clarity that can make the Milky Way pop.
I also apply lens corrections to each raw image. While some feel doing so produces problems with stitching later on, I’ve never found that. I prefer to have each frame with minimal vignetting and distortion when going into stitching. I use Adobe Camera Raw out of Adobe Bridge, but Lightroom Classic has identical functions.
There are several other raw developers that can work well at this stage. In other tests I’ve conducted, Capture One and DxO PhotoLab stand out as producing good results on nightscapes. See my blog from 2017 for more on software choices.
The key is developing each raw file identically, usually by working on one segment, then copying and pasting its settings to all the others in a set. Not all raw developers have this “Copy Settings” function. For example, Affinity Photo does not. It works very well as a layer-based editor to replace Photoshop, but is crude in its raw developing “Persona” functions.
While panorama stitching software will apply corrections to smooth out image-to-image variations, I find it is best to ensure all the segments look as similar as possible at the raw stage for brightness, contrast, and colour correction.
Do be aware that among social media groups and chat rooms devoted to nightscape imaging a lot of myth and misinformation abounds about how to process and stitch panoramas, and why some don’t work. Someone having a problem with a particular pano will ask why, and get ten different answers from well-meaning helpers, most of them wrong!
Stitching Simple Panoramas
For example, if your segments don’t join well it likely isn’t because you needed to use a panorama head (one oft-heard bit of advice). I never do. The issue is usually a lack of sufficient overlap. Or perhaps the image content moved too much from frame to frame as the photographer took too long to shoot the set.
Or, even when quickly-shot segments do have lots of overlap, stitching software can still get confused if adjoining segments contain featureless content or content that changes, such as segments over rippling water with no identifiable “landmarks” for the software to latch onto.
The primary problems, however, arise from using software that just isn’t up to the task. Programs that work great on simple panoramas (as the next three examples show) will fail when trying to stitch a more demanding set of segments.
For example, for partial horizon panos shot with 20mm to 50mm lenses, I’ll use the panorama function now built into Adobe Camera Raw (ACR) and Adobe Lightroom Classic, and also in the mobile-friendly Lightroom app. As I show above, ACR can do a wonderful job, yielding a raw DNG file that can continue to be edited non-destructively. It’s by far the easiest and fastest option, and is my first choice.
Another choice, not shown here, is the Photomerge function from within Photoshop, which yields a layered and masked master file, and provides the option for “content-aware” filling of missing areas. It can sometimes work on panos that ACR balks at.
Two programs popular as Adobe alternatives, ON1 PhotoRAW (above) and the aforementioned Affinity Photo (below), also have very capable panorama stitching functions.
However, in testing both programs with the demanding Bow Lake multi-tier panorama I used below with other programs, ON1 2019.5 did an acceptable job, while Affinity 1.7 failed. It works best on simpler panoramas, like this partial scene with a 24mm lens.
Even if they succeed when stitching 360° panoramas, such general-purpose editing programs, Adobe’s included, provide no option for choosing how the final scene gets framed. You have no control over where the program puts the ends of the scene.
Or the program just fails, producing a result like this.
Far worse is that multi-tier panoramas or, as I show above, even single-tier panos shot with very wide lenses, will often completely befuddle your favourite editing software, with it either refusing to perform the stitch or producing bizarre results.
Some photographers attempt to correct such wild distortions with lots of ad hoc adjustments with image-warping filters. But that’s completely unnecessary if you use the right software to begin with.
Stitching Complex Panoramas
When conventional software fails, I turn to the dedicated stitching program PTGui, $150 for MacOS or Windows. The name comes from “Panorama Tools – Graphical User Interface.”
While PTGui can read raw files from most cameras, it will not read any of the development adjustments you made to those files using Lightroom, Camera Raw, or any other raw developers.
So, my workflow is to develop all the raw segments, export them out as 16-bit TIFFs, then import those into PTGui. It can detect what lens was used to take the images, information PTGui needs to stitch accurately. If you used a manual lens you can enter the lens focal length and type (rectilinear or fish-eye) yourself.
