It has been many years since we were treated to an aurora as widely seen as the show on May 10, 2024. Here’s my tale of the great display.
As the sky darkened around the world on May 10/11, 2024, sky watchers in both the northern and southern hemispheres were amazed to see the sky lit by the deep reds, greens and pinks of a massive display of aurora. For me, this was my first Kp8 to 9 show (to use one measure of aurora intensity) in more than 20 years, back in the film era!
Throughout the day, aurora chasers’ phones (mine included) had been beeping with alerts of the arrival of a major solar storm, with the usual indicators of auroral activity pinned to the top of the scale.
A NOAA satellite’s eye view of the ring of aurora May 10/11, showing it south of me in Alberta, and across the northern U.S. People in the southern U.S. saw it to their north.
As I show below, the graphic of the intensity of the band of aurora, the auroral oval, was lit up red and wide. This was a night we didn’t have to chase north to see the Northern Lights or aurora borealis — they were coming south to meet us (as I show above).
The Kp Index was reading 9 on SpaceWeatherLiveThe auroral oval was lit up red in the Ovation mapThe 3-hour predictions called for red and magenta alerts!
Observers in the southern hemisphere had the normally elusive aurora australis move much farther north than usual, bringing the Southern Lights even to tropical latitudes in Australia, South America and Africa.
The cause was a massive sunspot group on the Sun which had let off several intense solar flares.
Sunspot group 3664 was so big it could be seen with the naked eye, using solar eclipse glasses. Photo courtesy NASA.
The flares had in turn blown off parts of the Sun’s atmosphere, the corona, that anyone who saw the total eclipse a month earlier had admired so much. But a month later, the corona was being blown our way, in a series of Coronal Mass Ejections (CMEs), to collide with Earth.
A movie of six CMEs blasting toward Earth, captured by the SOHO satellite. Courtesy NASA/ESA.
As it happened I was scheduled to give a community talk in the nearby town early in the evening of May 10, on the topic of The Amazing Sky! Watching the indicators, I could more or less promise the audience that we would indeed see an amazing sky later that evening as it got dark.
Post talk, I hurried home to get the cameras ready, choosing to forgo more hurried driving out to a scenic site in southern Alberta, for the convenience of shooting from my rural backyard. As the sky darkened, the clouds were lit purple, and curtains of aurora appeared in the clear patches.
Clouds and aurora in twilight with the 11mm TTArtisan full-frame fish-eye lens.A bright arc of aurora shining through the purple clouds, with the 7.5mm TTArtisan circular fish-eye lens.
Something big was going on! This was promising to be the best show of Northern Lights I had seen from home in a year (spring 2023 had three great shows at monthly intervals, followed by an aurora drought for many months).
A selfie at the start of the great aurora show of May 10, 2024.
I shot with four cameras (a Canon EOS R, Ra, R5 and R6) — two for time-lapses, one for real-time movies, and one for still images. I used the latter to take many multi-image panoramas, as they are often the best way to capture the wide extent of an aurora across the sky.
The arc of aurora in purple and white across the northern sky from home in Alberta at the start of the great display (about 11:30 p.m. MDT).
Early in the evening the arc of aurora wasn’t the usual green from oxygen, but shades of purple, pink, and even white, likely from sunlit nitrogen. The panorama above is looking north toward a strangely coloured arc of nitrogen (?) aurora.
Then after midnight a more normal curtain appeared suddenly, but toward the south, brightening and rising to engulf much of the southern sky and the sky overhead.
Looking south with the 15mm wide-angle lens.
It is at local midnight to 1 a.m. when substorms usually hit, as we are then looking straight down Earth’s magnetic tail, toward the rain of incoming aurora particles bombarding the Earth. During a substorm, the rain turns into a deluge — the intensity of the incoming electrons increases, sparking a sudden brightening of the aurora, making it dance all the more rapidly.
This is a 300° panorama of my home sky now filled with colourful curtains.
As the aurora explodes in brightness it often swirls up to the zenith (or more correctly, the magnetic zenith) to form one of the sky’s greatest sights, a coronal outburst. Rays and beams converge overhead to form a tunnel effect. It is jaw-dropping.
I’ve seen this many times from northern sites such as Churchill and Yellowknife, where the aurora often dances straight up. And from my latitude of 51° N in western Canada, the aurora does often come down to us.
But this night, people at latitudes where, at best, the aurora might be seen just as a glow on the horizon, saw it dance overhead in a corona show to rival the solar eclipse, and that other corona we saw on April 8!
This is a panorama of a substorm outburst creating an overhead corona with rays converging to the magnetic zenith (south of the true zenith), and amid clouds. The rays show a rich mix of oxygen greens and reds, as well as nitrogen blues blending to create purples. Some greens and reds are mixing to make yellows.
Yes, the long exposures of aurora photos (even those taken with phone cameras) show the colours better than your eye can see them (insensitive as our eyes are to colour in dim light). But this night portions of the arcs and rays were bright enough that greens and pinks were easily visible to the naked eye.
This is a single 9-second exposure of the peak of a bright outburst at 1 a.m. MDT. It was with the Laowa 7.5mm circular fish-eye lens at f/2 on the Canon R5 at ISO 800. It is one frame from a time-lapse sequence. A brief outburst of a substorm created an overhead corona with bright rays converging to the magnetic zenith (south of the true zenith).The corona shows a mix of oxygen greens and reds, as well as nitrogen blues blending to create purples. Some greens and reds mix to make yellows.
At its peak the show was changing rapidly enough, I couldn’t get to all the cameras to aim and frame them, especially the movie camera. The brightest outburst at 1 a.m. lasted just a minute — the time-lapse cameras caught it. The sequence below shows the view in 9-second exposures taken consecutively just 1 second apart.
This series shows a brief outburst of bright aurora at the magnetic zenith overhead. The time between these 7 consecutive 9-second exposures is only 1 second, so this bright outburst did not last long (little more than a minute). With the TTArtisan 7.5mm f/2 fish-eye lens on the Canon R5. Click or tap to enlarge to full screen.
Here’s another sequence of frames taken as part of a time-lapse sequence with the 11mm lens. It shows the change in the aurora over the 80 minutes or so that it was most active for me at my site.
The time between these 12 images is usually 8 minutes, though to include some interesting activity at a bright outburst, the interval is 5 minutes for three of the images around 1 a.m. Each is a 7- or 9-second exposure taken as part of a time-lapse sequence using the 11mm TTArtisan lens at f/2.8 on the Canon R at ISO 800 or 1600.
Shooting time-lapses with fish-eye lenses captures the show with a minimum of attention needed (except to adjust ISO or exposure times when the aurora brightens!). I could use the still camera (with the Laowa 15mm f/2 lens) to take individual shots, such as more selfies and home shots.
This is a single 6-second exposure with the Laowa 15mm lens at f/2 and Canon Ra at ISO 2000.This is a single 4-second exposure with the Laowa 15mm lens at f/2 and Canon Ra at ISO 1600. This is a single 8-second exposure with the Laowa 15mm lens at f/2 on the Canon Ra at ISO 800. Another camera taking a time-lapse is in the scene. I had four going this night.
As colourful as the aurora was at its best between midnight and 1:30 a.m., I think the most unique shots came after the show had subsided to appear just as faint rays across the north again, much as it had begun. To the eye it didn’t look like much, but even on the camera’s live screen I could see unusual colours.
I took more panoramas, to capture one of the most unusual auroral arcs I’ve even seen — a blue and magenta aurora across the north, similar to how the night started.
This a stitch of 11 segments, each 13-second exposures, with the Laowa 15mm lens at f/2 on the Canon Ra camera at ISO 800, and turned to portrait orientation. Processed in Camera Raw and stitched with PTGui.
The colours may be from nitrogen glowing, which tends to light up in blues and purples, especially when illuminated by sunlight at high altitudes. At 2 to 2:30 a.m. the Sun might have been illuminating the aurora at a height of 150 to 400 km, and far to the north.
I’d seen blue-topped green auroras before (and there’s a green aurora off to the west at left here). But this was the first time I’d seen an all-blue aurora, no doubt a product of the intense energy flowing in the upper atmosphere this night. And the season and my latitude.
The panorama is a spherical projection spanning 360º, and reaching to the zenith 90° high at centre. This a stitch of 20 segments, each 13-second exposures, with the Laowa 15mm lens at f/2 on the Canon Ra camera at ISO 800, and turned to portrait orientation. Processed in Camera Raw and stitched with PTGui.
The weirdest aurora was at 2:30 a.m., when in addition to the blue rays of nitrogen, an odd white and magenta patch appeared briefly to the south. What was that??
The lesson here? During a bright show do not go back to sleep when things seem to be dying down. Interesting phenomena can appear in the post-storm time, as we’ve learned with STEVE and other odd red arcs and green proton blobs that we aurora photographers have helped document.
I end with a finale music video, mostly made of the time-lapses I shot this night.
Enjoy!
Bring on more aurora shows as the Sun peaks in activity, perhaps this year. But the best shows often occur in the 2 or 3 years after solar max. So we have several more years to look forward to seeing the Lights dance in our skies.
Watch in full screen and in 4K if you can. For all the tech details click through to YouTube and check the description below the video.
I present a two-minute video set to music of the April 8, 2024 total solar eclipse.
In my previous blog Chasing the Cross Continental Eclipse I told the tale of my chase to see the total eclipse of the Sun. I ended up under mostly clear skies in the Eastern Townships of Québec, Canada, not Texas, my original destination.
Here I present the result of shooting with four cameras that afternoon, taking still images, time-lapses, and a 4K movie.
Be sure to watch in 4K!
The site worked out very well, as the lower Sun in eastern Canada lent itself to views framing the eclipse over a landscape below, in this case a very wavy lake. But I was lucky to have open water as other lakes in the area were still frozen.
My post-eclipse selfie at the Lac Brome site in Quebec for the April 8, 2024 total eclipse of the Sun.
As it was, a snow storm a few days earlier left lots of snow in the area to be included in my post-eclipse selfie.
This was only the third total solar eclipse I’ve seen from Canada, after February 26, 1979 from Manitoba, and August 1, 2008 from the air out of Cambridge Bay, Nunavut in the Canadian Arctic. The next total eclipse from Canada passes over my home in Alberta. But it is not until August 22, 2044!
I had always planned to drive to the April 8, 2024 total eclipse of the Sun. But to where? I ended up on the other side of the continent than originally planned.
It is not often the path of the Moon’s shadow crosses your home country, let alone continent. Only once before in recent years, on August 21, 2017, did the narrow shadow path pass near enough to my home in Alberta to allow me to drive to a total eclipse. They almost always require flying.
Packed and ready to hit the highway for a long eclipse trip.
Yes, while I could drive to the April 8, 2024 eclipse, it was going to demand a much longer drive than in 2017. But driving allowed me to take a carload of telescope and camera gear. So that was the plan.
My destination was San Antonio, Texas. That’s where I had made a hotel booking more than a year earlier. The weather prospects in Texas were forecast to be best (at least according to the long-term averages) of any locations along the path in the U.S. or Canada. (I did not want to drive into Mexico.)
Where I was going! Where I ended up going!
On March 30, with some trepidation, I set out down I-15 heading south. I got as far as Great Falls, Montana, my stop for night one. But it was to be a move in the wrong direction.
The forecast for Eclipse Day as of March 30. Blue is bad; white is good!
The various long-range weather models were all agreeing, even 10 days in advance, that Texas (covered in blue above) was looking poor for eclipse day. But eastern Canada looked good! That was the exact opposite of what had been expected.
So on Easter Sunday, I turned around and headed north, crossing back into Canada at a lonely border post in southwest Saskatchewan.
I proceeded east along the TransCanada, Highway 1. I decided against a route across the northern U.S. and around the southern end of Lake Michigan, to avoid severe weather forecast for the middle of the U.S.
One of my daily Facebook travelogue posts with a beer of the day.
Along the way I posted my beer-du-jour travel reports, as above from Day 8, that day from within the shadow path at last!
Our 1979 eclipse group in 1979.The 1979 eclipse site in 2024.The February 26, 1979 eclipse.
I also stopped at the only total eclipse site, of the 16 I had seen previously, I have ever been able to re-visit. On February 26, 1979 I and a small band of friends from Edmonton viewed the mid-winter eclipse (the last one visible from southern Canada) from a median road (Firdale Road as it is now called) on the TransCanada Highway near Carberry, Manitoba. I found the spot again, where I saw (and shot with my Questar telescope) my first total eclipse of the Sun.
However, a day after entering Ontario, the bad weather caught up with me, forcing an extra night north of Lake Superior while the only highway across the region, Highway 17, was cleared of snow and re-opened at Wawa, the usual cross-Canada choke point.
My new destination (after abandoning the site in the Texas Hill Country) was to be southern Ontario.
The weather prediction as of April 5.Southern Québec looking good!
However, as eclipse day approached and the weather predictions became more precise, it was apparent that Ontario would also be under some cloud. Southern Québec was looking better. So the Eastern Townships became my new Plan A site! I was running out of time!
Using the TPE app to check the Sun’s location once on site, the day before the eclipse.
I arrived on site in Québec with only a day to spare to check out the location I had found by exploring Google maps.
With the Sun lower in the mid-afternoon sky in Québec compared to the high-noon Sun in Texas, I decided to shoot a wide-angle scene of the eclipse over a lake, preferably with open water, not ice! That required a site with public parking on an eastern lakeshore.
The Photographer’s Ephemeris (TPE) app to check Sun angles.Zooming in with TPE app for my chosen Lac Brome site. .
The site I found, then checked out on April 7, was on Lac Brome. It proved ideal — except for the thin cloud that was now predicted to drift through during the eclipse.
Sure enough, that’s just what happened. The cloud detracted from the eclipse only in preventing long-exposure images recording the outermost streamers in the Sun’s atmosphere.
A wide-field view of the eclipse of the Sun, taking in the bright planets Jupiter (at top) and Venus (below) that were easily visible to the unaided eye during totality.
I could have sought out clearer skies by going even farther east, but I was in a crunch for time and hotel rooms! As it was I was able to get rooms everywhere I wanted and at normal “non-eclipse” rates!
A panorama of the lakeside parking area at Lac Brome prior to the eclipse. My RAV4 and camera array, pre-eclipse.I shot with 4 cameras at the car and one set up lakeside.
The Lac Brome site filled with cars during the day, with people from Québec and Ontario, but also from Alberta, and from Pennsylvania, Massachusetts and Maine – at least those were the homes of the folks I enjoyed meeting on eclipse day.
Everyone had a great time and had a superb eclipse experience.
The total eclipse of the Sun over the waters of Lac Brome, in the Eastern Townships of Quebec, Canada. The twilight colours come from sunlight from outside the shadow path.
The lunar shadow arrived from the southwest, from the direction of the Sun, appearing as a dark cloud racing toward us. At the end of the eclipse the sky brightened first in that same direction, as the trailing edge of the shadow shot up across the sky. The clouds helped make the shadow edge more visible.
A time-lapse of the arrival and departure of the lunar shadow, made of 1200 frames each 1 second apart.
I shot with five cameras, just as I had done in 2017, possible only because I drove.
The main rig was my faithful Astro-Physics Traveler, a 105mm refractor telescope the company owner designed for his personal use at the 1991 eclipse in Mexico.
My main eclipse rig, with a 60mm visual scope on the 105mm photo scope, on an equatorial tracking mount.
My Traveler, bought in 1992, has lived up to its name, having now been to six central solar eclipses: the annular eclipses of 1994 (Arizona) and 2023 (Utah), and the total eclipses of 1998 (Curaçao), 2012 (Queensland, Australia), 2017 (Idaho), and now 2024 in Québec, Canada. I paired it with the wonderful matching AP400 mount, which I had only just brought back with me the month before from Australia, where it had spent the last two decades.
All the gear worked great. Unlike six months earlier for the October 14, 2023 annular eclipse in Utah, this time I remembered all the cables needed to have the telescope mount track the Sun.
I did mess up on a couple of settings (such as not framing the 4K movie camera as I should have – in pre-eclipse excitement I just forgot to check my chart). But none of the errors were serious.
The eclipse in a blend of two exposures to display all the fiery pink prominences that were visible during totality around the lunar disk in one image, set against the bright inner corona of the Sun with the dark disk of the Moon in silhouette in front of the Sun.
Once started all my cameras, except for the one on the Traveler, ran unattended.
At this eclipse I was determined to get a good look at it through the small visual scope I had piggybacked onto the Traveler photo scope. While I had used a similar rig in 2017, I only thought to look through the visual scope 20 seconds before totality ended.
Not this year.
A telescopic close-up of the eclipsed Sun. Onto the central blend of images for totality I layered in single images of each of the diamond rings before and after totality. They are when the last or first burst of sunlight shines through lunar valleys. The first diamond ring is at top left, the last at bottom right, so time runs from left to right.
I got a great look at the eclipsed Sun, its corona structures, flaming pink prominences, and breakout of the red chromosphere layer just as totality ended. (You can’t easily see the chromosphere at the start of totality as it can be risky looking too soon through optics when the Sun’s blindingly bright photosphere is still in view.)
This is a composite showing the sequence of events surrounding totality, from just before totality (at upper left) to just after totality (at lower right), with totality in the middle. The contact images were taken 0.6 seconds apart.
And yet, as at all eclipses, I found the naked eye view the most compelling. The “black hole” Sun looked huge and unearthly. While I had binoculars handy, the same 12×36 image-stabilized binoculars I bring to most eclipses, I completely forgot to look though them, just as I forget at most eclipses!
This is a composite showing the complete sequence of the April 8, 2024 eclipse of the Sun, from first contact (at upper left) to last contact (at lower right), with totality at mid-eclipse in the middle.
I shot all the images with the Astro-Physics Traveler 105mm refractor at 630mm focal length and f/6, with the Canon R5 at ISO 100. The partial phases are 1/800 or 1/400 second exposures through a Kendrick/Baader solar filter.
Wanting to record the full sequence, I shot the partial phases until the bitter end. But post-eclipse, people came over and had a look through my scope (I think mine was the only telescope on site). We had a great time exchanging impressions. The hand-held phone camera photos people showed me looked fabulous!
I looked for fleeting shadow bands just before and after totality (I laid out a white sheet on the ground for the purpose) but saw none, a negative observation confirmed by a fellow eclipse chaser at the site.
Time-lapse movies of the second and third contact (start and end of totality) diamond rings, shot through the telescope with the Canon R5 in continuous burst mode for hundreds of frames each.
I did two live interviews for CBC Radio, for the Edmonton and Calgary stations, but not until after the eclipse ended. By the time I did those and finished packing away my carload of gear, it was 6:30 p.m., three hours after totality.
I was the last to leave the site, with fishermen now arriving for an evening’s catch.
I was in that shadow as the Space Station flew over. Astronauts saw the elliptical shadow moving over eastern Canada.
The passage of the lunar shadow across the continent, showing where the clouds were. I was under the wispy clouds at upper right in Québec.
I faced no traffic jams heading back to the hotel at Ste. Helen-de-Bagot. I processed and posted one eclipse image that night. And I revised the price (down to $2.99 U.S.) and description of my How to Photograph the Solar Eclipses ebook, as now only the big processing chapter is of any value, post-eclipse. It continues to sell.
This is the waxing crescent Moon on April 10, 2024, two days after it eclipsed the Sun, and with it above the bright planet Jupiter, with it also near Uranus. Below the solar system worlds is the faint Comet 12P/Pons-Brooks, visible here as a fuzzy star with a stubby tail..
On the long drive back to Alberta, with the pressure of having to make time now gone, I spent pleasant evenings stopping to see friends and family on the road home. So I didn’t start work on the complex blends and composite images I show here until I got home a week after the eclipse.
The happy eclipse chaser having bagged his game!
The 17-day-long drive was nearly 9,000 km over 100 hours behind the wheel. Was it worth it? Of course!
Would I do it again? It’s a moot question as none of the upcoming eclipses allows for a cross-continent drive. Except perhaps in July 2028 in Australia. But I suspect just heading inland a day or two over the Great Dividing Range will be enough to get away from winter coastal cloud in New South Wales. (Sydney is in the path, but so is a cottage I rented last month near Coonabarabran for my superb March stay under the southern skies!)
The next total eclipse of the Sun visible from anywhere in Canada will be August 22, 2044. I won’t have to drive anywhere, as it passes right over my house! But I will have to live that long to enjoy a eclipse from my own backyard.
I suspect this was my last chance to see – and drive to – a total eclipse in Canada.
As eclipse day approaches here are some tips and video tutorials from me about how best to capture the total eclipse of April 8, 2024.
There are many ways to capture great images and movies of a total eclipse of the Sun. I outline them all in great detail in my 380-page ebook How to Capture the Solar Eclipses, linked to at right.
Originally published in June 2023, I revised the ebook following the October 14, 2023 annular eclipse of the Sun to include “lessons learned at the eclipse,” and some processing tutorials on assembling annular eclipse composites. I’ve also added new content on using software to control cameras and updated information about solar filters.
Brief Tips and Techniques
The August 21, 2017 total solar eclipse over the Grand Tetons as seen from the Teton Valley in Idaho, near Driggs. With the Canon 6D and 14mm SP Rokinon lens at f/2.5 for 1/10 second at ISO 100.
My breakdown of recommend methods, in order from simplest to most complex, and with increasing demands on your time, is generally this:
Use a Phone Camera for a Movie. While they can be used for a quick handheld grab shot during totality, a better method is to place a phone on a tripod using a clamp of some kind. Then a few minutes before totality aim and frame the scene, with no filter over the camera lens. Start it in movie mode to record video of the eclipse and sky changes, and the excited sounds of your group! Just remember to stop the video shortly after the end of totality and aim the phone away from the Sun. Never leave any unfiltered camera aimed at the Sun for a long time.
Shoot a Wide-Angle Time-Lapse. Using a DSLR or mirrorless camera and a wide-angle lens (it might need to be as wide as a 14mm at sites in Mexico and the southern U.S.) aim and frame the camera to include the Sun and landscape below. Focus the lens! And leave it on manual focus. But put the camera into Auto-Exposure Aperture Priority (Av) with wide-area metering and with it set to underexpose by -1 EV Exposure Compensation. With the camera at ISO 100 or 200, use either its internal intervalometer (if it has one) or an external intervalometer to take frames once per second. Start the sequence with no filter on the lens a few minutes before totality. Let it run on its own until a few minutes after totality. The result is hundreds of frames you can turn into a time-lapse movie of the lunar shadow approaching and receding, and of the changes in sky colours. Or you can extract single frames at key points to process individually, as I did for the image above from August 2017. The advantage, as with the phone camera movie method, is that the camera, once going, requires no further attention. You can enjoy the eclipse!
Shoot a Telephoto Video. Use a 300mm to 500mm lens on a DSLR or mirrorless camera to shoot a real-time close-up video of the eclipse. Start the video a minute or two before totality with the Sun positioned to the left of frame centre and with a solar filter over the lens. Use a slow ISO, the lens wide open (typically f/4 to f/5.6) and the camera on Auto-Exposure Aperture Priority (Av). Just be careful to focus precisely on the filtered Sun before starting the video. Poor focus is what spoils most eclipse images, not poor exposure. Just before totality (about 30 seconds prior to Second Contact) remove the filter. The auto-exposure will compensate and provide a proper exposure for the rest of totality. Just let the camera run and the Sun drift across the frame from left to right. Just remember to replace the filter, or cap the lens, and stop the video shortly (~30 seconds) after totality and Third Contact. The video will capture the diamond rings and a well-exposed corona. Vary the exposure compensation during totality if you wish, but that involves more work at the camera. Otherwise, you can just let the camera run. But, as I illustrate in my ebook, it’s important to plan and place the Sun correctly to begin with (using a planetarium app to plan the sequence), so it does not drift off the frame or close to the edge.
Shoot Telephoto Close-Up Stills. Use the same type of gear to shoot still images. While you could shoot stills on Auto-Exposure, it’s better to shoot still images over a range of exposures, from very short (~1/1000 second) for the diamond rings and prominences, to long (~1 second) for the outer corona. No one exposure can capture all that the eye can see during totality. This takes more work at the camera, and with the camera on a static tripod you might have to re-centre the Sun during totality, another thing to fuss with and where things can go wrong. Using the camera’s Auto-Bracketing mode can help automate the shooting, allowing the camera to automatically shoot a set of 7 to 9 exposures at say, one-stop increments in quick succession with just one press of the shutter button (by using the self-timer set to 2 seconds).
Shoot with a Telescope on a Tracking Mount. Telescopes (I like 60mm- to 100mm-aperture apochromatic refractors) allow longer focal lengths, though I would advise against shooting with any optics longer than 600mm to 800mm, so the image frames the corona well. Use similar settings as above, but with the telescope (or a telephoto lens) on a tracking mount to turn from east to west at the same rate as the sky moves. That will ensure the Sun stays centred on its own, provided you have at least roughly polar aligned the mount. (Set it to your site’s latitude and aim the polar axis as due north as you can determine from compass apps.)
Those are brief summaries of the methods I recommend, as they are ones I’ve used with success in the past and plan to use on April 8. My ebook contains much more information, and answers to most of the “But what about using ….?” questions. And I provide lots of information on what can go wrong! Some learned the hard way over 16 previous total solar eclipses.
Video Tutorials
For a video tutorial, check out the webinar I conducted as part of the Kalamazoo Astronomical Society’s excellent Eclipse Series here on YouTube. It is about a 1-hour presentation, plus with lots of Q&A at the end.
KAS Eclipse Series — Part 1: Shooting
Of course, once you have all your images, you need to process them. My ebook’s biggest chapter (at 80 pages) is the one on processing still images and time-lapses.
So, a month after I presented the above webinar on Shooting, I was back on-line again for a follow-up webinar on Processing. You can view that KAS Eclipse Series tutorial here on YouTube.
KAS Eclipse Series — Part 2: Processing
I cover processing single wide-angle images, a wide-angle time-lapse series, single-image close-ups, and blending multiple exposure composites.
A month later, I presented a further webinar to the Astronomical League as part of their AL Live series, again on shooting the eclipse, but now with an emphasis on techniques amateur astronomers and astrophotographers with typical telescope gear might use.
You can view the AL Live webinar here. My presentation begins at the 44-minute mark.
AL Live Webinar — Scrub ahead to 44 minutes
I emphasized that the kinds of gear astrophotographers use these days with great success on deep-sky objects might not work well for the eclipse. The specialized cameras, and software used to control them, are just not designed for the demands of a total eclipse, where exposures have to range over a wide array of settings and change very quickly. Images have to be taken and recorded in rapid succession.
I suspect a lot of ambitious and overly-confident astrophotographers will come away from the 2024 eclipse disappointed — and what’s worse, without having seen the eclipse because they were too wrapped up looking at laptop screens trying to get their high-tech gear working.
The Checklist page from my eBook
Practice, Practice, Practice
In these webinars and in my ebook, my common theme is the importance of practicing.
Don’t assume something will work. Practice with the gear you intend to use, on the Sun now (with proper filters) and on the Moon. The crescent Moon, with dim Earthshine lighting the lunar night side, is a great practice target because of its wide range of brightness. And it moves like the Sun will, to check maximum exposure times vs. image blurring from motion.
Practice with your tripod or mount aimed to the altitude and location in the sky where the Sun will be from the site you have chosen. Set a tracking mount to the latitude you will be at to be sure it will aim at and track the Sun without issues. Some telescope mounts stop tracking when they reach due south, exactly where the Sun will be at totality from southern sites. That’s a nasty surprise you do not want to encounter on eclipse day.
All this and much more is covered in my ebook, available for Apple Books and as a PDF for all platforms here from my website at https://www.amazingsky.com/EclipseBook
May 10, 1994 Annular Eclipse taken from a site east of Douglas, Arizona showing “reverse” Bailey’s Beads —lunar mountains just touching Sun’s limb 4-inch f/6 apo refractor at f/15 with Barlow lens Ektachrome 100 slide film.
Here’s my preview of some of the best celestial events for 2023. Mine is certainly not an exhaustive list. I’ve picked just one event per month, and I’ve focused on events best for unaided eyes or binoculars, and visible from North America. (So the solar eclipse of April 20 visible from Australia and the South Pacific, and the two minor lunar eclipses this year don’t make the cut!)
Click or tap on any of the illustrations to bring up a full-screen view with more detail and readable labels!
JANUARY
As 2023 opens, Venus is beginning its climb into the evening sky, while Saturn is sinking into the sunset. The two planets pass each other on Sunday, January 22, when they appear just one-third of a degree apart in the twilight. Use binoculars to pick out dimmer Saturn. And look for the thin day-old crescent Moon just over a binocular field below the planet pair.
FEBRUARY
A month later, on Wednesday, February 22, Venus has now ascended higher, preparing to meet up with descending Jupiter. But before they meet, the crescent Moon, with its dark side lit by faint Earthshine, joins the planets in a particularly close conjunction with Jupiter. They will appear about 1° (two Moon diameters) apart, with Venus about a binocular field below.
MARCH
Here’s a date to circle on your calendar. On Wednesday, March 1 the sky’s two brightest planets, Venus and Jupiter, pass within half a degree of each other, in arguably the year’s best conjunction. They’ll be close enough to frame nicely at medium power in a telescope, though the featureless gibbous disk of Venus will appear small, about the third the size of Jupiter’s banded globe. But Venus is by far the brighter of the two worlds.
APRIL
If you want to check Mercury off your sighting list this year, this is a good week to do it. On April 11 Mercury reaches its greatest angle away from the Sun in the evening sky, and for northern hemisphere viewers, is angled at its highest in the western sky. Even so, look just a binocular field above the horizon. While you’re at it, look higher for the fine sight of Venus near the Pleiades star cluster.
MAY
Wednesday, May 17 brings a chance to see the crescent Moon pass in front of Jupiter. But it will be a tricky event to catch. While most of North America and parts of Northern Europe can see the occultation, it occurs in the daytime sky with the Moon only 25° west of the Sun. However, locations along the West Coast of North America can see either the start or end of the occultation in a bright pre-dawn sky. Vancouver, Canada sees Jupiter disappear before sunrise, while Los Angeles – the view shown above – sees Jupiter reappear just before sunrise. Other locations will see a close conjunction of the Moon and Jupiter low in the dawn sky.
JUNE
As June opens we have Venus still shining brightly in the evening below much dimmer Mars, now far from the Earth and tiny in a telescope. But it’ll be worth a look this night even in binoculars as the red planet passes in front of the Beehive star cluster, also known as Messier 44. If you miss June 2, Mars will be close to the Beehive the night before and after.
JULY
Venus has been bright all spring, but on July 7 it officially peaks at its maximum brilliance, reaching a blazing magnitude of -4.7. It reached its greatest angle from the Sun a month earlier on June 4 and is now dropping closer to the Sun each evening. But you still can’t miss it. What you might miss is dim Mars above, now close to the star Regulus in Leo. Mars passes 3/4 of a degree above Regulus on July 9 and 10. You’ll need binoculars to pick out the pairing.
AUGUST
Everyone looks forward to the annual summer stargazing highlight – watching the Perseid meteor shower. This is a good year, with the peak hour of the shower falling in the middle of the night of August 12/13 for North America. That’s a Saturday night! But most importantly, the waning Moon doesn’t rise until the wee hours, as shown here, so its light won’t wash out the meteors. Plan to be at a dark site for an all-night meteor watch.
SEPTEMBER
By September Venus has made the transition into the morning sky and shines at its greatest dawn-sky brilliance on September 19. It will then be joined by Mercury, with the inner planet reaching its greatest angle away from the Sun on September 22 shown here. This is the best morning appearance of Mercury for Northern Hemisphere observers. The view this morning bookends the view five months earlier on April 11. If you are away from urban light pollution, also look for the faint glow of Zodiacal Light in the pre-dawn sky before Mercury rises.
OCTOBER
October is solar eclipse month! On Saturday, October 14 the shadow of the Moon passes across all of North America and most of South America. Everyone on those two continents sees a partial eclipse of the Sun. But those along a narrow path sweeping across the western U.S. and down into Mexico, Central America and across northern South America can see a rare “ring of fire” eclipse as the Moon’s dark disk eclipses the Sun, but isn’t quite large enough to totally cover it. This is an “annular” eclipse. The view above is from Albuquerque, New Mexico, one of the largest U.S. cities in the path of annularity, second only to San Antonio, Texas.
This is the path of annularity across the western U.S. To see the Moon pass centrally across the Sun (the “ring of fire”) you have to be somewhere in that grey path. Outside the path you will see only a partial eclipse of the Sun. For detailed and zoomable eclipse path maps like the one above, please visit EclipseWise.com.
NOVEMBER
Close conjunctions between the crescent Moon and Venus are always notable. Get up early on Thursday, November 9 to see the 26-day-old Moon shining only a degree below Venus. Venus reached its greatest angle away from the Sun on October 23. It is now descending back toward the Sun, but remains high in the morning sky in early November.
DECEMBER
Though it usually puts on a better show than the summer Perseids, the Geminid meteor shower is not as popular because it’s cold! But this is also a good year for the Geminids as it peaks only two days after New Moon. The best night might be Thursday, December 14, but a good number of meteors should be zipping across the sky the night before on December 13, shown here. Start watching at nightfall and go as long as you can in the chill of a December night.
To download my free Amazing Sky 2023 Calendar in PDF format, go to my website at https://www.amazingsky.com/Books The PDF file can be printed out at home or taken to an office supply shop to be printed and bound.
Good luck in your stargazing and clear skies for 2023!
In a detailed technical blog I compare six AI-based noise reduction programs for the demands of astrophotography. Some can work wonders. Others can ruin your image.
Over the last two years we have seen a spate of specialized programs introduced for removing digital noise from photos. The new generation of programs use artificial intelligence (AI), aka machine learning, trained on thousands of images to better distinguish unwanted noise from desirable image content.
At least that’s the promise – and for noisy but normal daytime images they do work very well.
But in astrophotography our main subjects – stars – can look a lot like specks of pixel-level noise. How well can each program reduce noise without eliminating stars or wanted details, or introducing odd artifacts, making images worse.
To find out, I tested six of the new AI-based programs on real-world – or rather “real-sky” – astrophotos. Does one program stand out from the rest for astrophotography?
NOTE: All the images are full-resolution JPGs you can tap or click on to download for detailed inspection. But that does make the blog page slow to load initially. Patience!
TL;DR SUMMARY
The new AI-trained noise reduction programs can indeed eliminate noise better than older non-AI programs, while leaving fine details untouched or even sharpening them.
Of the group tested, the winner for use on just star-filled images is a specialized program for astrophotography, NoiseXTerminator from RC-Astro.
For nightscapes and other images, Topaz DeNoise AI performed well, better than it did in earlier versions that left lots of patchy artifacts, something AI programs can be prone to.
While ON1’s new NoNoise AI 2023 performed fine, it proved slightly worse in some cases than its earlier 2022 version. Its new sharpening routine needs work.
Other new programs, notably Topaz Photo AI and Luminar’s Noiseless AI, also need improvement before they are ready to be used for the rigours of astrophotography.
For reasons explained below, I would not recommend DxO’s PureRAW2. [See below for comments on the newer DxO PureRaw3, which suffers from the same issues.]
The three test images in Adobe Camera Raw showing the Basic settings applied.
METHODOLOGY
As described below, while some of the programs can be used as stand-alone applications, I tested them all as plug-ins for Photoshop, applying each as a smart filter applied to a developed raw file brought into Photoshop as a Camera Raw smart object.
Most of these programs state that better results might be obtainable by using the stand-alone app on original raw files. But for my personal workflow I prefer to develop the raw files with Adobe Camera Raw, then open those into Photoshop for stacking and layering, applying any further noise reduction or sharpening as non-destructive smart filters.
Many astrophotographers also choose to stack unedited original images with specialized stacking software, then apply further noise reduction and editing later in the workflow. So my workflow and test procedures reflect that.
However, the exception is DxO’s PureRAW2. It can work only on raw files as a stand-alone app, or as a plug-in from Adobe Lightroom. It does not work as a Photoshop plug-in. I tested PureRAW2 by dropping raw Canon .CR3 files onto the app, then exporting the results as raw DNG files, but with the same settings applied as with the other raw files. For the nightscape and wide-field images taken with lenses in DxO’s extensive database, I used PureRAW’s lens corrections, not Adobe’s.
As shown above, I chose three representative images:
A nightscape with star trails and a detailed foreground, at ISO 1600.
A wide-field deep-sky image at ISO 1600 with an 85mm lens, with very tiny stars.
A close-up deep-sky image taken with a telescope and at a high ISO of 3200, showing thermal noise hot pixels.
Each is a single image, not a stack of multiple images.
Before applying the noise reduction, the raw files received just basic color corrections and a contrast boost to emphasize noise all the more.
THE CONTENDERS
In the test results for the three images, I show the original raw image, plus a version with noise reduction and sharpening applied using Adobe Camera Raw’s own sliders, with luminance noise at 40, color noise at 25, and sharpening at 25.
I use this as a base comparison, as it has been the noise reduction I have long applied to images. However, ACR’s routine (also found in Adobe Lightroom) has not changed in years. It is good, but it is not AI.
[See below for an April 2023 update with a comparison of Adobe’s new AI Denoise with DxO DeepPrimeXD and Topaz PhotoAI.]
The new smart AI programs should improve upon this. But do they?
PLEASENOTE:
I have refrained from providing prices and explaining buying options, as frankly some can be complex!
For those details and for trial copies, go to the software’s website by clicking on the link in the header product names below.
All programs are available for Windows and MacOS. I tested the latter versions.
I have not provided tutorials on how to use the software; I have just reported on their results. For trouble-shooting their use, please consult the software company in question.
ON1’s main product is the Lightroom/Photoshop alternative program called ON1 Photo RAW, which is updated annually to major new versions. It has full cataloging options like Lightroom and image layering like Photoshop. Its Edit module contains the NoNoise AI routine. But NoNoise AI can be purchased as a stand-alone app that also installs as a plug-in for Lightroom and Photoshop. It’s what I tested here. The latest 2023 version of NoNoise AI added ON1’s new Tack Sharp AI sharpening routine.
Version tested: 17.0.1
Topaz DeNoise AI’s four-pane view to select the best AI model.
This program has proven very popular and has been adopted by many photographers – and astrophotographers – as an essential part of an editing workflow. It performs noise reduction only, offering a choice of five AI models. Auto modes can choose the models and settings for you based on the image content, but you can override those by adjusting the strength, sharpness, and recovery of original detail as desired.
A separate program, Topaz Sharpen AI, is specifically for image sharpening, but I did not test it here. Topaz Gigapixel AI is for image resizing.
Version tested: 3.7.0
Topaz Photo AI’s control interface for its three main functions: noise, sharpening and upscaling.
In 2022 Topaz introduced this new program which incorporates the trio of noise reduction, sharpening and image resizing in one package. Like DeNoise, Sharpen and Gigapixel, Photo AI works as a stand-alone app or as a plug-in for Lightroom and Photoshop. Photo AI’s Autopilot automatically detects and applies what it thinks the image needs. While it is possible to adjust settings, Photo AI offers much less control than DeNoise AI and Topaz’s other single-purpose programs.
As of this writing in November 2022 Photo AI is enjoying almost weekly updates, and seems to be where Topaz is focusing its development and marketing effort. [See below for a test of PhotoAI v1.3.1, current as of April 2023.]
Version tested: 1.0.9
Luminar Neo’s Edit interface with choices of many filters and effects, including Noiseless AI.
Unlike the other noise reduction programs tested here, Luminar Neo from the software company Skylum is a full-featured image editing program, with an emphasis on one-click AI effects. One of those is the new Noiseless AI, available as an extra-cost extension to the main Neo program, either as a one-time purchase or by annual subscription. Noiseless AI cannot be purchased on its own. However, Neo with most of its extensions does work as a plug-in for Lightroom and Photoshop.
Being new, Luminar Neo is also updated frequently, with more extensions coming in the next few months.
Version tested: 1.5.0
DxO PureRAW’s simple interface with few choices for Noise Reduction settings.
Like ON1, DxO makes a full-featured alternative to Adobe’s Lightroom for cataloging and raw developing called DxO PhotoLab, in version 6 as of late 2022. It contains DxO’s Prime and DeepPrime noise reduction routines. However, as with ON1, DxO has spun off just the noise reduction and lens correction parts of PhotoLab into a separate program, PureRAW2, which runs either as a stand-alone app or as a plug-in for Lightroom – but not Photoshop, as PureRAW works only on original raw files.
Unlike all the other programs, PureRAW2 offers essentially no options to adjust settings, just the option to apply, or not, lens corrections, and to choose the output format. For this testing I applied DeepPrime and exported out to DNG files. [See below for a test of DeepPrimeXD, now offered with PureRaw3.]
Version tested: 2.2
Noise Terminator’s controls allow adjusting strength and detail.
Unlike the other programs tested, NoiseXTerminator from astrophotographer Russell Croman is designed specifically for deep-sky astrophotography. It installs as a plug-in for Photoshop or Affinity Photo, but not Lightroom. It is also available under the same purchased licence as a “process” for PixInsight, an advanced program popular with astrophotographers, as it is designed just for editing deep-sky images.
I tested the Photoshop plug-in version of Noise XTerminator. It receives occasional updates to both the actual plug-in and separate updates to the AI module.