I include a full tutorial on using PTGui in my eBook linked to above, but suffice to say that the program usually does a superb job first time and very quickly. You can drag the panorama around to frame the scene as you like, and change the projection at will to create rectangular or spherical format images, as above, and even so-called “little planet” projections that appear as if you were looking down at the scene from space.
Occasionally PTGui complains about some frames, requiring you to manually intervene to pick the same stars or horizon features in adjacent frames to provide enough matching alignment points until it is happy. Its interface also leaves something to be desired, with essential floating windows disappearing behind other mostly blank panels.
When exporting the finished panorama I usually choose to export it as a layered 16-bit Photoshop .PSD or, with big panos, as a Photoshop .PSB “big” document.
The reason is that in aligning the moving stars PTGui (indeed, all programs) can produce a few “fault lines” along the horizon, requiring a manual touch up to the masks to clean up mismatched horizon content, as I show above. Having a layered and masked master makes this easy to do non-destructively, though that’s best done in Photoshop.
However, Affinity Photo (above) can also read layered .PSD and .PSB Photoshop files, preserving the layers. By comparison, ON1 PhotoRAW flattens layered Photoshop files when it imports them, one deficiency that prevents this program from being a true Photoshop alternative.
Once a 360° panorama is in a program like Photoshop, some photographers like to “squish” the panorama horizontally to make it more square, for ease of printing and publication. I prefer not to do that, as it makes the Milky Way look overly tall, distorted, and in my opinion, ugly. But each to their own style.
You can test out a limited trial version of PTGui for free, but I think it is worth the cost as an essential tool for panorama devotees.
Other Stitching Options
However, Windows users can also try Image Composite Editor (ICE), free from Microsoft Research. As shown above in my test 3-tier pano, ICE works very well on complex panoramas, has a clean, user-friendly interface, offers a choice of geometric projections, and can export a master file with each segment on its own layer, if desired, for later editing.
The free, open source program HugIn is based on the same Panorama Tools root software that PTGui uses. However, I find HugIn’s operation clunky and overly technical. Its export process is arcane yet renders out only a flattened image.
In testing it with the same three-tier 21-segment pano that PTGui and ICE handled perfectly, HugIn failed to properly include one segment. However, it is free for MacOS and Windows, and so the price is right and is well worth a try.
With the superb tools now at our disposal, it is possible to create detailed panoramas of the night sky that convey the majesty of the Milky Way – and the night sky – as no single image can. Have fun!
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.
• 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
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
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.
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.
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.
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.
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
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.
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.
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
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.
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
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.
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.
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.
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.
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.
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
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.
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.
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
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
As most cameras do, the Z6 also has a “My Menu” page which you can also populate with favourite menu commands.
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.
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.
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.
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
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.
I was impressed with the Z6.
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.
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.
It was a magical night as the rising Moon lit the Badlands with a golden glow.
When doing nightscape photography it’s often best not to fight the Moon, but to embrace it and use it as your light source.
I did this on a fine night, Easter Sunday, at one of my favourite nightscape spots, Dinosaur Provincial Park.
I set up two cameras to frame different views of the hoodoos as they lit up with the light of the rising waning Moon.
The night started out as a dark moonless evening as twilight ended. Then about 90 minutes after the arrival of darkness, the sky began to brighten again as the Moon rose to illuminate the eroded formations of the Park.
This was a fine example of “bronze hour” illumination, as some have aptly called it.
Photographers know about the “golden hour,” the time just before sunset or just after sunrise when the low Sun lights the landscape with a golden glow.
The Moon does the same thing, with a similar tone, though greatly reduced in intensity.
The low Moon, especially just after Full, casts a yellow or golden tint over the scene. This is caused by our atmosphere absorbing the “cold” blue wavelengths of moonlight, and letting through the “warm” red and yellow tones.
Making use of the rising (or setting) Moon to light a scene is one way to capture a nightscape lit naturally, and not with artificial lights, which are increasingly being frowned upon, if not banned at popular nightscape destinations.