Version tested: 1.1.2, AI model 2
NIGHTSCAPE TEST
As with the other test images, the panels show a highly magnified section of the image, indicated in the inset. I shot the image of Lake Louise in Banff, Alberta with a Canon RF15-35mm lens on a 45-megapixel Canon R5 camera at ISO 1600.
The test results on a sample nightscape.
Adobe Camera Raw’s basic noise reduction did a good job, but like all general routines it does soften the image as a by-product of smoothing out high-ISO noise.
ON1 NoNoise 2023 retained landscape detail better than ACR but softened the star trails, despite me adding sharpening. It also produced a somewhat patchy noise smoothing in the sky. This was with Luminosity backed off to 75 from the auto setting (which always cranks up the level to 100 regardless of the image), and with the Tack Sharp routine set to 40 with Micro Contrast at 0. It left a uniform pixel-level mosaic effect in the shadow areas. Despite the new Tack Sharp option, the image was softer than with last year’s NoNoise 2022 version (not shown here as it is no longer available) which produced better shadow results.
Topaz DeNoise AI did a better job than NoNoise retaining the sharp ground detail while smoothing noise, always more obvious in the sky in such images. Even so, it also produced some patchiness, with some areas showing more noise than others. This was with the Standard model set to 40 for Noise and Sharpness, and Recover Details at 75. I show the other model variations below.
Topaz Photo AI did a poor job, producing lots of noisy artifacts in the sky and an over-sharpened foreground riddled with colorful speckling. It added noise. This was with the Normal setting and the default Autopilot settings.
Noiseless AI in Luminar Neo did a decent job smoothing noise while retaining, indeed sharpening ground detail without introducing ringing or colorful edge artifacts. The sky was left with some patchiness and uneven noise smoothing. This was with the suggested Middle setting (vs Low and High) and default levels for Noise, Detail and Sharpness. However, I do like Neo (and Skylum’s earlier Luminar AI) for adding other finishing effects to images such as Orton glows.
DxO PureRAW2 did smooth noise very well while enhancing sharpness quite a lot, almost too much, though it did not introduce obvious edge artifacts. Keep in mind it offers no chance to adjust settings, other than the mode – I used DeepPrime vs the normal Prime. Its main drawback is that in making the conversion back to a raw DNG image it altered the appearance of the image, in this case darkening the image slightly. It also made some faint star trails look wiggly!
Noise XTerminator really smoothed out the sky, and did so very uniformly without doing much harm to the star trails. However, it smoothed out ground detail unacceptably, not surprising given its specialized training on stars, not terrestrial content.
Conclusion: For this image, I’d say Topaz DeNoise AI did the best, though not perfect, job.
This was surprising, as tests I did with earlier versions of DeNoise AI showed it leaving many patchy artifacts and colored edges in places. Frankly, I was put off using it. However, Topaz has improved DeNoise AI a lot.
Why it works so well, when Topaz’s newer program Photo AI works so poorly is hard to understand. Surely they use the same AI code? Apparently not. Photo AI’s noise reduction is not the same as DeNoise AI.
Similarly, ON1’s NoNoise 2023 did a worse job than their older 2022 version. One can assume its performance will improve with updates. The issue seems to be with the new Tack Sharp addition.
NoiseXTerminator might be a good choice for reducing noise in just the sky of nightscape images. It is not suitable for foregrounds, though as of April 2023 its performance on landscapes has improved but is not ideal.
WIDE-FIELD IMAGE TEST
I shot this image of Andromeda and Triangulum with an 85mm Rokinon RF lens on the 45-megapixel Canon R5 on a star tracker. Stars are now points, with small ones easily mistaken for noise. Let’s see how the programs handle such an image, zooming into a tiny section showing the galaxy Messier 33.
The test results on a sample wide-field deep-sky image.
Adobe Camera Raw’s noise and sharpening routines do take care of the worst of the luminance and chrominance noise, but inevitably leave some graininess to the image. This is traditionally dealt with by stacking multiple sub-exposures.
ON1 NoNoise 2023 did a better job than ACR, smoothing the worst of the noise and uniformly, without leaving uneven patchiness. However, it did soften star images, almost like it was applying a 1- or 2-pixel gaussian blur, adding a slight hazy look to the image. And yet the faintest stars that appeared as just perceptible blurs in the original image were sharpened to one- or two-pixel points. This was with only NoNoise AI applied, and no Tack Sharp AI. And, as I show below, NoNoise’s default “High Detail” option introduced with the 2022 version and included in the 2023 edition absolutely destroys star fields. Avoid it.
ON1 NoNoise “High Detail” option ruins star fields, as shown at right. Use “Original” instead.
Topaz DeNoise AI did a better job than Camera Raw, though it wasn’t miles ahead. This was with the Standard setting. Its Low Light and Severe models were not as good, surprising as you might think one of those choices would be the best for such an image. It pays to inspect Topaz’s various models’ results. Standard didn’t erase stars; it actually sharpened the fainter ones, almost a little too much, making them look like specks of noise. Playing with Enhance Sharpness and Recover Detail didn’t make much difference to this behavior.
Topaz Photo AI again performed poorly. Its Normal mode left lots of noise and grainy artifacts. While its Strong mode shown here did smooth background noise better, it softened stars, wiping out the faint ones and leaving colored edges on the brighter ones.
Noiseless AI in Luminar Neo did smooth fine noise somewhat, better than Camera Raw, but still left a grainy background, though with the stars mostly untouched in size and color.
DxO PureRAW2did eliminate noise quite well, while leaving even the faintest stars intact, unlike with the deep-sky image below, which is odd. However, it added some dark halos to bright stars from over-sharpening. And, as with the nightscape example, PureRAW’s output DNG was darker than the raw that went in. I don’t want noise reduction programs altering the basic appearance of an image, even if that can be corrected later in the workflow.
Noise XTerminator performed superbly, as expected – after all, this is the subject matter it is trained to work on. It smoothed out random noise better than any of the other programs, while leaving even the faintest stars untouched, in fact sharpening them slightly. Details in the little galaxy were also unharmed.
Conclusion: The clear winner was NoiseXTerminator.
Topaz DeNoise was a respectable second place, performing better than it had done on such images in earlier versions. Even so, it did alter the appearance of faint stars which might not be desirable.
ON1 NoNoise 2023 also performed quite well, with its softening of brighter stars yet sharpening of fainter ones perhaps acceptable, even desirable for an effect.
TELESCOPIC DEEP-SKY TEST
I shot this image of the NGC 7822 complex of nebulosity with a SharpStar 61mm refractor, using the red-sensitive 30-megapixel Canon Ra and with a narrowband filter to isolate the red and green light of the nebulas.
Again, the test image is a single raw image developed only to re-balance the color and boost the contrast. No dark frames were applied, so the 8-minute exposure at ISO 3200 taken on a warm night shows thermal noise as single “hot pixel” white specks.
The test results on a sample deep-sky close-up.
Adobe Camera Raw did a good job smoothing the worst of the noise, suppressing the hot pixels but only by virtue of it softening all of the image slightly at the pixel level. However, it leaves most stars intact.
ON1 NoNoise 2023 also did a good job smoothing noise while also seeming to boost contrast and structure slightly. But as in the wide-field image, it did smooth out star images a little, though somewhat photogenically, while still emphasizing the faintest stars. This was with no sharpening applied and Luminosity at 60, down from the default 100 NoNoise applies without fail. One wonders if it really is analyzing images to produce optimum settings. With no Tack Sharp sharpening applied, the results on this image with NoNoise 2023 looked identical to NoNoise 2022.
Topaz DeNoise AI did another good job smoothing noise, while leaving most stars unaffected. However, the faintest stars and hot pixels were sharpened to be more visible tiny specks, perhaps too much, even with Sharpening at its lowest level of 1 in Standard mode. Low Light and Severe modes produced worse results, with lots of mottling and unevenness in the background. Unlike NoNoise, at least its Auto settings do vary from image to image, giving you some assurance it really is responding to the image content.
Topaz Photo AI again produced unusable results. Its Normal modes produced lots of mottled texture and haloed stars. Its Strong mode shown here did smooth noise better, but still left lots of uneven artifacts, like DeNoise AI did in its early days. It certainly seems like Photo AI is using old hand-me-down code from DeNoise AI.
Noiseless AI in Luminar Neo did smooth noise but unevenly, leaving lots of textured patches. Stars had grainy halos and the program increased contrast and saturation, adjustments usually best left for specific adjustment layers dedicated to the task.
DxO PureRAW2 did smooth noise very well, including wiping out the faintest specks from hot pixels, but it also wiped out the faintest stars, I think unacceptably and more than other programs like DeNoise AI. For this image it did leave basic brightness alone, likely because it could not apply lens corrections to an image taken with unknown optics. However, it added an odd pixel-level mosaic-like effect on the sky background, again unacceptable.
Noise XTerminator did a great job smoothing random noise without affecting any stars or the nebulosity. The Detail level of 20 I used actually emphasized the faintest stars, but also the hot pixel specks. NoiseXTerminator can’t be counted on to eliminate thermal noise; that demands the application of dark frames and/or using dithering routines to shift each sub-frame image by a few pixels when autoguiding the telescope mount. Even so, Noise XTerminator is so good users might not need to take and stack as many images.
Conclusion: Again, the winner was NoiseXTerminator.
Deep-sky photographers have praised “NoiseX” for its effectiveness, either when applied early on in a PixInsight workflow or, as I do in Photoshop, as a smart filter to the base stacked image underlying other adjustment layers.
Topaz DeNoise is also a good choice as it can work well on many other types of images. But again, play with its various models and settings. Pixel peep!
ON1 NoNoise 2023 did put in a respectable performance here, and it will no doubt improve – it had been out less than a month when I ran these tests.
Based on its odd behavior and results in all three test images I would not recommend DxO’s PureRAW2. Yes, it reduces noise quite well, but it can alter tone and color in the process, and add strange pixel-level mosaic artifacts.
COMPARING DxO and TOPAZ OPTIONS
DxO and Topaz DeNoise AI offer the most choices of AI models and strength of noise reduction. Here I compare:
Topaz DeNoise AI on the nightscape image using three of its models: Standard (which I used in the comparisons above), plus Low Light and Severe. These show how the other models didn’t do as good a job.
The set below also compares DeNoise AI to Topaz’s other program, Photo AI, to show how poor a job it is doing in its early form. Its Strong mode does smooth noise but over-sharpens and leaves edge artifacts. Yes, Photo AI is one-click easy to use, but produces bad results – at least on astrophotos.
Comparing DeNoise’s and Photo AI’s different model settings.
As of this writing DxO’s PureRAW2 offers the Prime and newer DeepPrime AI models – I used DeepPrime for my tests.
However, DxO’s more expensive and complete image processing program, PhotoLab 6, also offers the even newer DeepPrimeXD model, which promises to preserve or recover even more “Xtra Detail” over the DeepPrime model. As of this writing, the XD mode is not offered in PureRAW2. Perhaps that will wait for PureRAW3, no doubt a paid upgrade.
[UPDATE MARCH 2023: DxO has indeed brought out PureRaw3 as a paid upgrade that, as expected, offers the DeepPrimeXD. In testing the new version I found that, while it did not seem to alter an image’s exposure as PureRaw2 did, DeepPrime and DeepPrimeXD still unacceptably ruin starry skies, by either adding a fine-scale mosaic effect (DeepPrime) or weird wormy artifacts (DeepPrimeXD). Try it for yourself to see if you find the same.]
Comparing DxO’s various Prime model settings. DeepPrimeXD is only in PhotoLab 6.
The set above compares the three noise reduction models of DxO’s PhotoLab 6. DeepPrime does do a better job than Prime. DeepPrimeXD does indeed sharpen detail more, but in this example it is too sharp, showing artifacts, especially in the sky where it is adding structures and textures that are not real.
However, when used from within PhotoLab 6, the DeepPrime noise reduction becomes more usable. PhotoLab is then being used to perform all the raw image processing, so PureRAW’s alteration of color and tone is not a concern. Conversely, it can also output raw DNGs with only noise reduction and lens corrections applied, essentially performing the same tasks as PureRAW. If you have PhotoLab, you don’t need PureRAW.
APRIL 2023 UPDATE — TESTING ADOBE’S NEW AI Denoise
In April 2023 Adobe updated Lightroom Classic to v12.3 and the Camera Raw plug-in for Bridge and Photoshop to 15.3. The major new feature was a long-awaited AI noise reduction from Adobe called Denoise. It works only on raw files and generates a new raw DNG file to which all the raw develop settings, including AI masks, can be applied. But the DNG file is some four times larger than the original raw file from the camera.
Here’s a comparison of Camera Raw using the old noise reduction and the new AI option, with DxO’s DeepPrimeXD and Topaz’s PhotoAI, on an aurora image from April 23, 2023:
I used Topaz Photo AI as that’s the program Topaz is now putting all their development effort into, neglecting their other plug-ins such as DeNoise AI. I used DxO PhotoLab 6 with its DeepPrimeXD option to export a DNG with only noise reduction applied, for results identical to what is now offered with DxO’s separate PureRaw3 plug-in.
At 100% above, there’s very little obvious difference. They show up when pixel peeping.
400% blow-ups of the sky – Tap or click to download a full-res JPG
Above are 400% blow-ups of a section of the sky.
Compared to using Adobe’s old noise reduction sliders, their new AI Denoise did a far superior job at smoothing noise, and providing sharpening – almost too much, making even the smallest stars pop out more, perhaps a good thing. But there’s no control of that sharpening.
DxO’s DeepPrimeXD provides a similar, or perhaps more excessive level of AI sharpening. While it smooths noise, it introduces all manner of wormy AI artifacts. It is unacceptable.
Topaz PhotoAI’s noise reduction and sharpening, here both applied with their AutoPilot settings, smoothed noise, but created a patchy appearance. It also softened the stars, despite having sharpening turned on. It was the worst of the set.
400% blow-ups of a section of the ground y – Tap or click to download a full-res JPG
In a similar set of blow-ups of the ground, the old Adobe noise reduction did just that — it smoothed only some noise. The new AI Denoise not only smooths noise, it also applies AI-based sharpening, to the point of almost inventing detail. Here it looks believable, but in other tests I have seen it add content, such as structures in the aurora, that looked fake and out of place. Or just plain wrong!
DxO’s DeepPrimeXD’s main feature over the older DeepPrime is the “eXtra Detail” it finds. Here it produces a result similar to Adobe Denoise, though in some areas of this and other images, I find it is over-sharpening. As with Adobe, there is no option for backing off the sharpening. Other than using DeepPrime or Prime noise reduction.
Topaz PhotoAI didn’t do much to add sharpening. If anything, it made the image softer. While PhotoAI has improved with its weekly updates, it still falls far short of the competition, at least for astrophotos and nightscapes.
The bottom line — Adobe’s new AI Denoise can do a superb job on astrophotos, and will be particularly useful for high-ISO nightscapes, perhaps better than any of the competition. But watch what it does! It can invent details or create results that look artificial. Being able to adjust the sharpening would be helpful. Perhaps that will come in an update.
COMPARING AI TO OLDER NON-AI PROGRAMS
The new generation of AI-based programs have garnered all the attention, leaving older stalwart noise reduction programs looking a little forlorn and forgotten.
Here I compare Camera Raw and two of the best of the AI programs, Topaz DeNoise AI and NoiseXTerminator, with two of the most respected of the “old-school” non-AI programs:
Nik Dfine2’s control interface.
Dfine2, included with the Nik Collection of plug-ins sold by DxO (shown above), and
Reduce Noise v9 sold by Neat Image (shown below).
Neat Image’s Reduce Noise control interface – the simple panel.
I tested both by using them in their automatic modes, where they analyze a section or sections of the image and adjust the noise reduction accordingly, but then apply that setting uniformly across the entire image. However, both allow manual adjustments, with Neat Image’s Reduce Noise offering a bewildering array of technical adjustments.
How do these older programs stack up to the new AI generation? Here are comparisons using the same three test images.
Comparing results with Neat Image and Nik Dfine2 on the nightscape test image.
In the nightscape image, Nik Dfine2 and Neat Image’s Reduce Noise did well, producing uniform noise reduction with no patchiness. But the results weren’t significantly better than with Adobe Camera Raw’s built-in routine. Like ACR, both non-AI programs did smooth detail in the ground, compared to DeNoise AI which sharpened the mountain details.
Comparing results with Neat Image and Nik Dfine2 on the wide-field test image.
In the tracked wide-field image, the differences were harder to distinguish. None performed up to the standard of Noise XTerminator, with both Nik Dfine2 and Neat Image softening stars a little compared to DeNoise AI.
Comparing results with Neat Image and Nik Dfine2 on the deep-sky test image.
In the telescopic deep-sky image, all programs did well, though none matched NoiseXTerminator. None eliminated the hot pixels. But Nik Dfine2 and Neat Image did leave wanted details alone, and did not alter or eliminate desired content. However, they also did not eliminate noise as well as did Topaz DeNoise AI or NoiseXTerminator.
The AI technology does work!
YOUR RESULTS MAY VARY
I should add that the nature of AI means that the results will certainly vary from image to image.
In addition, with many of these programs offering multiple models and settings for strength and sharpening, results even from the same program can be quite different. In this testing I used either the program’s auto defaults or backed off those defaults where I thought the effect was too strong and detrimental to the image.
Software is also a constantly moving target. Updates will alter how these programs perform, we hope for the better. For example, two days after I published this test, ON1 updated NoNoise AI to v17.0.2 with minor fixes and improvements.
And do remember I’m testing on astrophotos, and pixel peeping to the extreme. Rave reviews claiming how well even the poor performers here work on “normal” images might well be valid.
This is all by way of saying, your mileage may vary!
So don’t take my word for it. Most programs (Luminar Neo is an exception) are available as free trial copies to test out on your astro-images and in your preferred workflow. Test for yourself. But do pixel peep. That’s where you’ll see the flaws.
WHAT ABOUT ADOBE?
As noted above, with v15.3 of Camera Raw and v12.3 of Lightroom Classic, Adobe finally introduced their contender into the AI noise reduction contest. And it is a very good entry at that.
But it works only on raw files early in the workflow, and it generates a new raw DNG file, one four times the size of the original. The suggestion is that this technology will expand so that the AI noise reduction can be applied later in the workflow to other file formats.
Indeed, in the last couple of years Adobe has introduced several amazing and powerful “Neural Filters” into Photoshop, which work wonders with one click.
Neural network Noise Reduction is coming to Photoshop. One day!
A neural filter for Noise Reduction is on Adobe’s Wait List for development, so perhaps we will see something in the next few months from Adobe, as a version of the AI noise reduction now offered in Lightroom and Camera Raw.
Until then we have lots of choices for third party programs that all improve with every update. I hope this review has helped you make a choice.
— Alan, November 15, 2022 / Revised April 27, 2023 / AmazingSky.com
In a detailed review, I test a “holy trinity” of premium Canon RF zoom lenses, with astrophotography the primary purpose.
In years past, zoom lenses were judged inferior to fixed-focal length “prime” lenses for the demands of astrophotography. Stars are the severest test of a lens, revealing optical aberrations that would go unnoticed in normal images, or even in photos of test charts. Many older zooms just didn’t cut it for discerning astrophotographers, myself included.
The new generation of premium zooms for mirrorless cameras, from Canon, Nikon and Sony, are dispelling the old wisdom that primes are better than zooms. The new zooms’ optical performance is proving to be as good, if not better than the older generation of prime lenses for DSLR cameras, models often designed decades ago.
The shorter lens-to-sensor “flange distance” offered by mirrorless cameras, along with new types of glass, provide lens designers more freedom to correct aberrations, particularly in wide-angle lenses.
While usually slower than top-of-the-line primes, the advantage of zoom lenses is their versatility for framing and composing subjects, great for nightscapes and constellation shots. It’s nice to have the flexibility of a zoom without sacrificing the optical quality and speed so important for astrophotography. Can we have it all? The new zooms come close to delivering.
The “holy trinity” of Canon zooms tested were purchased in 2021 and 2022. From L to R they are: RF15-35mm, RF28-70mm, and RF70-200mm
A good thing, because with Canon we have little choice! For top-quality glass in wide-angle focal lengths at least, zooms are the only choice for their mirrorless R cameras. As of this writing in late 2022, Canon has yet to release any premium primes for their RF mount shorter than 50mm. Rumours are a 12mm, 24mm, 28mm, and 35mm are coming! But when?
The three zooms I tested are all “L” lenses, designating them as premium-performance models. I have not tested any of Canon’s “economy” line of RF lenses, such as their 24mm and 35mm Macro STM primes. Tests I’ve seen suggest they don’t offer the sharpness I desire for most astrophotography.
Contributing to the lack of choice, top-quality third-party lenses from the likes of Sigma (such as their new 20mm and 24mm Art lenses made for mirrorless cameras) have yet to appear in Canon RF mount versions. Will they ever? In moves that evoked much disdain, Samyang and Viltrox were both ordered by Canon to cease production of their RF auto-focus lenses.
For their mirrorless R cameras, Canon has not authorized any third-party lens makers, forcing you to buy costly Canon L glass, or settle for their lower-grade STM lenses, or opt for reverse-engineered manual-focus lenses from makers such as TTArtisan and Laowa/Venus Optics. While they are good, they are not up to the optical standards of Canon’s L-series glass.
I know, as I own several RF-mount TTArtisan wide-angle lenses and the Laowa 15mm f/2 lens. You can find my tests of those lenses at AstroGearToday.com. Look under Reviews: Astrophotography Gear.
RF lenses will fit only on Canon R-series mirrorless cameras. This shows the RF15-35mm on the Canon R5 used for the lens testing.
The trio of RF lenses tested here work on all Canon EOS R-series cameras, including their R7 and R10 cropped-frame cameras. However, they will not work on any Canon DSLRs.
Two of the lenses, the RF15-35mm F/2.8 and RF70-200mm F/4, are designs updated from older Canon DSLR lenses with similar specs. The RF28-70mm F/2 does not have an equivalent focal length range and speed in Canon’s DSLR lens line-up. Indeed, nobody else makes a lens this fast covering the “normal” zoom range.
Together, the three lenses cover focal lengths from 15mm to 200mm, with some overlap. A trio of zooms like this — a wide-angle, normal, and telephoto — is often called a “holy trinity” set, a popular combination all camera manufacturers offer to cover the majority of applications.
However, my interest was strictly for astrophotography, with stars the test subjects.
NOTE: CLICK or TAP on a test image to download a full-resolution image for closer inspection. The images, while low-compression JPGs, are large and numerous, and so will take time to fully load and display. Patience!
I tested the trio of lenses on same-night exposures of a starry but moonlit sky, using the 45-megapixel Canon R5 camera mounted on a motorized star tracker to follow the rotating sky. With one exception noted, any distortion of stars from perfect pinpoints is due to lens aberrations, not star trailing. The brighter moonlit sky helped reveal non-uniform illumination from lens vignetting.
I shot each lens wide-open at its maximum aperture, as well as one stop down from maximum, to see how aberrations and vignetting improved.
I did not test auto-focus performance, nor image stabilization (only the RF28-70mm lacks internal IS), nor other lens traits unimportant for astro work such as bokeh or close focus image quality.
I also compared the RF15-35mm on same-night dark-sky tests against a trio of prime lenses long in my stable: the Rokinon 14mm SP, and Canon’s older L-series 24mm and 35mm primes, all made for DSLRs.
The lenses each come with lens hoods that use a click-on mechanism much easier to twist on and off than with the older design used on Canon EF lenses.
TL;DR SUMMARY
Each of the Canon “holy trinity” of zoom performs superbly, though not without some residual lens aberrations such as corner astigmatism and, in the RF28-70mm, slight chromatic aberration at f/2.
However, what flaws they show are well below the level of many older prime lenses made for DSLR cameras.
The RF lenses’ major optical flaw is vignetting, which can be quite severe at some focal lengths, such as in the RF70-200mm at 200mm. But this flaw can be corrected in processing.
These are lenses that can replace fixed-focal length primes, though at considerable cost, in part justifiable in that they negate the need for a suite of many prime lenses.
The performance of these and other new lenses made for mirrorless cameras from all brands is one good reason to switch from DSLR to mirrorless cameras.
Lens Specs and Applications
Canon RF15-35mm F/2.8 L IS USM
The RF15-35mm is a fine nightscape lens. It extends slightly when zooming with the lens physically longest at its shortest 15mm focal length.
The Canon RF15-35mm F/2.8 L is made primarily for urban photography and landscapes by day. My main application is using it to take landscapes by night, and auroras, where its relatively fast f/2.8 speed helps keeps exposure times short and ISO speeds reasonably low. However, the RF15-35mm can certainly be used for tracked wide-angle Milky Way and constellation portraits.
The lens weighs a moderate 885 grams (31 ounces or 1.9 pounds) with lens hood and end caps, and accepts 82mm filters, larger than the 72mm or 77mm filter threads of most astrophoto-friendly lenses. Square 100mm filters will work well on the lens, even at the 15mm focal length. There are choices, such as from KASE, for light pollution reduction and star diffusion filters in this size and format. I have reviews of these filters at AstroGearToday.com, both here for light pollution filters and here for starglow filters.
Canon offers a lower-cost alternative in this range, their RF14-35mm. But it is f/4, a little slow for nightscape, aurora, and Milky Way photography. I have not tested one.
Canon RF28-70mm F/2 L USM
The RF28-70mm works great for tracked starfields and constellations. It extends when zooming, with it longest at its 70mm focal length.
The big Canon RF28-70mm F/2 is aimed at wedding and portrait photographers, though the lens is suitable for landscape work. While I do use it for nightscapes, my primary use is for tracked Milky Way and constellation images, where its range of fields of view nicely frames most constellations, from big to small.
I justified its high cost by deciding it replaces (more or less!) prime lenses in the common 24mm, 35mm, 50mm, and 85mm focal lengths. Its f/2 speed does bring it into fast prime lens territory. It’s handy to have just one lens to cover the range.
Canon offers a lower-cost alternative here, too, their RF24-70mm. But it is f/2.8. While this is certainly excellent speed, I like having the option of shooting at f/2. An example is when using narrowband nebula filters such as red hydrogen-alpha filters, where shooting at f/2 keeps exposures shorter and/or ISOs lower when using such dense filters. I use this lens with an Astronomik 12-nanometre H-α clip-in filter. An example is in one of the galleries below.
While a clip-in filter shifts the infinity focus point inward (to as close as the 2-metre mark with the RF28-70mm at 28mm, and to 6 metres at 70mm), I did not find that shift adversely affected the lens’s optical performance. That’s not true of all lenses.
Make no mistake, the RF28-70mm is one hefty lens, weighing 1530 grams (54 ounces or 3.4 pounds). Its front-heavy mass demands a solid tripod head. Its large front lens accepts big 95mm filters, a rare size with few options available. I found one broadband light pollution filter in this size, from URTH. Otherwise, you need to use in-body clip-in filters. Astronomik makes a selection for Canon EOS R cameras.
Canon RF70-200mm F/4 L IS USM
The RF70-200mm works well for closeups of landscape scenes such as moonrises. It extends the most of all the lenses when zooming to its longest focal length.
The Canon RF70-200mm F/4 is another portrait or landscape lens. I use it primarily for bright twilight planet conjunctions and moonrise scenes, where its slower f/4 speed is not a detriment. However, as my tests show, it can be used for tracked deep-sky images, where it is still faster than most short focal length telescopes.
The RF70-200mm lens weighs 810 grams (28 ounces, or 1.75 pounds) with lens hood and caps, so is light for a 70-to-200mm zoom. It is also compact. At just 140mm long when set to 70mm, it is actually the shortest lens of the trio. However, the barrel extends to 195mm long when zoomed out to 200mm focal length.
Canon offers the more costly and, at 1200 grams, heavier RF70-200mm F/2.8 lens which might be a better choice for deep-sky imaging where the extra stop of speed can be useful. But in this case, I chose the slower, more affordable – though still not cheap – f/4 version. It accepts common 77mm filters, as does the f/2.8 version.
Centre Sharpness
Canon RF15-35mm F/2.8 L IS USM
This compares 400% blow-ups of the frame centres at the two extreme focal lengths and at two apertures: wide open at f/2.8 and stopped down to f/4.
Like the other two zoom lenses tested, the RF15-35mm is very sharp on axis. Even wide open, there’s no evidence of softness and star bloat from spherical aberration, the bane of cheaper lenses.
Coloured haloes from longitudinal chromatic aberration are absent, except at 28mm and 35mm (shown here) when wide open at f/2.8, where bright stars show a little bit of blue haloing. At f/4, this minor level of aberration disappears.
Canon RF28-70mm F/2 L USM
This compares 400% blow-ups of the frame centres at the two extreme focal lengths and at two apertures: wide open at f/2 and stopped down to f/2.8.
The big RF28-70mm is also very sharp on-axis but is prone to more chromatic aberration at f/2, showing slight magenta haloes on bright stars at the shorter focal lengths and pale cyan haloes at 70mm in my test shots. Such false colour haloes can be very sensitive to precise focus, though with refractive optics the point of least colour is often not the point of sharpest focus.
At f/2, stars are a little softer at 70mm than at 28mm. Stopping down to f/2.8 eliminates this slight softness and most of the longitudinal chromatic aberration.
Canon RF70-200mm F/4 L IS USM
This compares 400% blow-ups of the frame centres at the two extreme focal lengths and at two apertures: wide open at f/4 and stopped down to f/5.6.
Unlike prime telephotos I’ve used, the RF70-200mm shows negligible chromatic aberration on-axis at all focal lengths, even at f/4. Stars are a little softer at the longest focal length at f/4, perhaps from slight spherical aberration, though my 200mm test shots are also affected by a little mistracking, trailing the stars slightly.
Stopping down to f/5.6 sharpens stars just that much more at 200mm.
Corner Aberrations
The corners are where we typically separate great lenses from the merely good. And it is where zoom lenses have traditionally performed badly. For example, my original Canon EF16-35mm f/2.8 lens was so bad off-axis I found it mostly unusable for astro work. Not so the new RF15-35mm, which is the RF replacement for Canon’s older EF16-35mm.
To be clear – in these test shots you might think the level of aberrations are surprising for premium lenses. But keep in mind, to show them at all I am having to pixel-peep by enlarging all the test images by 400 percent, cropping down to just the extreme corners.
Check the examples in the Compared to DSLR Lenses section and in the Finished ImagesGalleries for another look at lens performance in broader context.
Canon RF15-35mm F/2.8 L IS USM
This compares 400% blow-ups of the extreme corners at five focal lengths with the RF15-35mm wide open at f/2.8
Surprisingly, this RF’s best performance off-axis is actually at its shortest focal length. At 15mm it exhibits only some slight tangential astigmatism, elongating stars away from the frame centre. At 24mm aberrations appear slightly worse than at the other focal lengths, showing some flaring from sagittal astigmatism and perhaps coma as well, aberrations seen to a lesser degree at 28mm and 35mm, making stars look like little three-pointed triangles.
This compares 400% blow-ups of the extreme corners at five focal lengths with the RF15-35mm stopped down one stop to f/4.
The aberrations reduce when stopped down to f/4, but are still present, especially at 24mm, this lens’s weakest focal length, though only just.
While the RF15-35mm isn’t perfect, it outperforms other prime lenses I have, and that I suspect most users will own or have used in the past with DSLRs. Only new wide-angle premium primes for the RF mount, if and when we see them, will provide better performance.
Canon RF28-70mm F/2 L USM
This compare 400% blow-ups of the extreme corners at four focal lengths with the RF28-70mm wide open at f/2.
The RF28-70mm’s fast f/2 speed, unusual for any zoom lens, was surely a challenge to design for. Off-axis when wide open at f/2 it does show astigmatism at the extreme corners at all focal lengths, but the least at 50mm, and the worst at 28mm where a little lateral chromatic aberration is also visible, adding slight colour fringing.
This compare 400% blow-ups of the extreme corners at four focal lengths with the RF28-70mm stopped down one stop to f/2.8.
Sharpness off-axis improves markedly when stopped down one stop to f/2.8, where at 50mm stars are now nearly perfect to the corners. Indeed, performance is so good at 50mm, I think there would be little need to buy the Canon RF50mm prime, unless its f/1.2 speed is deemed essential.
With the RF28-70mm at f/2.8, stars still show some residual astigmatism at 28mm and 35mm, but only at the extreme corners.
Canon RF70-200mm F/4 L IS USM
This compare 400% blow-ups of the extreme corners at four focal lengths with the RF70-200mm wide open at f/4.
The RF70-200mm telephoto zoom shows some astigmatism and coma at the corners when wide open at f/4, with it worse at the shorter focal lengths. While lens corrections have been applied here, the 200mm image still shows a darker corner from the vignetting described below.
This compare 400% blow-ups of the extreme corners at four focal lengths with the RF70-200mm stopped down one stop to f/5.6.
Stopping down to f/5.6 eliminates most of the off-axis aberrations at 135mm and 200mm focal lengths but some remain at 70mm and to a lesser degree at 100mm.
This is a lens that can be used at f/4 even for the demands of deep-sky imaging, though perfectionists will want to stop it down. At f/5.6 it is similar in speed to many astrographic refractors, though most of those start at about 250mm focal length.
Frame Vignetting
In the previous test images, I applied lens corrections (but no other adjustments) to each of the raw files in Adobe Camera Raw, using the settings ACR automatically selects from its lens database. These corrections brightened the corners.
In this next set I show the lenses’ weakest point, their high level of vignetting. This light falloff darkens the corners by a surprising amount. In the new generation of lenses for mirrorless cameras, it seems lens designers are choosing to sacrifice uniform frame illumination in order to maximize aberration corrections. The latter can’t be corrected entirely, if at all, by software.
However, corrections applied either in-camera or at the computer can brighten corners, “flattening” the field. I show that improvement in the section that follows this one.
Canon RF15-35mm F/2.8 L IS USM
This compares the level of vignetting present in the RF15-35mm without the benefit of lens corrections, showing the difference at five focal lengths.
In the wide-angle zoom, vignetting darkens just the corners at 15mm, but widens to affect progressively more of the frame at the longer focal lengths. The examples show the entire right side of the frame. I show the effect just at f/2.8.
Though I don’t show examples with the two wider zooms, with all lenses vignetting decreases dramatically when each lens is stopped down by even one stop. The fields become much more evenly illuminated, though some darkening at the very corners remains one stop down.
Canon RF28-70mm F/2 L USM
This compares the level of vignetting present in the RF28-70mm without the benefit of lens corrections, showing the difference at four focal lengths.
In this “normal” zoom, vignetting performance is similar at all focal lengths, though it affects a bit more of the field at 70mm than at 28mm. Again, while I’m not presenting an example, vignetting decreases a lot when this lens is stopped down to f/2.8. While the extra stop of speed is certainly nice to have at times, I usually shoot the RF28-70mm at f/2.8.
Canon RF70-200mm F/4 L IS USM
This compares the level of vignetting present in the RF70-200mm without the benefit of lens corrections, showing the difference at four focal lengths.
In this telephoto zoom, vignetting is fairly mild at the shorter focal lengths but becomes severe at 200mm, affecting much of the field. It is far worse than I see with my older Canon EF200mm f/2.8 prime, a lens that is not as sharp at f/4 as the RF zoom.
The faster RF70-200mm f/2.8 lens, which I had the chance to test one night last year, showed as much, if not more, vignetting than the f/4 version. See my test here at AstroGearToday.com. I thought the f/4 version would be better for vignetting, but it is not.
This shows how much the RF-70-200mm’s vignetting improves when it is stopped down.
In this case, as the vignetting is so prominent at 200mm, I show above how much it improves when stopped down to f/5.6, in a comparison with the lens at f/4, both with no lens corrections applied in processing. The major improvement comes from the smaller aperture alone. For twilight scenes, I’d suggest stopping this lens down to better ensure a uniform sky background.
LENS Corrections
In this next set I show how well applying lens corrections improves the vignetting at the focal lengths where each of the lenses is at its worse, and with each at its widest aperture.
I show this with Adobe Camera Raw but Lightroom would provide identical results. I did not test lens corrections with other programs such as CaptureOne, DxO PhotoLab, or ON1 Photo Raw, which all have automatic lens corrections as well.
Canon RF15-35mm F/2.8 L IS USM
This compare the RF15-35mm lens at f/2.8 and 35mm with and without lens corrections applied, to show how much they improve the vignetting.
Applying lens corrections in Adobe Camera Raw certainly brightened the corners and edges, though still left some darkening at the very corners that can be corrected by hand in the Manual tab.
Canon RF28-70mm F/2 L USM
This compare the RF28-70mm lens at f/2 and 70mm with and without lens corrections applied, to show how much they improve the vignetting.
ACR’s lens corrections helped but did not completely eliminate the vignetting here. Corner darkening remained. Manually increasing the vignetting slider can provide that extra level of correction needed.
Canon RF70-200mm F/4 L IS USM
This compare the RF70-200mm lens at f/4 and 200mm with and without lens corrections applied, to show how much they improve the vignetting.
The high level of vignetting with this lens at 200mm largely disappeared with lens corrections, though not entirely. For deep-sky imaging, users might prefer to shoot and apply flat-field frames. I prefer to apply automatic and manual corrections to the raw files, to stay within a raw workflow as much as possible.
Same Focal Length Comparisons
With the trio of lenses offering some of the same focal lengths, here I show how they compare at three of those shared focal lengths. I zoom into the upper right corners here, as with the Corner Aberrations comparisons above.
RF15-35mm vs. RF28-70mm at 28mm
This compares the RF15-35mm at 28mm to the RF28-70mm also at 28mm and with both at f/2.8.
With both lenses at 28mm and at the same f/2.8 aperture (though the RF28-70mm is now stopped down one stop), it’s a toss up. Both show corner aberrations, though of a different mix, distorting stars a little differently. The RF28-70mm shows some lateral chromatic aberration, but the RF15-35mm shows a bit more flaring from astigmatism.
RF15-35mm vs. RF28-70mm at 35mm
This compares the RF15-35mm at 35mm to the RF28-70mm also at 35mm and with both at f/2.8.
The story is similar with each lens at 35mm. Stars seem a bit sharper in the RF15-35mm though are elongated more by astigmatism at the very corners. Lens corrections have been applied here and with the other two-lens comparison pairs.
RF28-70mm vs. RF70-200mm at 70mm
This compares the RF28-70mm at 70mm and f/2.8 to the RF70-200mm also at 70mm but wide open at f/4.
Here I show the RF28-70mm at f/2.8 and the RF70-200mm wide open at f/4, with both set to 70mm focal length. The telephoto lens shows a little more softening and star bloating from corner aberrations, though both perform well.
Compared to DSLR Lenses
Here I try to demonstrate just how much better at least one of the zooms on test here is compared to older prime lenses made for DSLRs. The Canon lenses are labeled EF, for Canon’s EF lens mount used for decades on their DSLRs and EOS film cameras. Both are premium L lenses.
I shot this set on a different night than the previous examples, with some light cloud present which added various amounts of glows around stars. But the test shots still show corner sharpness and aberrations well, in this case of the upper left corners of all frames.
Canon RF15-35mm at 35mm vs. Canon EF35mm L
This compares the RF15-35mm zoom at 35mm to the older EF35mm L prime lens. Some light cloud added the glows at right.
The Canon EF35mm is the original Mark I version, which Canon replaced a few years ago with an improved Mark II model. So I’m sure if you were to buy an EF35mm lens now (or if that’s the model you own) it will perform better than what I show here.
Both lenses are at f/2.8, wide open for the RF lens, but stopped down two stops for the f/1.4 EF lens.
The zoom lens is much sharper to the corners, with far less astigmatism and none of the lateral chromatic aberration and field curvature (softening stars at the very corner) of the old EF35mm prime. I thought the EF35mm was a superb lens, and used it a lot over the last 15 years for Milky Way panoramas. I would not use it now!
Canon RF15-35mm at 24mm vs. Canon EF24mm L
This compares the RF15-35mm zoom at 24mm to the older EF24mm L prime lens.Some light cloud added the glows at right.
Bought in the early years of DSLRs, the EF24mm tested here is also an original Mark I model, since replaced by an improved Mark II 24mm. The old 24mm is good, but shows more astigmatism than the RF lens, and some field curvature and purple chromatic aberration not present at all in the RF lens.
And this is comparing it to the RF lens at its weakest focal length, 24mm. It still handily outperforms the old EF24mm prime.
Canon RF15-35mm at 15mm vs. Rokinon 14mm SP
This compares the RF15-35mm at 15mm to the Rokinon 14mm SP prime lens.
Canon once made an EF14mm f/2.8 L prime, but I’ve never used it. For a lens in this focal length, one popular with nightscape photographers, I’ve used the ubiquitous Rokinon/Samyang 14mm f/2.8 manual lens. While a bargain at about $300, I always found it soft and aberrated at the corners. See my test of 14mm ultra-wides here.
A few years ago I upgraded to the Rokinon 14mm f/2.4 lens in their premium SP series (about $800 for the EF-mount version). While a manual lens, it does have electrical contacts to communicate lens metadata to the camera. Like all EF-mount lenses from any brand, it can be adapted to Canon R cameras using Canon’s $100 EF-EOS R lens adapter.
Older DSLR lenses like the Rokinon SP can be adapted to all Canon R cameras with the Canon lens adapter ring which transmits lens data to the camera.