“Bronze hour” lighting is great in still-image nightscapes. But in time-lapses the effect is more striking — indeed, in time-lapse lingo it is called a “moonstrike” scene.
The dark landscape suddenly lights up as if it were dawn, yet stars remain in the sky.
The best nights for such a moonstrike are ones with a waning gibbous or last quarter Moon. At these phases the Moon rises after sunset, to re-light a scene after evening twilight has faded.
On April 21 I made use of such a circumstance to shoot moonstrike stills and movies, not only for their own sake, but for use as illustrations in the next edition of my Nightscapes and Time-lapse eBook (at top here).
One camera, the Nikon D750, I coupled with a device called a bramping intervalometer, in this case the TimeLapse+ View, shown above. It works great to automatically shift the shutter and ISO speeds as the sky darkens then brightens again.
Yes, in bright situations the camera’s own Auto Exposure and Auto ISO modes might accomplish this.
But … once the sky gets dark the Auto circuits fail and you’re left with hugely underexposed images.
The TimeLapse+ View, with its more sensitive built-in light meter, can track right through into full darkness, making it possible to shoot so-called “holy grail” time-lapses that go from daylight to darkness, from sunset to the Milky Way, all shot unattended.
For the other camera, the Sony a7III (with the Laowa 15mm lens I just reviewed) I set the camera manually, then shifted the ISO and shutter speed a couple of times to accommodate the darkening, then brightening of the scene.
Processing the resulting RAW files in the highly-recommended program LRTimelapse smoothed out all the jumps in brightness to make a seamless transition.
I also used the new intervalometer function that Sony has just added to the a7III with its latest firmware update. Hurray! I complained about the lack of an intervalometer in my original review of the Sony a7III. But that’s been fixed.
I shot 425 frames with the Sony, which I not only turned into a movie but, as one can with time-lapse frames, I also stacked into a star trail still image, in this case looking north to the circumpolar stars.
I prefer this action set over dedicated programs such as StarStaX, because it works directly with the developed Raw files. There’s no need to create a set of JPGs to stack, compromising image quality, and departing from the non-destructive workflow I prefer to maintain.
While the still images are very nice, the intended final result was this movie above, a short time-lapse vignette using clips from both cameras. Do watch in HD.
I rendered out the frames from the Sony both as a “normal” time-lapse, and as one with accumulating star trails, again using the Advanced Stacker Plus actions to create the intermediate frames for assembling into the movie.
All these techniques, gear, and apps are explained in tutorials in my eBook, above. However, it’s always great to get a night perfect for putting the methods to work on a real scene.
But what about lenses for the Sony? Here’s one ideal for astrophotography.
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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!
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
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
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.
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.
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.
Spring is the season for Earthshine on the waxing Moon.
April 8 was the perfect night for capturing the waxing crescent Moon illuminated both by the Sun and by the Earth.
The phase was a 4-day-old Moon, old enough to be high in the sky, but young enough – i.e. a thin enough crescent – that its bright side didn’t wash out the dark side!
In the lead photo at top, and even in the single-exposure image below taken earlier in a brighter sky, you can see the night side of the Moon faintly glowing a deep blue, and brighter than the background twilight sky.
This, too, is from sunlight, but light that has bounced off the Earth first to then light up the night side of the Moon.
If you were standing on the lunar surface on the night side, the Sun would be below the horizon but your sky would contain a brilliant blue and almost Full Earth lighting your night, much as the Moon lights our Earthly nights. However, Earth is some 80 times brighter in the Moon’s sky than even the Full Moon is in our sky.
Unlike the single image, the lead image, repeated just above, is a multi-exposure blend (using luminosity masks), to bring out the faint Earthshine and deep blue sky, while retaining details in the bright crescent.
Once the sky gets dark enough to see Earthshine well, no single exposure can record the full range in brightness on both the day and night sides of the Moon.
April 8 was a great night for lunar fans as the crescent Moon also appeared between the two bright star clusters in Taurus, the Hyades and Pleiades, and below reddish Mars.
It was a fine gathering of celestial sights, captured above with a telephoto lens.
This show the chart I used to plan the framing, created with StarryNight™ software and showing the field of the 135mm lens I used.