The Rokinon SP is the only prime I found that beat the RF zoom. It provided sharper images to the corners than the RF15-35mm at 15mm. The Rokinon also offers the slightly faster maximum aperture of f/2.4 (which Canon cameras register as f/2.5). Vignetting is severe, but like the RF lenses can be corrected – Camera Raw has this lens in its database. What is not so easy to correct is some slight colour shift at the corners.
Another disadvantage, as with many other 14mm lenses, is that the SP lens cannot accept front-mounted filters. The RF15-35mm can.
Nevertheless, until Canon comes out with a 12mm to 14mm RF prime, or allows Sigma to, an adapted Rokinon 14mm SP is a good affordable alternative to the RF15-35mm.
The RF15-35mm (left) takes 82mm filters, the RF28-70mm (centre) requires 95mm filters, but the RF70-200mm (right) can accept common 77mm filters.
Mechanical Points
All the RF lens bodies are built of weight-saving engineered plastic incorporating thorough weather sealing. There is nothing cheap about their fit, finish or handling. Each lens has textured grip rings for the zoom, focus and a control ring that can be programmed to adjust either aperture, ISO, exposure compensation or other settings of your choosing.
As with all modern auto-focus lenses, the manual focus ring on each lens does not mechanically move glass. It controls a motor that in turn focuses the lens, so-called “focus-by-wire.” However, I found that focus could be dialled in accurately. But if the camera is turned off, then on again, the lens will not return to its previous focus position. You have to refocus to infinity each time the camera is powered up, a nuisance.
Unlike some Nikon, Sony, Samyang, and Sigma lenses, none of the Canon lenses have a focus lock button, or any way of presetting an infinity focus point, or simply having the lens remember where it was last set. I would hope Canon could address that deficiency in a firmware update.
With all the zooms, I did not find any issue with “zoom creep.” The telescoping barrels remained in place during long exposures and did not slowly retract when aimed up. While the RF28-70mm and RF70-200mm each have a zoom lock switch, it locks the lens only at its shortest focal length.
Each lens is parfocal within its zoom range. Focus at one zoom position, and it will be in focus for all the focal lengths. I usually focus at the longest focal length where it is easiest to judge focus by eye, then zoom out to frame the scene.
FINISHED IMAGES GALLERIES
Here I present a selection of final, processed images (four for each lens), so you can better see how each performs on real-world celestial subjects. To speed download, the images are downsized to 2048 pixels wide.
As per my comments at top, the RF15-35mm is my primary nightscape lens, the RF28-70mm my lens for wide-field constellation and Milky Way shots, while the RF70-200mm is for conjunctions and Moon scenes. It would also be good for eclipses.
Image Gallery withCanon RF15-35mm F/2.8 L IS USM
Image Gallery withCanon RF28-70mm F/2 L USM
Orion in H-Alpha Light with Narrowband Filter
Image Gallery withCanon RF70-200mm F/4 L IS USM
Click on the images to bring them up full screen with caption information.
CONCLUSIONs and recommendations
If you are a Canon user switching from your aging but faithful DSLR to one of their mirrorless R cameras, each of these lenses will perform superbly for astrophotography. At a price! Each is costly. But the cost of older EF lenses has also increased in recent months.
The other native RF L-series lenses in this focal length range, Canon’s RF50mm and RF85mm f/1.2 primes, are stunning … but also expensive. As I’m sure any coming RF wide-angle L primes will be, if and when they ever appear!
This shows the relative difference in size and height of the lens trio, with all collapsed to their minimum size.
The cheaper alternative – not the least because you might already own them! – is using adapted EF-mount lenses made for DSLRs, either from Canon or other brands. But in many cases, as I’ve shown, the new RF glass is sharper, especially when on a high-resolution camera such as the Canon R5 I used for all the testing.
And there’s the harsh reality that Canon is discontinuing many EF lenses. You can now buy some only used. For example, the EF135mm f/2 L and EF200mm f/2.8 L are both gone.
Until Canon licenses other companies to issue approved lenses for their RF mount – if that happens at all – our choices for native RF lenses are limited. However, the quality of Canon’s L lenses is superb. I now use these zooms almost exclusively, and financed most of their considerable cost by selling off a ream of older cameras and lenses.
If there’s one lens to buy for most astrophotography, it might be the big RF28-70mm F/2, a zoom lens that comes close to offering it all: flexibility, optical quality and speed. The RF24-70mm F/2.8 is a more affordable choice, though I have not tested one.
If nightscapes are the priority, the RF15-35mm F/2.8 would see a lot of use, as perhaps the only lens you’d need.
Of the trio, the RF70-200mm was the lowest priority on my wish list. But it has proven to be very useful for framing horizon scenes.
The superb optics of these and other new lenses made for mirrorless cameras is one good reason to upgrade from a DSLR to a mirrorless camera, in whatever brand you prefer.
In an extensive technical blog, I put the Canon R6 mirrorless camera through its paces for the demands of astrophotography.
Every major camera manufacturer, with the lone exception of stalwart Pentax, has moved from producing digital lens reflex (DSLR) cameras, to digital single lens mirrorless (DSLM) cameras. The reflex mirror is gone, allowing for a more compact camera, better movie capabilities, and enhanced auto-focus functions, among other benefits.
But what about for astrophotography? I reviewed the Sony a7III and Nikon Z6 mirrorless cameras here on my blog and, except for a couple of points, found them excellent for the demands of most astrophotography.
For the last two years I’ve primarily used Canon’s astro-friendly and red-sensitive EOS Ra mirrorless, a model sadly discontinued in September 2021 after just two years on the market. I reviewed that camera in the April 2020 issue of Sky & Telescope magazine, with a quick first look here on my blog.
The superb performance of the Ra has prompted me to stay with the Canon mirrorless R system for future camera purchases. Here I test the mid-priced R6, introduced in August 2020.
NOTE: In early November 2022 Canon announced the EOS R6 MkII, which one assumes will eventually replace the original R6 once stock of that camera runs out. The MkII has a 24 Mp sensor for slightly better resolution, and offers longer battery life. But the main improvements over the R6 is to autofocus accuracy, a function of little use to astrophotographers. Only real-world testing will tell if the R6 MkII has better or worse noise levels than the R6, or has eliminated the R6’s amp glow, reported on below.
M31, the spiral galaxy in Andromeda, with the Canon R6 mirrorless camera. It is a stack of 8 x 8-minute exposures at ISO 800, blended with a stack of 8 x 2-minute exposures at ISO 400 for the core, to prevent it from overexposing too much, all with a SharpStar 76mm apo refractor at f/4.5 with its field flattener/reducer.
TL;DR SUMMARY
The Canon R6 has proven excellent for astrophotography, exhibiting better dynamic range and shadow recovery than most Canon DSLRs, due to the ISO invariant design of the R6 sensor. It is on par with the low-light performance of Nikon and Sony mirrorless cameras.
The preview image is sensitive enough to allow easy framing and focusing at night. The movie mode produces usable quality up to ISO 51,200, making 4K movies of auroras possible. Canon DSLRs cannot do this.
Marring the superb performance are annoying deficiencies in the design, and one flaw in the image quality – an amp glow – that particularly impacts deep-sky imaging.
R6 pros
The Canon R6 is superb for its:
Low noise, though not exceptionally so
ISO invariant sensor performance for good shadow recovery
Sensitive live view display with ultra-high ISO boost in Movie mode
Relatively low noise Movie mode with full frame 4K video
Low light auto focus and accurate manual focus assist
Good battery life
R6 cons
The Canon R6 is not so superb for its:
Design Deficiencies
Lack of a top LCD screen
Bright timer display in Bulb on the rear screen
No battery level indication when shooting
Low grade R3-style remote jack, same as on entry-level Canon DSLRs
Image Quality Flaw
Magenta edge “amp glow” in long exposures
The Canon Ra on the left with the 28-70mm f/2 RF lens and the Canon R6 on the right with the 70-200mm f/2/8 RF lens, two superb but costly zooms for the R system cameras.
CHOOSING THE R6
Canon’s first full-frame mirrorless camera, the 30-megapixel EOS R, was introduced in late 2018 to compete with Sony. As of late-2021 the main choices in a Canon DSLM for astrophotography are either the original R, the 20-megapixel R6, the 26-megapixel Rp, or the 45-megapixel R5.
The new 24-megapixel Canon R3, while it has impressive low-noise performance, is designed primarily for high-speed sports and news photography. It is difficult to justify its $6,000 cost for astro work.
I have not tested Canon’s entry-level, but full-frame Rp. While the Rp’s image quality is likely quite good, its small battery and short lifetime on a single charge will be limiting factors for astrophotography.
Nor have I tested the higher-end R5. Friends who use the R5 for nightscape work love it, but with smaller pixels the R5 will be noisier than the R6, which lab tests at sites such as DPReview.com seem to confirm.
Meanwhile, the original EOS R, while having excellent image quality and features, is surely destined for replacement in the near future – with a Canon EOS R Mark II? The R’s successor might be a great astrophoto camera, but with the Ra gone, I feel the R6 is currently the prime choice from Canon, especially for nightscapes.
I tested an R6 purchased in June 2021 and updated in August with firmware v1.4. I’ll go through its performance and functions with astrophotography in mind. I’ve ignored praised R6 features such as eye tracking autofocus, in-body image stabilization, and high speed burst rates. They are of limited or no value for astrophotography.
Along the way, I also offer a selection of user tips, some of which are applicable to other cameras.
LIVE VIEW FOCUSING AND FRAMING
“Back-of-the-camera” views of the R6 in its normal Live View mode (upper left) and its highly-sensitive Movie Mode (upper right), compared to views with four other cameras. Note the Milky Way visible with the R6 in its Movie mode, similar to the Sony in Bright Monitoring mode.
The first difference you will see when using any new mirrorless camera, compared to even a high-end DSLR, is how much brighter the “Live View” image is when shooting at night. DSLM cameras are always in Live View – even the eye-level viewfinder presents a digital image supplied by the sensor.
As such, whether on the rear screen on in the viewfinder, you see an image that closely matches the photo you are about to take, because it is the image you are about to take.
To a limit. DSLMs can do only so much to simulate what a long 30-second exposure will look like. But the R6, like many DSLMs, goes a long way in providing a preview image bright enough to frame a dark scene and focus on bright stars. Turn on Exposure Simulation to brighten the live image, and open the lens as wide as possible.
The Canon R6 in its Movie Mode at ISO 204,800 and with a lens wide open.
But the R6 has a trick up its sleeve for framing nightscapes. Switch the Mode dial to Movie, and set the ISO up to 204,800 (or at night just dial in Auto ISO), and with the lens wide open and shutter on 1/8 second (as above), the preview image will brighten enough to show the Milky Way and dark foreground, albeit in a noisy image. But it’s just for aiming and framing.
This is similar to the excellent, but well-hidden Bright Monitoring mode on Sony Alphas. This high-ISO Movie mode makes it a pleasure using the R6 for nightscapes. The EOS R and Ra do not have this ability. While their live view screens are good, they are not as sensitive as the R6’s, with the R and Ra’s Movie modes able to go up to only ISO 12,800. The R5 can go up to “only” ISO 51,200 in its Movie mode, good but not quite high enough for live framing on dark nights.
Comparing Manual vs. Auto Focus results with the R6.
The R6 will also autofocus down to a claimed EV -6.5, allowing it to focus in dim light for nightscapes, a feat impossible in most cameras. In practice with the Canon RF 15-35mm lens at f/2.8, I found the R6 can’t autofocus on the actual dark landscape, but it can autofocus on bright stars and planets (provided, of course, the camera is fitted with an autofocus lens).
Autofocusing on bright stars proved very accurate. By comparison, while the Ra can autofocus on distant bright lights, it fails on bright stars or planets.
Turning on Focus Peaking makes stars turn red, yellow or blue (your choice of colours) when they are in focus, as a reassuring confirmation.
The Focus Peaking and Focus Guide menu.The R6 live view display with Focus Guide arrows on and focused on a star, Antares.
In manual focus, an additional Focus Aid overlay provides arrows that close up and turn green when in focus on a bright star or planet. Or you can zoom in by 5x or 10x to focus by eye the old way by examining the star image. I wish the R6 had a 15x or 20x magnification; 5x and 10x have long been the Canon standards. Only the Ra offered 30x for ultra-precise focusing on stars.
In all, the ease of framing and focusing will be the major improvement you’ll enjoy by moving to any mirrorless, especially if your old camera is a cropped-frame Canon Rebel or T3i! But the R6 particularly excels at ease of focusing and framing.
NOISE PERFORMANCE
The key camera characteristic for astrophoto use is noise. I feel it is more important than resolution. There’s little point in having lots of fine detail if it is lost in a blizzard of high-ISO noise. And for astro work, we are almost always shooting at high ISOs.
Comparing the R6’s noise at increasingly higher ISO speeds on a starlit nightscape.
With just 20 megapixels, low by today’s standards, the R6 has individual pixels, or more correctly “photosites,” that are each 6.6 microns in size, the “pixel pitch.”
By comparison, the 30-megapixel R (and Ra) has a pixel pitch of 5.4 microns, the 45-megapixel R5’s pixel pitch is 4.4 microns, while the acclaimed low-light champion in the camera world, the 12-megapixel Sony a7sIII, has large 8.5-micron photosites.
The bigger the photosites (i.e. the larger the pixel pitch), the more photons each photosite can collect in a given amount of time – and the more photons they can collect, period, before they overfill and clip highlights. More photons equals more signal, and therefore a better signal-to-noise ratio, while the greater “full-well depth” yields higher dynamic range.
Each generation of camera also improves the signal-to-noise ratio by suppressing noise via its sensor design and improved signal processing hardware and firmware. The R6 uses Canon’s latest DIGIC X processor shared by the company’s other mirrorless cameras.
Comparing the R6noise with the 6D MkII and EOS Ra on a deep-sky subject, galaxies.
In noise tests comparing the R6 against the Ra and Canon 6D Mark II, all three cameras showed a similar level of noise at ISO settings from 400 up to 12,800. But the 6D Mark II performed well only when properly exposed. Both the R6 and Ra performed much better for shadow recovery in underexposed scenes.
Comparing the R6noise with with the 6D MkII and EOS Ra on a shadowed nightscape.Comparing the R6 noise with the EOS Ra on the Andromeda Galaxy at typical deep-sky ISO speeds.
In nightscapes and deep-sky images the R6 and Ra looked nearly identical at each of their ISO settings. This was surprising considering the Ra’s smaller photosites, which perhaps attests to the low noise of the astronomical “a” model.
Or it could be that the R6 isn’t as low noise as it should be for a 20 megapixel camera. But it is as good as it gets for Canon cameras, and that’s very good indeed.
I saw no “magic ISO” setting where the R6 performed better than at other settings. Noise increased in proportion to the ISO speed. It proved perfectly usable up to ISO 6400, with ISO 12,800 acceptable for stills when necessary.
ISO INVARIANCY
The flaw in many Canon DSLRs, one documented in my 2017 review of the 6D Mark II, was their poor dynamic range due to the lack of an ISO invariant sensor design.
The R6, as with Canon’s other R-series cameras, has largely addressed this weakness. The sensor in the R6 appears to be nicely ISO invariant and performs as well as the Sony and Nikon cameras I have used and tested, models praised for their ISO invariant behaviour.
Where this trait shows itself to advantage is on nightscapes where the starlit foreground is often dark and underexposed. Bringing out detail in the shadows in raw files requires a lot of Shadow Recovery or increasing the Exposure slider. Images from an ISO invariant sensor can withstand the brightening “in post” far better, with minimal noise increase or degradations such as a loss of contrast, added banding, or horrible discolourations.
Comparing the R6 for ISO Invariancy on a starlit nightscape.
To test the R6, I shot sets of images at the same shutter speed, one well-exposed at a high ISO, then several at successively lower ISOs to underexpose by 1 to 5 stops. I then brightened the underexposed images by increasing the Exposure in Camera Raw by the same 1 to 5 stops. In an ideal ISO invariant sensor, all the images should look the same.
The R6 did very well in images underexposed by up to 4 stops. Images underexposed by 5 stops started to fall apart, but I’ve seen that in Sony and Nikon images as well.
Comparing the R6 for ISO Invariancy on a moonlit nightscape.
This behaviour applies to images underexposed by using lower ISOs than what a “normal” exposure might require. Underexposing with lower ISOs can help maintain dynamic range and avoid highlight clipping. But with nightscapes, foregrounds can often be too dark even when shot at an ISO high enough to be suitable for the sky. Foregrounds are almost always underexposed, so good shadow recovery is essential for nightscapes, and especially time-lapses, when blending in separate longer exposures for the ground is not practical.
With its improved ISO invariant sensor, the R6 will be a fine camera for nightscape and time-lapse use, which was not true of the 6D Mark II.
Comparing R6 images underexposed in 1-stop increments by using shorter shutter speeds.Comparing R6 images underexposed in 1-stop increments by using smaller apertures.
However, to be clear, ISO invariant behaviour doesn’t help you as much if you underexpose by using too short a shutter speed or too small a lens aperture. I tested the R6 in series of images underexposed by keeping ISO the same but decreasing the shutter speed then the aperture in one-stop increments.
The underexposed images fell apart in quality much sooner, when underexposed more than 3 stops. Again, this is behaviour similar to what I’ve seen in Sonys and Nikons. For the best image quality I feel it is always a best practice to expose well at the camera. Don’t count on saving images in post.
An in-camera image fairly well exposed with an ETTR histogram.
TIP: Underexposing by using too short an exposure time is the major mistake astrophotographers make, who then wonder why their images are riddled with odd artifacts and patten noise. Always Expose to the Right (ETTR), even with ISO invariant cameras. The best way to avoid noise is to give your sensor more signal, by using longer exposures or wider apertures. Use settings that push the histogram to the right.
LONG EXPOSURE NOISE REDUCTION
All cameras will exhibit thermal noise in long exposures, especially on warm nights. This form of noise peppers the shadows with hot pixels, often brightly coloured.
This is not the same as the shot and read noise that adds graininess to high-ISO images and that noise reduction software can smooth out. This is a common misunderstanding, even among professional photographers who should know better!
Long Exposure Noise Reduction (LENR) eliminates this thermal noise by taking a “dark frame” and subtracting it in-camera to yield a raw file free of hot pixels.
And yes, LENR does apply to raw files, another fact even many professional photographers don’t realize. It is High ISO Noise Reduction that applies only to JPGs, along with Color Space and Picture Styles.
Comparing a dark nightscape without and with LENR on a warm night. Hot pixels are mostly gone at right.
The LENR option on the R6 did eliminate most hot pixels, though sometimes still left, or added, a few. LENR is needed more on warm nights, and with longer exposures at higher ISOs. So the extent of thermal noise in any camera can vary a lot from shoot to shoot.
When LENR is active, the R6’s rear screen lights up with “Busy,” which is annoyingly bright. To hide this display, the only option is to close the screen.
As with the EOS Ra, and all mirrorless cameras, the R6 has no “dark frame buffer” that allows several exposures to be taken in quick succession even with LENR on. Canon’s full-frame DSLRs have this little-known buffer that allows 3, 4, or 5 “light frames” to be taken in a row before the LENR dark frame kicks in a locks up the camera on Busy.
Comparing long exposure images with the lens cap on (dark frames), to show just thermal noise. The right edge of the frame is shown, blown up, to reveal the amp glow, which LENR removes.
With all Canon R cameras, and most other DSLRs, turning on LENR forces the camera to take a dark frame after every light frame, doubling the time it takes to finish every exposure. That’s a price many photographers aren’t willing to pay, but on warm nights it can be necessary, and a best practice, for the reward of cleaner images.
The standard Canon Sensor Cleaning menu.
TIP: If you find hot pixels are becoming more obvious over time, try this trick: turn on the Clean Manually routine for 30 seconds to a minute. In some cameras this can remap the hot pixels so the camera can better eliminate them.
STAR QUALITY
Using LENR with the R6 did not introduce any oddities such as oddly-coloured, green or wiped-out stars. Even without LENR I saw no evidence of green stars, a flaw that plagues some Sony cameras at all times, or Nikons when using LENR.
Comparing the R6 for noise and star colours at typical deep-sky ISOs and exposure times.
Canons have always been known for their good star colours, and the R6 is no exception. According to DPReview the R6 has a low-pass anti-alias filter in front of its sensor. Cameras which lack such a sensor filter do produce sharper images, but stars that occupy only one or two pixels might not de-Bayer properly into the correct colours. That’s not an issue with the R6.
I also saw no “star-eating,” a flaw Nikons and Sonys have been accused of over the years, due to aggressive in-camera noise reduction even on raw files. Canons have always escaped charges of star-eating.
VIGNETTING/SHADOWING
DSLRs are prone to vignetting along the top and bottom of the frame from shadowing by the upraised mirror and mirror box. Not having a mirror, and a sensor not deeply recessed in the body, largely eliminates this edge vignetting in mirrorless cameras.
This illustrates the lack of edge shadows but magenta edge glows in a single Raw file boosted for contrast.
That is certainly true of the R6. Images boosted a lot in contrast, as we do with deep-sky photos, show not the slightest trace of vignetting along the top or bottom edges There were no odd clips or metal bits intruding into the light path, unlike in the Sony a7III I tested in 2018.
The full frame of the R6 can be used without need for cropping or ad hoc edge brightening in post. Except …
EDGE ARTIFACTS/AMP GLOWS
The R6 did exhibit one serious and annoying flaw in long-exposure high-ISO images – a magenta glow along the edges, especially the right edge and lower right corner.
Comparing a close-up of a nightscape, without and with LENR, to show the edge glow gone with LENR on.
Whether this is the true cause or not, it looks like “amplifier glow,” an effect caused by heat from circuitry illuminating the sensor with infra-red light. It shows itself when images are boosted in contrast and brightness in processing. It’s the sort of flaw revealed only when testing for the demands of astrophotography. It was present in images I took through a telescope, so it is not IR leakage from an auto-focus lens.
I saw this type of amp glow with the Sony a7III, a flaw eventually eliminated in a firmware update that, I presume, turned off unneeded electronics in long exposures.
Amp glow is something I have not seen in Canon cameras for many years. In a premium camera like the R6 it should not be there. Period. Canon needs to fix this with a firmware update.
UPDATE AUGUST 1, 2022: As of v1.6 of the R6 firmware, released in July 2022, the amp glow issue remains and has not been fixed. It may never be at this point.
It is the R6’s only serious image flaw, but it’s surprising to see it at all. Turning on LENR eliminates the amp glow, as it should, but using LENR is not always practical, such as in time-lapses and star trails.
For deep-sky photography high-ISO images are pushed to extremes of contrast, revealing any non-uniform illumination or colour. The usual practice of taking and applying calibration dark frames should also eliminate the amp glow. But I’d rather it not be there in the first place!
RED SENSITIVITY
The R6 I bought was a stock “off-the-shelf” model. It is Canon’s now-discontinued EOS Ra model that is (or was) “filter-modified” to record a greater level of the deep red wavelength from red nebulas in the Milky Way. Compared to the Ra, the R6 did well, but could not record the depth of nebulosity the Ra can, to be expected for a stock camera.
Comparing the stock R6 with the filter-modified Ra on Cygnus nebulosity.
In wide-field images of the Milky Way, the R6 picked up a respectable level of red nebulosity, especially when shooting through a broadband light pollution reduction filter, and with careful processing.
Comparing the stock R6 with the filter-modified Ra on the Swan Nebula with a telescope with minimal processing to the Raw images.Comparing the stock R6 with the filter-modified Ra on the Swan Nebula with a telescope with a dual narrowband filter and with colour correction applied to the single Raw images.
However, when going after faint nebulas through a telescope, even the use of a narrowband filter did not help bring out the target. Indeed, attempting to correct the extreme colour shift introduced by such a filter resulted in a muddy mess and accentuated edge glows with the R6, but worked well with the Ra.
While the R6 could be modified by a third party, the edge amp glow might spoil images, as a filter modification can make a sensor even more sensitive to IR light, potentially flooding the image with unwanted glows.
TIP: Buying a used Canon Ra (if you can find one) might be one choice for a filter-modified mirrorless camera, one much cheaper than a full frame cooled CMOS camera such as a ZWO ASI2400MC. Or Spencer’s Camera sells modified versions of all the R series cameras with a choice of sensor filters. But I have not used any of their modded cameras.
RESOLUTION
A concern of prospective buyers is whether the R6’s relatively low 20-megapixel sensor will be sharp enough for their purposes. R6 images are 5472 by 3648 pixels, much less than the 8000+ pixel-wide images from high-resolution cameras like the Canon R5, Nikon Z7II or Sony a1.
Unless you sell your astrophotos as very large prints, I’d say don’t worry. In comparisons with the 30-megapixel Ra I found it difficult to see a difference in resolution between the two cameras. Stars were nearly as well resolved in the R6, and only under the highest pixel-peeping magnification did stars look a bit more pixelated in the R6 than in the Ra. Faint stars were equally well recorded.
Comparing resolution of the R6 vs. Ra with a blow-up of wide-field 85mm imagesComparing resolution of the R6 vs. Ra on blow-ups of the Andromeda Galaxy with a 76mm apo refractor. The R6 is more pixellated but it takes pixel peeping to see it!
The difference between 20 and 30 megapixels is not as great as you might think for arc-second-per-pixel plate scale. I think it would take going to the R5 with its 45 megapixel sensor to provide enough of a difference in resolution over the R6 to be obvious in nightscape scenes, or when shooting small, detailed deep-sky subjects such as globular clusters.
If landscape or wildlife photography by day is your passion, with astrophotography a secondary purpose, then the more costly but highly regarded R5 might be the better choice.
Super Resolution menu in Adobe Lightroom.
TIP: Adobe now offers (in Lightroom and in Camera Raw) a Super Resolution option, that users might think (judging by the rave reviews on-line) would be the answer to adding resolution to astro images from “low-res” cameras like the R6.
Comparing a normal R6 image with the same image upscaled with Super Resolution.
Sorry! In my tests on astrophotos I’ve found Super Resolution results unsatisfactory. Yes, stars were less pixelated, but they became oddly coloured in the AI-driven up-scaling. Green stars appeared! The sky background also became mottled and uneven.
I would not count on such “smart upscaling” options to add more pixels to astro-images from the R6. Then again, I don’t think there’s a need to.
RAW vs. cRAW
Canon now offers the option of shooting either RAW or cRAW files, the latter being the same megapixel count but compressed in file size by almost a factor of two. This allows shooting twice as many images before card space runs out, perhaps useful for shooting lots of time-lapses on extended trips away from a computer.
The R6 Image Quality menu with the cRAW Option.Comparing an R6 cRAW with a RAW image.
However, the compression is not lossless. In high-ISO test images purposely underexposed, then brightened in post, I could see a slight degradation in cRAW images – the noise background looked less uniform and exhibited a blocky look, like JPG artifacts.
The R6’s dual SD card slots.
TIP: With two SD card slots in the R6 (the second card can be set to record either a backup of images on card one, or serve as an overflow card) and the economy of large SD cards, there’s not the need to conserve card space as there once was. I would suggest always shooting in the full RAW format. Why accept any compression and loss of image quality?
BATTERY LIFE
The R6 uses a new version of Canon’s standard LP-E6 battery, the LP-E6NH, that supports charging through the USB-C port and has a higher 2130mAh capacity than the 1800mAh LP-E6 batteries. However, the R6 is compatible with older batteries.
On warm nights, I found the R6 ran fine on one battery for the 3 to 4 hours needed to shoot a time-lapse sequence, with power to spare. However, as noted below, the lack of a top LCD screen means there’s no ongoing display of battery level, a deficiency for time-lapse and deep-sky work.
For demanding applications, especially in winter, the R6 can be powered by an outboard USB power bank that has “Power Delivery” capability. That’s a handy feature. There’s no need to install a dummy battery leading out to a specialized power source.
The R6’s Connection menu with Airplane mode to turn off battery-eating WiFi and Bluetooth.
TIP: Putting the camera into Airplane mode (to turn off WiFi and Bluetooth), turning off the viewfinder, and either switching off or closing the rear screen all helps conserve power. The R6 does not have GPS built in. Tagging images with location data requires connecting to your phone.
VIDEO USE
A major selling point for me was the R6’s low-light video capability. It replaces my Sony A7III, which had been my “go to” camera for real-time 4K movies of auroras.
As best I can tell (from the dimmer auroras I’ve shot to date), the R6 performs equally as well as the Sony. It is able to record good quality (i.e. acceptably noise-free) 4K movies at ISO 25,600 to ISO 51,200. While it can shoot at up to ISO 204,800, the excessive noise makes the top ISO an emergency-use only setting.
The R6’s Movie size and quality options, with 4K and Full HD formats and frame rates.
Comparing the R6 on a dim aurora at various high ISO speeds. Narrated at the camera — excuse the wind noise! Switch to HD mode for the best video playback quality. This was shot in 4K but WordPress plays back only in HD.
The R6 can shoot at a dragged shutter speed as slow as 1/8-second – good, though not as slow as the Sony’s 1/4-second slowest shutter speed in movie mode. That 1/8-second shutter speed and a fast f/1.4 to f/2 lens are the keys to shooting movies of the night sky. Only when auroras get shadow-casting bright can we shoot at the normal 1/30-second shutter speed and at lower ISOs.
As with Nikons (but not Sonys), the Canon R6 saves its movie settings separately from its still settings. When switching to Movie mode you don’t have to re-adjust the ISO, for example, to set it higher than it might have been for stills, very handy for taking both stills and movies of an active aurora, where quick switching is often required.
Unlike the R and Rp, the R6 captures 4K movies from the full width of the sensor, preserving the field of view of wide-angle lenses. This is excellent for aurora shooting.
The R6’s Movie Cropping menu option
A 4K movie of the Moon in full-frame and copped-frame modes, narrated at the camera. Again, this was shot in 4K but WordPress plays back only in HD.Comparing blow-ups of frame-grabbed stills from a full-frame 4K vs. Cropped frame 4K. The latter is less pixellated.
However, the R6 offers the option of a “Movie Crop” mode. Rather than taking the 4K movie downsampled from the entire sensor, this crop mode records from a central 1:1 sampled area of the sensor. That mode can be useful for high-magnification lunar and planetary imaging, for ensuring no loss of resolution. It worked well, producing videos with less pixelated fine details in test movies of the Moon.
Though of course I have yet to test it on one, the R6 should be excellent for movies of total solar eclipses. It can shoot 4K up to 60 frames per second in both full frame and cropped frame. It cannot shoot 6K (buy the R3!) or 8K (buy the R5!).
The R6’s Canon Log settings menu for video files.
Shooting in the R6’s Canon cLog3 profile records internally in 10-bit, preserving more dynamic range in movies, up to 12 stops. During eclipses, that will be a benefit for recording totality, with the vast range of brightness in the Sun’s corona. It should also aid in shooting auroras which can vary over a huge range in brightness.
Grading a cLog format movie in Final Cut under Camera LUT.
TIP: Processing cLog movies, which look flat out of camera, requires applying a cLog3 Look Up Table, or LUT, to the movie clips in editing, a step called “colour grading.” This is available from Canon, from third-party vendors or, as it was with my copy of Final Cut Pro, might be already installed in your video editing software. When shooting, turn on View Assist so the preview looks close to what the final graded movie will look like.
EXPOSURE TRACKING IN TIME-LAPSES
In one test, I shot a time-lapse from twilight to darkness with the R6 in Aperture Priority auto-exposure mode, of a fading display of noctilucent clouds. I just let the camera lengthen the shutter speed on its own. It tracked the darkening sky very well, right down to the camera’s maximum exposure time of 30 seconds, using a fish-eye lens at f/2.8. This demonstrated that the light meter in the R6 was sensitive enough to work well in dim light.
Other cameras I have used cannot do this. The meter fails at some point and the exposure stalls at 5 or 6 seconds long, resulting in most frames after that being underexposed. By contrast, the R6 showed excellent performance, negating the need for special bulb ramping intervalometers for some “holy grail” scenes. Here’s the resulting movie.
A time-lapse of 450 frames from 0.4 seconds to 30 seconds, with the R6 in Av mode. Set to 1080P for the best view! A screenshot from LRTimelapse showing the smoothness of the exposure tracking (the blue line) through the sequence,
In addition, the R6’s exposure meter tracked the darkening sky superbly, with nary a flicker or variation. Again, few cameras can do this. Nikons have an Exposure Smoothing option in their Interval Timers which works well.
The R6 has no such option but doesn’t seem to need it. The exposure did fail at the very end, when the shutter reached its maximum of 30 seconds. If I had the camera on Auto ISO, it might have started to ramp up the ISO to compensate, a test I have yet to try. Even so, this is impressive time-lapse performance in auto-exposure.
MISSING FEATURES
The R6, like the low-end Rp, lacks a top LCD screen for display of camera settings and battery level. In its place we get a traditional Mode dial, which some daytime photographers will prefer. But for astrophotography, a backlit top LCD screen provides useful information during long exposures.
The R6 top and back of camera view.
Without it, the R6 provides no indication of battery level while a shoot is in progress, for example, during a time-lapse. A top screen is also useful for checking ISO and other settings by looking down at the camera, as is usually the case when it’s on a tripod or telescope.
The lack of a top screen is an inconvenience for astrophotography. We are forced to rely on looking at the brighter rear screen for all information. It is a flip-out screen, so can be angled up for convenient viewing on a telescope.
The R6’s flip screen, similar to most other new Canon cameras.
The R6 has a remote shutter port for an external intervalometer, or control via a time-lapse motion controller. That’s good!
However, the port is Canon’s low-grade 2.5mm jack. It works, and is a standard connector, but is not as sturdy as the three-pronged N3-style jack used on Canon’s 5D and 6D DSLRs, and on the R3 and R5. Considering the cost of the R6, I would have expected a better, more durable port. The On/Off switch also seems a bit flimsy and easily breakable under hard use.
The R6’s side ports, including the remote shutter/intervalometer port.
These deficiencies provide the impression of Canon unnecessarily “cheaping out” on the R6. You can forgive them with the Rp, but not with a semi-professional camera like the R6.
INTERVAL TIMER
Unlike the Canon R and Ra (which still mysteriously lack a built-in interval timer, despite firmware updates), the R6 has one in its firmware. Hurray! This can be used to set up a time-lapse sequence, but on exposures only up to the maximum of 30 seconds allowed by the camera’s shutter speed settings, true of most in-camera intervalometers.
The Interval Timer menu page.
For 30-second exposures taken in succession as quickly as possible the interval on the R6 has to be set to 34 seconds. The reason is that the 30-second exposure is actually 32 seconds, true of all cameras. With the R6, having a minimum gap in time between shots requires an Interval not of 33 seconds as with some cameras, but 34 seconds. Until you realize this, setting the intervalometer correctly can be confusing.
Like all Canon cameras, the R6 can be set to take only up to 99 frames, not 999. That seems a dumb deficiency. Almost all time-lapse sequences require at least 200 to 300 frames. What could it possibly take in the firmware to add an extra digit to the menu box? It’s there at in the Time-lapse Movie function that assembles a movie in camera, but not here where the camera shoots and saves individual frames. It’s another example where you just can’t fathom Canon’s software decisions.
Setting the Interval Timer for rapid sequence shots with a 30-second exposure.
TIP: If you want to shoot 100 or more frames, set the Number of Frames to 00, so it will shoot until you tell the camera to stop. But awkwardly, Canon says the way to stop an interval shoot is to turn off the camera! That’s crude, as doing so can force you to refocus if you are using a Canon RF lens. Switching the Mode dial to Bulb will stop an interval shoot, an undocumented feature.
BULB TIMER
As with most recent Canon DSLRs and DSLMs, the menu also includes a Bulb Timer. This allows setting an exposure of any length (many minutes or hours) when the camera is in Bulb mode. This is handy for single long shots at night.
The Bulb Timer menu page. Bulb Timer only becomes an active choice when the camera is on Bulb.
However, it cannot be used in conjunction with the Interval Timer to program a series of multi-minute exposures, a pity. Instead, a separate outboard intervalometer has to be used for taking an automatic set of any exposures longer than 30 seconds, true of all Canons.
In Bulb and Bulb Timer mode, the R6’s rear screen lights up with a bright Timer readout. While the information is useful, the display is too bright at night and cannot be dimmed, nor turned red for night use, exactly when you are likely to use Bulb. The power-saving Eco mode has no effect on this display, precisely when you would want it to dim or turn off displays to prolong battery life, another odd deficiency in Canon’s firmware.
The Bulb Timer screen active during a Bulb exposure. At night it is bright!
The Timer display can only be turned off by closing the flip-out screen, but now the viewfinder activates with the same display. Either way, a display is on draining power during long exposures. And the Timer readout lacks any indication of battery level, a vital piece of information during long shoots. The Canon R, R3 and R5, with their top LCD screens, do not have this annoying “feature.”
TIP: End a Bulb Timer shoot prematurely by hitting the Shutter button. That feature is documented.
IN-CAMERA IMAGE STACKING
The R6 offers a menu option present on many recent Canon cameras: Multiple Exposure. The camera can take and internally stack up to 9 images, stacking them by using either Average (best for reducing noise) or Bright mode (best for star trails). An Additive mode also works for star trails, but stacking 9 images requires reducing the exposure of each image by 3 stops, say from ISO 1600 to ISO 200, as I did in the example below.
The Multiple Exposure menu page.
The result of the internal stacking is a raw file, with the option of also saving the component raws. While the options work very well, in all the cameras I’ve owned that offer such functions, I’ve never used them. I prefer to do any stacking needed later at the computer.
Comparing a single image with a stack of 9 exposures with 3 in-camera stacking methods.
TIP: The in-camera image stacking options are good for beginners wanting to get advanced stacking results with a minimum of processing fuss later. Use Average to stack ground images for smoother noise. Use Bright for stacking sky images for star trails. Activate one of those modes, then control the camera with a separate intervalometer to automatically shoot and internally stack several multi-minute exposures.
SHUTTER OPERATION
Being a mirrorless camera, there is no reflex mirror to introduce vibration, and so no need for a mirror lockup function. The shutter can operate purely mechanically, with physical metal curtains opening and closing to start and end the exposure.
However, the default “out of the box” setting is Electronic First Curtain, where the actual exposure, even when on Bulb, is initiated electronically, but ended by the mechanical shutter. That’s good for reducing vibration, perhaps when shooting the Moon or planets through a telescope at high magnification.
R6 Shutter Mode options.
In Mechanical, the physical curtains both start and end the exposure. It’s the mode I usually prefer, as I like to hear the reassuring click of the shutter opening. I’ve never found shutter vibration a problem when shooting deep sky images on a telescope mount of any quality.
In Mechanical mode the shutter can fire at up to 12 frames a second, or up to 20 frames a second in Electronic mode where both the start and end of the exposure happen without the mechanical shutter. That makes for very quiet operation, good for weddings and golf tournaments!
Electronic Shutter Mode is for fastest burst rates but has limitations.
Being vibration free, Electronic shutter might be great during total solar eclipses for rapid-fire bursts at second and third contacts when shooting through telescopes. Maximum exposure time is 1/2 second in this mode, more than long enough for capturing fleeting diamond rings.
Longer exposures needed for the corona will require Mechanical or Electronic First Curtain shutter. Combinations of shutter modes, drive rates (single or continuous), and exposure bracketing can all be programmed into the three Custom Function settings (C1, C2 and C3) on the Mode dial, for quick switching at an eclipse. It might not be until April 8, 2024 until I have a chance to test these features. And by then the R6 Mark II will be out!
TIP: While the R6’s manual doesn’t state it, some reviews mention (including at DPReview) that when the shutter is in fully Electronic mode the R6’s image quality drops from 14-bit to 12-bit, true of most other mirrorless cameras. This reduces dynamic range. I would suggest not using Electronic shutter for most astrophotography, even for exposures under 1/2 second. For longer exposures, it’s a moot point as it cannot be used.
The menu option that fouls up all astrophotographers using an R-series camera.
TIP: The R6 has the same odd menu item that befuddles many a new R-series owner, found on Camera Settings: Page 4. “Release Shutter w/o Lens” defaults to OFF, which means the camera will not work if it is attached to a manual lens or telescope it cannot connect to electronically. Turn it ON and all will be solved. This is a troublesome menu option that Canon should eliminate or default to ON.
OTHER MENU FEATURES
The rear screen is fully touch sensitive, allowing all settings to be changed on-screen if desired, as well as by scrolling with the joystick and scroll wheels. I find going back to an older camera without a touchscreen annoying – I keep tapping the screen expecting it to do something!
The Multi-Function Button brings up an array of 5 settings to adjust. This is ISO.
The little Multi-Function (M-Fn) button is a worth getting used to, as it allows quick access to a choice of five important functions such as ISO, drive mode and exposure compensation. However, the ISO, aperture and shutter speed are all changeable by the three scroll wheels.
The Q button brings up the Quick Menu for displaying and adjusting key functions.
There’s also the Quick menu activated by the Q button. While the content of the Quick menu screen can’t be edited, it does contain a good array of useful functions, adjustable with a few taps.
Under Custom settings, the Dials and Buttons can be re-assigned to other functions.
Unlike Sonys, the R6 has no dedicated Custom buttons per se. However, it does offer a good degree of customization of its buttons, by allowing users to re-assign them to other functions they might find more useful than the defaults. For example ….