The chart also shows why spring is best for the waxing Moon. It is at this time of year that the ecliptic – the green line – swings highest into the evening sky, taking the Moon with it, placing it high in the west above obscuring haze.
That makes it easier to see and shoot the subtle Earthshine. And to see sharp details on the Moon.
The 4-day-old waxing crescent Moon on April 8, 2019 exposed for just the bright sunlit crescent, revealing details along the terminator. This is with the 105mm Traveler refractor and 2X AP Barlow lens for an effective focal length of 1200mm at f/12, and with the cropped-frame Canon 60Da at ISO 400, for a single exposure of 1/60 second. This is not a stack or mosaic.
The 4-day-old waxing crescent Moon on April 8, 2019 exposed for just the bright sunlit crescent, revealing details along the terminator. This is with the 105mm Traveler refractor and 2X AP Barlow lens for an effective focal length of 1200mm at f/12, and with the cropped-frame Canon 60Da at ISO 400, for a single exposure of 1/60 second. This is not a stack or mosaic.
After the sky got darker I shot the crescent Moon in a short exposure to capture just the bright crescent, included above in two versions – plain and with labels attached marking the major features visible on a 4-day Moon.
If you missed “Earthshine night” this month, mark May 7 and 8 on your calendar for next month’s opportunities.
There’s a slogan used in the U.S. National Parks that “half the Park is after dark.” It is certainly true at Dinosaur Provincial Park in Alberta.
Last Friday night, March 29, I spent the evening at one of my favourite nightscape sites, Dinosaur Provincial Park, about an hour’s drive east of my home. It was one of those magical nights – clear, mild, dry, and no mosquitoes! Yet!
I wanted to shoot Orion and the photogenic winter sky setting into the evening twilight over the Badlands landscape. This was the last moonless weekend to do so.
I shot some individual images (such as above) and also multi-panel panoramas, created by shooting a series of overlapping images at equal spacings, then stitching them later at the computer.
There’s a narrow window of time between twilight and full darkness when the Milky Way shows up well but the western sky still has a lingering blue glow. This window occurs after the normal “blue hour” favoured by photographers.
The panorama above shows the arch of the winter Milky Way but also the towering band of the Zodiacal Light rising out of the twilight and distant yellow glow of Calgary. Zodiacal Light is sunlight scattering off meteoric and cometary dust orbiting in the inner solar system, so this is a phenomenon in space not in our atmosphere. However, the narrow streak is an aircraft contrail.
Later that night, when the sky was fully dark I shot this complete panorama showing not only the Milky Way and Zodiacal Light to the west, but also the faint arc of the Zodiacal Band continuing on from the pyramid-shaped Zodiacal Light over into the east, where it brightens into the subtle glow of Gegenschein. This is caused by sunlight reflecting off interplanetary dust particles in the direction opposite the Sun.
Both the Band and Gegenschein were visible to the naked eye, but only if you knew what to look for, and have a very dark sky.
A closeup shows the Zodiacal Light in the west as the subtle blue glow tapering toward the top as it meets the Milky Way.
It takes a dark site to see these subtle glows. Dinosaur Park is not an official Dark Sky Preserve but certainly deserves to be. Now if we could only get Calgary, Brooks and Bassano to turn down and shield their lights!
A closeup facing the other way, to the east, shows the area of sky opposite the Milky Way, in the spring sky. The familiar Big Dipper, now high our spring sky, is at top with its handle pointing down to Arcturus and Spica (just rising above the horizon) – remember to “arc to Arcturus, and speed on to Spica.”
Leo is at right of centre, flanked by the Beehive and Coma Berenices star clusters.
Polaris is at left — however, the distortion introduced by the panorama stitching at high altitudes stretches out the sky at the top of the frame, so the Dipper’s Pointer stars do not point in a straight line to Polaris.
The faint Zodiacal Band is visible at right, brightening toward the horizon in the Gegenschein.
I shoot images like these for use as illustrations in future eBook projects about stargazing and the wonders of the night sky. Several are in the works!