This shows the AF Point button being re-assigned to the Maximize Screen Brightness (Temporary) command.
I’ve taken the AF Point button and assigned it to the Maximize Screen Brightness function, to temporarily boost the rear screen to full brightness for ease of framing.
The AE Lock button I assigned to switch the Focus Peaking indicators on and off, to aid manual focusing when needed.
The Depth of Field Preview button I assigned to switching between the rear screen and viewfinder, through that switch does happen automatically as you put your eye to the viewfinder.
The Set button I assigned to turning off the Rear Display, though that doesn’t have any effect when the Bulb Timer readout is running, a nuisance.
While the physical buttons are not illuminated, having a touch screen makes it less necessary to access buttons in the dark. It’s a pity the conveniently positioned but mostly unused Rate button can’t be re-programmed to more useful functions. It’s a waste of a button.
Set up the Screen Info as you like it by turning on and off screen pages and deciding what each should show.
TIP: The shooting screens, accessed by the Info button (one you do need to find in the dark!), can be customized to show a little, a lot, or no information, as you prefer. Take the time to set them up to show just the information you need over a minimum of screen pages.
LENS AND FILTER COMPATIBILITY
The new wider RF mount accepts only Canon and third-party RF lenses. However, all Canon and third-party EF mount lenses (those made for DSLRs) will fit on RF-mount bodies with the aid of the $100 Canon EF-to-RF lens adapter.
The Canon ER-to-RF lens adapter will be needed to attach R cameras to most telescope camera adapters and Canon T-rings made for older DSLR cameras.
This adapter will be necessary to attach any Canon R camera to a telescope equipped with a standard Canon T-ring. That’s especially true for telescopes with field flatterers where maintaining the standard 55mm distance between the flattener and sensor is critical for optimum optical performance.
The shallower “flange distance” between lens and sensor in all mirrorless cameras means an additional adapter is needed not just for the mechanical connection to the new style of lens mount, but also for the correct scope-to-sensor spacing.
The extra spacing provided by a mirrorless camera has the benefit of allowing a filter drawer to be inserted into the light path. Canon offers a $300 lens adapter with slide-in filters, though the choice of filters useful for astronomy that fit Canon’s adapter is limited. AstroHutech offers a few IDAS nebula filters.
Clip-in filters made for the EOS R, such as those offered by Astronomik, will also fit the R6. Though, again, most narrowband filters will not work well with an unmodified camera.
The AstroHutech adapter allows inserting filters into the light path on telescopes.
TIP: Alternatively, AstroHutech also offers its own lens adapter/filter drawer that goes from a Canon EF mount to the RF mount, and accepts standard 52mm or 48mm filters. It is a great way to add interchangeable filters to any telescope when using an R-series camera, while maintaining the correct back-focus spacing. I use an AstroHutech drawer with my Ra, where the modified camera works very well with narrowband filters. Using such filters with a stock R6 won’t be as worthwhile, as I showed above.
A trio of Canon RF zooms — all superb but quite costly.
As of this writing, the selection of third-party lenses for the Canon RF mount is limited, as neither Canon or Nikon have “opened up” their system to other lens makers, unlike Sony with their E-mount system. For example, we have yet to see much-anticipated RF-mount lenses from Sigma, Tamron and Tokina.
A trio of third party RF lenses — L to R: the TTArtisan 7.5mm f/2 and 11mm f/2.8 fish-eyes and the Samyang/Rokinon AF 85mm f/1.4.
The few third-party lenses that are available, from TTArtisan, Venus Optics and other boutique Chinese lens companies, are usually manual focus lenses with reverse-engineered RF mounts offering no electrical contact with the camera. Some of these wide-angle lenses are quite good and affordable. (I tested the TTArtisan 11mm fish-eye here.)
Until other lens makers are “allowed in,” if you want lenses with auto-focus and camera metadata connections, you almost have to buy Canon. Their RF lenses are superb, surpassing the quality of their older EF-mount equivalents. But they are costly. I sold off a lot of my older lenses and cameras to help pay for the new Canon glass!
Astrophotographers often like to operate their cameras at the telescope using computers running specialized control software. I tested the R6 with two popular Windows programs for controlling DSLR and now mirrorless cameras, BackyardEOS (v3.2.2) and AstroPhotographyTool (v3.88). Both recognized and connected to the R6 via its USB port.
Both programs recognized the Canon R6.
Another popular option is the ASIair WiFi controller from ZWO. It controls cameras via one of the ASIair’s USB ports, and not (confusingly) through the Air’s remote shutter jack marked DSLR. Under version 1.7 of its mobile app, the ASIair now controls Canon R cameras and connected to the R6 just fine, allowing images to be saved both to the camera and to the Air’s own MicroSD card.
With an update in 2021, the ZWOASIair now operates Canon R-series cameras.
The ASIair is an excellent solution for both camera control and autoguiding, with operation via a mobile device that is easier to use and power in the field than a laptop. I’ve not tried other hardware and software controllers with the R6.
TIP: While the R6, like many Canon cameras, can be controlled remotely with a smartphone via the CanonConnect mobile app, the connection process is complex and the connection can be unreliable. The Canon app offers no redeeming features for astrophotography, and maintaining the connection via WiFi or Bluetooth consumes battery power.
A dim red and green aurora from Dinosaur Provincial Park, Alberta, on August 29/30, 2021. This is a stack of 4 exposures for the ground to smooth noise and one exposure for the sky, all 30 seconds at f/2.8 with the Canon 15-35mm RF lens at 25mm and the Canon R6 at ISO 4000.
SUGGESTIONS TO CANON
To summarize, in firmware updates, Canon should:
Fix the low-level amp glow. No camera should have amp glow.
Allow either dimming the Timer readout, turning it red, or just turning it off!
Add a battery display to the Timer readout.
Expand the Interval Timer to allow up to 999 frames, as in the Time-Lapse Movie.
Allow the Rate button to be re-assigned to more functions.
Default the Release Shutter w/o Lens function to ON.
Revise the manual to correctly describe how to stop an Interval Timer shoot.
Allow programming multiple long exposures by combining Interval and Bulb Timer, or by expanding the shutter speed range to longer than 30 seconds, as some Nikons can do.
The Zodiacal Light in the dawn sky, September 14, 2021, from home in Alberta, with the winter sky rising. This is a stack of 4 x 30-second exposures for the ground to smooth noise, and a single 30-second exposure for the sky, all with the TTArtisan 7.5mm fish-eye lens at f/2 and on the Canon R6 at ISO 1600.
CONCLUSION
The extended red sensitivity of the Canon EOS Ra makes it better suited for deep-sky imaging. But with it now out of production (Canon traditionally never kept its astronomical “a” cameras in production for more than two years), I think the R6 is now Canon’s best camera (mirrorless or DSLR) for all types of astrophotography, both stills and movies.
However, I cannot say how well it will work when filter-modified by a third-party. But such a modification is necessary only for recording red nebulas in the Milky Way. It is not needed for other celestial targets and forms of astrophotography.
A composite showing about three dozen Perseid meteors accumulated over 3 hours of time, compressed into one image showing the radiant point of the meteor shower in Perseus. All frames were with the Canon R6 at ISO 6400 and with the TTArtisan 11mm fish-eye lens at f/2.8.
The low noise and ISO invariant sensor of the R6 makes it superb for nightscapes, apart from the nagging amp glow. That glow will also add an annoying edge gradient to deep-sky images, best dealt with when shooting by the use of LENR or dark frames.
As the image of the Andromeda Galaxy, M31, at the top of the blog attests, with careful processing it is certainly possible to get fine deep-sky images with the R6.
For low-light movies the R6 is Canon’s answer to the Sony alphas. No other Canon camera can do night sky movies as well as the R6. For me, it was the prime feature that made the R6 the camera of choice to complement the Ra.
It’s been a marvelous few months following Venus rise and fall across the evening sky, in its best show in eight years.
Venus is now gone from our western sky, but since late 2019 until late May 2020 it had dominated the sky as a brilliant evening star.
Here’s a gallery of Venus portraits I shot during its wonderful show these last few months.
The show began in November 2019 when rising Venus met declining Jupiter on November 23 for a fine conjunction of the two brightest planets in the evening twilight.
The conjunction of Venus and Jupiter of November 23, 2019, as seen over the foothills and front ranges of the Rocky Mountains in southwest Alberta. I shot this from the Rothney Astrophysical Observatory, prior to their monthly Open House event that night with about 400 in attendance. But at this time it was just me and one other ardent photographer present to shoot this scene. This is an HDR blend (stacked using Adobe Camera Raw) of 5 exposures at 2/3-stop intervals, with the Rokinon 85mm lens at f/4 on the red-sensitive Canon EOS Ra camera at ISO 100.
A week later I captured the line of the then three evening planets and the Moon across the southwest, defining the path of the ecliptic across the evening sky.
The waxing crescent Moon and three planets in a line across the southwestern evening sky on Nov. 30, 2019, a chilly and frosty night. Saturn is below and to the right of the Moon, Venus is brightest at centre, while Jupiter is to the lower right of Venus just above the horizon. Those two planets were in conjunction a week earlier. The line of Moon and planets visibly defines the ecliptic low across the late autumn evening sky. This is from latitide 51° N. I shot this from the viewpoint at Blackfoot Crossing overlooking the Bow River in Alberta.
A week after that I took the opportunity to shoot some selfies of me with binoculars looking at Venus, as it met Saturn in a wide conjunction, with Venus then still low in the southwest. It was just beginning its climb up into the western sky.
A selfie of me observing the grouping of Venus and Saturn in the evening twilight on Dec 8, 2019, using binoculars. They were closest to each other two nights later.
A month later in mid-winter, Venus was still rather low but brilliant even in a hazy moonlit sky, as I posed for another selfie, this time with a small telescope. These images are always useful for illustrations in books and magazines. And blogs!
A selfie of me observing Venus in clouds and in the moonlight. I am using the Explore Scientific 80mm refractor on the Twilight Nano alt-az mount. This was January 9, 2020.
By the end of February Venus had climbed high into the west, and was appearing monthly near the waxing crescent Moon. This is another binocular selfie from February 27.
A selfie looking at the waxing crescent Moon near Venus on Feb 27, 2020, using the Celestron SkyMaster 15×70 Pro binoculars on the Sky-Watcher AZ5 mount for a steady view. This is a single shot with the Nikon D750 and Sigma 24mm lens, using the flash on the camera.
In March I visited Churchill, Manitoba just as the lockdown and travel restrictions were coming into effect. But our lone and last tour group at the Churchill Northern Studies Centre saw some fine auroras, as here on this evening with the Northern Lights appearing even in the twilight. And what’s that bright star? Venus, of course!
The Northern Lights in the evening twilight on March 18, 2020, as the aurora appeared in the early evening sky. Orion is at far left in this panorama, with Cassiopeia at top centre. Part of the Big Dipper is at far right. The bright object over the Centre is Venus, with the Pleiades above. This is a panorama of 8 segments with the Venus Optics 15mm lens at f/2 and Sony a7III at ISO 800 for 1.6 seconds each. Stitched with Photoshop.
Upon my return home to Alberta, I was able to shoot more panoramas on the prairies of the wonderful early spring sky with Orion setting into the twilight and Venus in Taurus shining below the iconic Pleiades star cluster.
This is a panorama of the evening sky on March 25, 2020, with brilliant Venus high in the west at centre just after the date (March 24) of its greatest elongation in the evening sky for 2020. It appears here about as high as it can get with the ecliptic tipped up to a high angle in spring. To the left is Orion and the winter stars in the twilight, including Sirius at far left. Just above the horizon right of centre in the bright twilight is the day-old thin crescent Moon about to set. Above Venus are the Pleiades and Hyades star clusters. This is a panorama of 5 segments with the Nikon D750 and 24mm Sigma lens, stitched with PTGui. Each segment was 8 seconds at ISO 400 and f/2.8.
March 26 was a superb night for catching Venus now at its highest and almost at its brightest at this appearance, as the waxing Moon appeared below it.
The evening scene on March 26, 2020 of the setting waxing crescent Moon below Venus which is below the Pleiades star cluster. At top centre is the Hyades star cluster and Aldebaran in Taurus. At left is Orion sinking into the twilight of a spring evening. The setting is the old farmstead near home.
This is a stack of 7 exposures for the ground to smooth noise, and one for the sky, all 10 seconds at f/2.8 with the 24mm Sigma lens and Nikon D750 at ISO 400.
The waxing crescent Moon with Earthshine and (above) Venus shine in the evening twilight sky over an icy pond near home, on March 26, 2020. Venus was just past greatest elongation from the Sun, and being spring with the high angle of the ecliptic, Venus was as high as it can get this year in an evening apparition. The Pleiades is at very top.
This is a stack of 7 exposures for the ground to smooth noise and one for the sky, all 2.5 seconds at f.4 with the Sigma 24mm lens and Nikon D750 at ISO 200.
The highlight of the spring Venus season was its close approach to the Pleiades, which it passes only every 8 years. Here I am viewing the conjunction two days before the closest approach, with Orion over my shoulder.
A selfie of me viewing the close approach of Venus to the Pleiades star cluster on April 1, 2020, using big 15×70 Celestron SkyMaster Pro binoculars mounted on a Canadian-built Starlight Innovations binocular mount, a parallelogram-style mount. Orion is over my left shoulder; the Hyades is at centre above the mount. The waxing gibbous Moon provided the illumination. This is a stack of 4 images for the ground to smooth noise and 1 image for the sky to minimize trailing, all 13 seconds at f/5.6 with the Sigma 24mm lens and Nikon D750 at ISO 1600. Topaz Sharpen AI and DeNoise AI applied.
The night of closest approach, April 3, was cloudy, but here is a consolation closeup taken the next night with brilliant Venus departing the Seven Sisters.
Venus above the Pleiades star cluster, M45, on April 4, 2020, in the twilight and moonlight. Light from the gibbous Moon illuminated the sky, so no long exposure would reveal much detail in and around the Pleiades. Venus passes close to the Pleiades only every 8 years. Some light cloud this night added the glow. This is a stack of multiple exposures of varying lengths: 2 minutes, 30 seconds, 10 seconds and 2 seconds, blended with masks to prevent Venus from being too blown out while still recording the stars. All were with the SharpStar 140mm PH apo refractor with the 0.73x flattener/reducer for f/4.8 and at ISO 400 with the Canon EOS Ra.
Later in April Venus reached its greatest brilliancy, at magnitude -4.7, the date when the size of is disk, phase, and proximity to Earth converge to make Venus as bright as possible. On this night I shot the Moon, then 30° away from Venus and the planet with the same gear to show their relative sizes and similar crescent phase this night. The caption provides more details.
A collage of two images of the Moon and Venus taken minutes apart on April 28, 2020, to show the similarity in their phases this night, April 28, 2020. Both images were shot with the same focal length and camera and so are identical in image scale, to compare their apparent sizes. I have not enlarged Venus, but I have put a frame around it to emphasize that its image has been layered in as a composite. The Moon was a 5.6-day-old waxing crescent this night, 32% illuminated. Venus was at its greatest brilliancy, or Greatest Illuminated Extent, with a disk 38 arc seconds across and 27% illuminated, so slightly less. Taken with the 130mm Astro-Physics refractor with a 2X Barlow lens for an effective focal length of 1600mm and with the Canon 60Da APS-sensor camera. The Moon image is the full frame of the sensor, uncropped. Both images are single short exposures at ISO 100.
A week later, with Venus just past its point of greatest brilliancy, I shot the planet by daylight in the early evening sky, using a telescope to zoom into the planet to show its waning crescent phase. By this time the phase was obvious in binoculars.
Venus in the daytime sky and through some thin clouds, on May 5, 2020, with Venus at a very high apparition. This was at about 7 pm with the Sun still well up in the early evening, to show how well Venus can be seen in the daytime sky when it is at a wider angle from the Sun; and indeed is often the best time to view it as the planet’s brilliance is muted. This is a single 1/400-second exposure at ISO 100 with the Canon 60Da through the Astro-Physics 130mm refractor and 2X Barlow for f/12 and 1600mm focal length.
But Venus was now dropping rapidly from sight. By May 23, it was low in the twilight and below Mercury, then at its best for 2020 for an evening appearance from my latitude. Note the thin Moon below the planets. This was a superb sight for binoculars.
On May 23, 2020, the very thin crescent Moon (then 34 hours old) shines below bright Venus (10 days before its inferior conjunction with the Sun) and above it dimmer Mercury , then 10 days before its greatest elongation from the Sun in the evening sky. All were beautifully visible to the naked eye and a great sight in binoculars, looking very much like this scene captured with a 135mm telephoto lens. Venus was magnitude -4.4, Mercury was -0.7. This is a single shot at f/2.8 and 1/ 5 second at ISO 100 with the Canon EOS Ra which does bring out the sunset reds well.
By May 29, Venus was now tough to pick out of the evening sky, and a challenge to shoot even by day, as it then stood only 8° away from the Sun. What was once obvious to the naked eye now took a computerized telescope to pick out of the noon-day blue sky. A telescope showed the now razor-thin crescent as Venus approached its June 3 “inferior conjunction” — its passage between Earth and the Sun.
Venus as a razor-thin crescent and only 8° east of the Sun on May 29, 2020, five days before its June 3 inferior conjunction. The crescent is extending a little beyond 180° here due to scattering in the Venusian clouds. The disk was 57 arc seconds across and 0.9% illuminated. The magnitude was -3.9. This was at midday, shot with the 130mm Astro-Physics f/6 refractor with a 2X Barlow and the Canon 60Da camera, but the frame cropped further in processing. This is a single 1/1250th second exposure at ISO 100, the sharpest of 70 still frames taken.
I shot and narrated video footage of the thin crescent Venus, my parting shots of Venus for its evening appearance in 2020.
But in June, post inferior conjunction, it will rise very quickly into our morning sky, providing a mirror-image repeat performance as a morning star for the rest of 2020.
Venus Near Inferior Conjunction from Alan Dyer on Vimeo.
I wish you all the best and a safe and healthy time in 2020. Take some solace in what the sky can show us and in the beauty of the night.
I had the chance to test out an early sample of Canon’s new EOS Ra camera designed for deep-sky photography.
Once every 7 years astrophotographers have reason to celebrate when Canon introduces one of their “a” cameras, astronomical variants optimized for deep-sky objects, notably red nebulas.
In 2005 Canon introduced the ground-breaking 8-megapixel 20Da, the first DLSR to feature Live View for focusing. Seven years later, in 2012, Canon released the 18-megapixel 60Da, a camera I still use and love.
Both cameras were cropped-frame DSLRs.
Now in 2019, seven years after the 60Da, we have the newly-released EOS Ra, the astrophoto version of the 30-megapixel EOS R released in late 2018. The EOS R is a full-frame mirrorless camera with a sensor similar to what’s in Canon’s 5D MkIV DSLR.
Here, I present a selection of sample images taken with the new EOS Ra.
The large emission nebula IC 1805 in Cassiopeia, aka the Heart Nebula. The round nebula at top right is NGC 896. The large loose star cluster at centre is Mel 15; the star cluster at left is NGC 1027. The small cluster below NGC 896 is Tombaugh 4. This is a stack of 8 x 6-minute exposures with the Canon EOS Ra mirrorless camera at ISO 1600 through the Astro-Physics Traveler apo refractor at f/6 with the Hotech field flattener. Stacked, aligned and processed in Photoshop.
Both versions of the EOS R have identical functions and menus.
The big difference is that the EOS Ra, as did Canon’s earlier “a” models, has a factory-installed filter in front of the sensor that transmits more of the deep red “hydrogen-alpha” wavelength emitted by glowing nebulas.
Normal cameras suppress much of this deep-red light as a by-product of their filters cutting out the infra-red light that digital sensors are very sensitive to, but that would not focus well.
The North America Nebula, NGC 7000, in Cygnus, taken with the new Canon EOS Ra factory-modified “astronomical” version of the Canon EOS R mirrorless camera. This is a stack of 4 x 6-minute exposures, with LENR on and at ISO 1600, through the Astro-Physics Traveler 105mm f/6 apo refractor with the Hutech field flattener.
I was sent an early sample of the EOS Ra, and earlier this autumn also had a sample of the stock EOS R.
Both were sent for testing so I could prepare a test report for Sky and Telescope magazine. The full test report will appear in an upcoming issue.
The large emission nebula IC 1396 in Cepheus with the orange “Garnet Star” at top, and the Elephant Trunk Nebula, van den Bergh 142, at bottom as a dark lane protruding into the emission nebula. This is a stack of 5 x 6-minute exposures with the Canon EOS Ra mirrorless camera at ISO 1600 through the Astro-Physics Traveler apo refractor at f/6 with the Hotech field flattener. Stacked, aligned and processed in Photoshop.
• How the Ra compares to previous “a” models and third-party filter-modified cameras
• How the Ra works for normal daylight photography
• Noise levels compared to other cameras
• Features unique to the EOS Ra, such as 30x Live View focusing
Messier 52 open cluster, at left, and the Bubble Nebula, NGC 7635 below and to the right of it, at centre, plus the small red nebula NGC 7538 at right. The open cluster at lower right is NGC 7510. All in Cassiopeia. This is a stack of 8 x 6-minute exposures at ISO 1600 with the Canon EOS Ra camera and Astro-Physics Traveler apo refractor at f/6 with the Hotech field flattener. No LENR dark frame subtraction employed as the temperature was -15° C.
UPDATE — November 25, 2019
As part of further testing I shot the Heart and Soul Nebulas in Cassiopeia through my little Borg 77mm f/4 astrograph with both the EOS Ra and my filter-modified 5D MkII (modified years ago by AstroHutech) to compare which pulled in more nebulosity. It looked like a draw.
Both images are single 8-minute exposures, taken minutes apart and developed identically in Adobe Camera Raw, but adjusted for colour balance to equally neutralize the sky background. The histograms look similar. Even so, the Ra looks a little redder overall. But keep in mind a sky or nebula can be made to appear any shade of red you like in processing.
The question is which camera shows more faint nebulosity?
The modified 5D MkII has always been my favourite camera for this type of astrophotography, picking up more nebulosity than other “a” models I’ve tested, including the Nikon D810a.
But in this case, I’d say the EOS Ra is performing as well as, if not better than the 5D MkII. How well any third-party modified camera you buy now performs will depend which, if any, filter the modifier installs in front of the sensor. So your mileage will vary.
For most of my other testing I shot through my much-prized Astro-Physics Traveler, a 105mm aperture f/6 apochromatic refractor on the Astro-Physics Mach1 mount.
To connect the EOS Ra (with its new RF lens mount) to my existing telescope-to-camera adapter and field flattener lens I used one of Canon’s EF-EOS R lens adapters.
The bottom line is that the EOS Ra works great!
It performs very well on H-alpha-rich nebulas and has very low noise. It will be well-suited to not only deep-sky photography but also to wide-field nightscape and time-lapse photography, perhaps as Canon’s best camera yet for those applications.
WHAT ABOUT THE PRICE?
The EOS Ra will sell for $2,500 US, a $700 premium over the cost of the stock EOS R. Some complain. Of course, if you don’t like it, you don’t have to buy it. This is not an upgrade being forced upon you.
As I look at it, it is all relative. When Nikon’s astronomy DSLR, the 36 Mp D810a, came out in 2015 it sold for $3,800 US, $1,300 more than the EOS Ra. It was, and remains a fine camera, if you can find one. It is discontinued.
A 36 Mp cooled and dedicated CMOS astro camera, the QHY367, with the same chip as the D810a, goes for $4,400, $1,900 more than the Ra. Yes, it will produce better images I’m sure than the EOS Ra, but deep-sky imaging is all it can do. At a cost, in dollars and ease of use.
And yes, buying a stock EOS R and having it modified by a third party costs less, and you’ll certainly get a good camera, for $300 to $400 less than an Ra. But …
• The EOS Ra has a factory adjusted white balance for ease of “normal” use — no need to buy correction filters. So there’s a $$ saving there, even if you can find clip-in correction filters for the EOS R — you can’t.
• And the Ra retains the sensor dust cleaning function. Camera modifier companies remove it or charge more to reinstall it.
• And the 30x live view magnification is very nice.
• The EOS Ra also carries a full factory warranty.
Do I wish the EOS Ra had some other key features? Sure. A mode to turn all menus red would be nice. As would an intervalometer built-in, one that works with the Bulb Timer to allow sequences of programmed multi-minute exposures. Both could be added in with a firmware update.
And providing a basic EF-EOS R lens adapter in the price would be a welcome plus, as one is essential to use the EOS Ra on a telescope.
That’s my take on it. I’ll be buying one. But then again I bought the 20Da, twice!, and the 60Da, and I hate to think what I paid for those much less capable cameras.
BONUS TEST — The RF 15-35mm L Lens
Canon is also releasing an impressive series of top-class RF lenses for their R mirrorless cameras. The image below is an example astrophoto with the new RF 15-35mm f/2.8 L zoom lens, an ideal combination of focal lengths and speed for nightscape shooting.
Orion and the winter stars rising on a late October night, with Sirius just clearing the horizon at centre bottom, Capella and the Pleiades are at top. M44 cluster is at far left. Taken with the Canon 15-35mm RF lens at 15mm and f/2.8 and the EOS Ra camera at ISO 800 as part of testing. A stack of 4 x 2-minute exposures on the Star Adventurer tracker.
Below is a further set of stacked and processed images with the RF 15-35mm L lens, taken in quick succession, at 15mm, 24mm, and 35mm focal lengths, all shot wide open at f/2.8. The EOS Ra was on the Star Adventurer tracker (as below) to follow the stars.
Click or tap on the images below to view a full-resolution version for closer inspection.
15mm — Northern autumn Milky Way with RF 15-35mm at f/2.8 and at 15mm focal length. Taken with the EOS Ra at ISO 800 for a stack of 4 x 2-minute exposures.
24mm — Northern autumn Milky Way with RF 15-35mm at f/2.8 and at 24mm focal length. Taken with the EOS Ra at ISO 800 for a stack of 2 x 2-minute exposures.
35mm — Northern autumn Milky Way with RF 15-35mm at f/2.8 and at 35mm focal length. Taken with the EOS Ra at ISO 800 for a stack of 2 x 2-minute exposures.
The RF 15-35mm lens performs extremely well at 15mm exhibiting very little off-axis aberrations at the corners.
Off-axis aberrations do increase at the longer focal lengths but are still very well controlled, and are much less than I’ve seen on my older zoom and prime lenses in this focal length range.
The RF 15-35mm is a great complement to the EOS Ra for wide-field Milky Way images.
I was impressed with the new EOS Ra. It performs superbly for astrophotography.
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.
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.
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.
In short — I found the Nikon Z6 superb for astrophotography.
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
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
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.
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
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.
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.
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
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.
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 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
The Orion Nebula with the Nikon Z6
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.
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
A blank long exposure with no LENR applied – click or tap to open the image full screen
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.
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
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
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
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
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
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
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.
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.
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 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
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
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.
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.
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.
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.
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.
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.
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.
My Menu
As most cameras do, the Z6 also has a “My Menu” page which you can also populate with favourite menu commands.
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.
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.
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
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, 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.
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.
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 …
Functions in Layers are still limited. For example, there is no stacking and averaging for noise smoothing. Affinity Photo has those.
Filters, though abundant for artistic special effect “looks,” are limited in basic but essential functions. There is no Median filter, for one.
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.
The lack of support for third-party plug-ins means ON1 cannot work with essential time-lapse programs such as Timelapse Workflow or LRTimelapse.
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:
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:
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.
As with the 2018 edition, you still cannot copy and paste masked local adjustments from image to image, limiting their use.
Exporting those images is slow.
Deep-Sky: ON1 is not a program I can recommend for deep-sky image processing:
Stars inevitably end up with unsightly sharpening haloes.
De-Bayering artifacts add blocky textures to the sky background.
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 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
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.
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.
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 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
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
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
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, 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.
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’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
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 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).
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
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
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 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 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.
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
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.
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
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.
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
A 400% close-up of the final Andromeda Galaxy image. It shows haloed stars and a textured and noisy sky background.
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.
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
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
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.
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
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.
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’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.
I put the new Sony a7III mirrorless camera through its paces for the features and functions we need to shoot the night sky.
Sony’s a7III camera has enjoyed rave reviews since its introduction earlier in 2018. Most tests focus on its superb auto exposure and auto focus capabilities that rival much more costly cameras, including Sony’s own a7rIII and a9.
For astrophotography, none of those auto functions are of any value. We shoot everything on manual. Indeed, the ease of manually focusing in Live View is a key function.
In my testing I compared the Sony a7III to two competitive DSLRs, the Canon 6D MkII and Nikon D750.
All three are “entry-level” full-frame cameras, with 24 to 26 megapixels and in a similar price league of $1,500 (Nikon) to 2,000 (Sony).
I tested a Sony a7III purchased locally. It was not supplied to me by Sony in return for an “influential” blog post.
I did this testing in preparation for the new third edition of my Nightscapes and Time-Lapse eBook, which includes information on Sony mirrorless cameras, as well as many, many other updates and additions!
NOTE:Click or Tap on most images to bring them up full-frame for inspection.
MILKY WAY AT DINOSAUR PARK A stack of 2 x 90-second exposures for the ground, to smooth noise, and at f/2.8 for better depth of field, plus a single 30-second untracked exposure at f/2 for the sky. All with the Laowa 15mm lens and Sony a7III at ISO 3200.
Mirrorless vs. DSLR
COMPACT CAMERA and LENS The Sony a7III with the compact but fast Laowa Venus Optics 15mm f/2 lens.
As with Sony’s other popular Alpha 7 and 9 series cameras, the new Alpha 7III is a full-frame mirrorless camera, a class of camera Canon and Nikon have yet to offer, though models are rumoured or promised.
In the meantime, Sony commands the full-frame mirrorless market.
As its name implies, a mirrorless camera lacks the reflex mirror of a digital single lens reflex camera that, in a DSLR, provides the light path for framing the scene though the optical viewfinder.
SONY LIVE VIEW The Sony a7III’s excellent Live View screen display. You can see the Milky Way!
In a mirrorless, the camera remains in “live view” all the time, with the sensor always feeding a live image to either or both the rear LCD screen and electronic viewfinder (EVF). While you can look through and frame using the EVF as you would with a DSLR, you are looking at an electronic image from the sensor, not an optical image from the lens.
The advantage of purely electronic viewing is that the image you are previewing matches the image you’ll capture, at least for short exposures. The disadvantage is that full-time live view draws more power, with mirrorless cameras notorious for being battery hungry.
Other mirrorless advantages include:
Compact size and lighter weight, yet offering all the image quality of a full-frame DSLR.
The thinner body allows the use of lenses from any manufacturer, albeit requiring the right adapter, an additional expense.
Lenses developed natively for mirrorless models can be smaller and lighter. An example is the Laowa 15mm f/2 I used for some of the testing.
The design lends itself to video shooting, with many mirrorless cameras offering 4K as standard, while often in DSLRs only high-end models do.
More rapid-fire burst modes and quieter shutters are a plus for action and wedding photographers, though they are of limited value for astrophotography.
Points of Comparison
CAMERA TRIO The Sony a7III, Nikon D750, and Canon 6D Mark II. Note the size difference.
In testing the Sony a7III I ignored all the auto functions. Instead, I concentrated on those points I felt of most concern to astrophotographers, such as:
Noise levels
Effectiveness of Long Exposure Noise Reduction (LENR)
Quality of Raw files, such as sharpness of stars
Brightness of Live View for framing and focusing
Uniformity of sensor illumination
Compatibility for time-lapse imaging
Battery life
TL;DR Conclusions
DEEP-SKY TEST The North America Nebula with the Sony a7III and a Meade 70mm f/5 astrographic refractor, for a single 4-minute exposure at ISO 1600. The reds have been boosted in processing.
Noise
Levels of luminance and chrominance noise were excellent and similar to – but surprisingly not better than – the Nikon D750.
Star Eater
The Star Eater is effectively gone. Stars are not smoothed out in long exposures.
ISO Invariance
The Sony exhibited good – though not great – “ISO invariant” performance.
Dark Frames
Dark frame subtraction using Long Exposure Noise Reduction removed most – but not all – hot pixels from thermal noise.
Live View Focusing and Framing
Live View was absolutely superb, though the outstanding Bright Monitoring function is as well-hidden as Sony could possibly make it.
Sensor Illumination Uniformity
The Sony showed some slight edge-of-frame shadowing from the mask in front of the sensor, as well as a weak purple amp glow.
Features
• The a7III lacks any internal intervalometer or ability to add one via an app. But it is compatible with many external intervalometers and controllers.
• The a7III’s red sensitivity for recording H-Alpha-emitting nebulas was poor.
• It lacks the “light-frame” buffer offered by full-frame Canons that allows shooting several frames in quick succession even with LENR turned on.
Video Capability
The a7III offers 4K video and, at 24 frames-per-second, is full-frame. Shutter speeds can be as slow as 1/4-second, allowing real-time aurora shooting at reasonable ISO speeds.
Battery Life
Shooting typical 400-frame time-lapses used about 40% of the battery capacity, similar to the other DSLRs.
Overall Recommendations
The Sony a7III is a superb camera for still and time-lapse nightscape shooting, and excellent for real-time aurora videos. It is good, though not great, for long-exposure deep-sky imaging.
STAR TRAILS and AURORA With the Laowa 15mm lens and Sony a7III, for 155 exposures, all 20 seconds at f/2.8 and at ISO 800, and taken as part of a 360-frame time-lapse.
Noise
The Sony a7III uses a sensor that is “Backside Illuminated,” a feature that promises to improve low-light performance and reduce noise.
I saw no great benefit from the BSI sensor. Noise at typical astrophoto ISO speeds – 800 to 6400 – were about equal to the four-year-old Nikon D750.
That was a bit surprising. I expected the new BSI-equipped Sony to better the Nikon by about a stop. It did not. This emphasizes just how good the Nikon D750 is.
Nevertheless, noise performance of the Sony a7III was still excellent, with both the Sony and Nikon handily outperforming the Canon 6D MkII, with its slightly smaller pixels, by about a stop in noise levels.
NOTE: I performed all Raw developing with Adobe Camera Raw v10.3. It is possible some of the artifacts I saw are due to ACR not handling the a7III’s .ARW files as well as it should. But to develop all the images from Sony, Nikon, and Canon equally for comparisons, ACR is the best choice.
COMPARING NOISE The Sony a7III exhibited noise levels similar to the Nikon D750 at high ISOs, with the Sony and Nikon each about a stop better for noise than the Canon 6D MkII.
NOISE AT ISO 3200 At ISO 3200, a common nightscape ISO speed, all three cameras performed well in this moonlit scene. The Canon shows a darker sky as its images were taken a few minutes later. The Nikon had the Sigma 14mm Art lens; the Canon and Sony used the same Rokinon 14mm SP lens.
NOISE AT ISO 6400 At ISO 6400, the Canon begins to show excessive noise, about a stop worse than the Nikon and Sony. No luminance noise reduction was applied to these images. All cameras show an equal number of stars recorded.
ISO Invariance
Both the Sony and Nikon use sensor and signal path designs that are “ISO invariant.” As a result, images shot underexposed at slower ISOs, then boosted in exposure later in processing look identical to properly exposed high-ISO images. Well, almost.
The Sony still showed some discoloration artifacts and added noise when boosting images by +4 EV that the Nikon did not. Even with uncompressed Raws, the Sony was not quite as ISO invariant as the Nikon, though the difference shows up only under extreme push-processing of badly underexposed frames.
Plus, the Sony was far better than the Canon 6D MkII’s “ISO variant” sensor. Canon really needs to improve their sensors to keep in the game.
ISO INVARIANCE COMPARISON Here I shot all three cameras at ISO 6400 for a correct exposure for the scene, and also at ISO 1600 and ISO 400, for images 2 and 4 stops underexposed respectively. These were then boosted in Adobe Camera Raw by 2 and 4 stops in Exposure Value (EV) to compensate. With ISO invariant sensors the boosted images should look similar to the well-exposed image.
ISO INVARIANCE CLOSE-UP A closeup of the scene shows the ISO variant Canon exhibited more noise and magenta discoloration in the +4 EV boosted image. The Nikon looks very clean, but the Sony also shows discoloration, green here, and an increase in noise. These are all uncompressed 14-bit Raw files.
SONY vs. NIKON Comparing just the two ISO-invariant cameras, the Sony and the Nikon, on another night, shows a similar performance difference when boosting underexposed slow-ISO images later in Camera Raw. The Sony begins to show more noise and now a magenta discoloration in the +3 and +4 EV images, similar to, but not as badly as does the ISO-variant Canon 6D MkII.
Compressed vs. Uncompressed
The Sony a7III offers a choice of shooting Uncompressed or Compressed Raw files. Uncompressed Raws are 47 Mb in size; Compressed Raws are 24 Mb.
In well-exposed images, I saw little difference in image quality.
But the dark shadows in underexposed nightscapes withstood shadow recovery better in the uncompressed files. Compressed files showed more noise and magenta discoloration in the shadows.
It is not clear if Sony’s compressed Raws are 12-bit vs. 14-bit for uncompressed files.
Nevertheless, for the demands of nightscape and deep-sky shooting and processing, I suggest shooting Uncompressed Raws. Use Compressed only if you plan to take lots of time-lapse frames and need to conserve memory card space on extended shoots.
UNCOMPRESSED vs. COMPRESSED Here I compare any image degradation from using compressed vs. uncompressed Raws, and from employing Long Exposure Noise Reduction. Images are only slightly underexposed and boosted by +1 EV in Camera Raw. Shadow noise is similar in all images, with the ones taken with LENR on showing elimination of colored hot pixels, as they should.
UNCOMPRESSED vs. COMPRESSED at -4EV The same scene but now underexposed by 4 stops and boosted by +4 EV later shows greater differences. The compressed image shows more noise and discoloration, and the images taken with LENR on, while eliminating hot pixels, show more random luminance noise. Keep in mind, these are vastly underexposed images.
UNCOMPRESSED vs. COMPRESSED DEEP-SKY A real-world deep-sky example shows the same comparison. All images are well-exposed, for tracked and guided 4-minute exposures. The ones taken with LENR on show fewer hot pixels. The compressed images appear identical to the uncompressed files for noise and star content.
Star Eater (Updated March 27, 2021)
Over the last year or so, firmware updates from Sony introduced a much-publicized penchant for Sony Alphas to “eat” stars even in Raw files, apparently due to an internal noise reduction or anti-aliasing routine users could not turn off. Stars were smoothed away along with the noise in exposures longer than 3.2 seconds in some Sony cameras (longer than 30 seconds in others).
I feel that in the a7III the Star Eater has been largely vanquished.
While others beg to differ and claim this camera still eats stars, they offer no evidence of it other than graphs and charts, not A-B photos of actual tracked starfields taken with the Sony vs. another camera thought not to eat stars.
As the images below show, there is a very slight one-pixel-level softening that kicks in at 4 seconds and longer but it did not eat or wipe out stars. Stars are visible to the same limiting magnitude and close double stars are just as well resolved across all exposures. Indeed, at slower ISOs and longer exposures, more stars are visible.
I saw none of the extreme effects reported by others with other Sonys, where masses of faint stars disappeared or turned into multi-colored blotches. It is possible the effect is still present in other Sony Alpha models. I have not tested those.
But in the a7III, I did not see any significant “star eating” in any long exposures even up to the 4 minutes I used for some deep-sky shots. In images taken at the same time with other cameras not accused of star eating, the Sony showed just as many faint stars as the competitors. Stars were visible to just as faint a limiting magnitude, and that’s what counts, NOT graphs and charts, especially when such results are not shown for other cameras.
In short, long exposures showed just as many stars as did short exposures.
This was true whether I was shooting compressed or uncompressed Raws, with or without Long Exposure Noise Reduction. Neither compression nor LENR invoked “star eating.”
STAR EATER SERIES at 200% This series of tracked images (shown here blown up 200%) goes from 2 seconds to 2 minutes, with decreasing ISO speed to equalize the exposure value across the series. Between 3.2s and 4s a very slight one-pixel-level softening does kick in, reducing noise and very slightly blurring stars. Yet, just as many stars are recorded and are resolved, and at the lower ISOs/longer exposures more stars are visible because faint stars are not lost in the noise.
STAR EATER SERIES at 400% This is the same series as above but now blown up 400% to better reveal the very subtle change in pixel-level sharpness as exposure lengthened from 3.2 to 4 seconds. Noise (most noticeable in the trees) is reduced and stars are very slightly softened. But none are “eaten” or wiped out. And star colors are not affected, though very small stars are sometimes green, an effect seen in other cameras due to de-Bayering artifacts.
STAR EATER DEEP-SKY #1 Tracked deep-sky images through a telescope using 4-minute exposures show the Sony a7III recording an equal number of faint stars as the Canon 6D MkII. No luminance noise reduction was applied to these images in processing.
STAR EATER DEEP-SKY #2 Another example with 4-minute exposures again demonstrates no problems recording faint stars. The Canon does show more noise than the Sony. No noise reduction was applied in processing.
SONY and NIKON COMPARED For yet more evidence, this is a comparison of the Sony a7III vs. the Nikon D750 in tracked 90-second exposures with 14mm lenses. Again, the Sony records just as many stars as the Nikon.
LENR Dark frames
For elimination of hot pixels from thermal noise I prefer to use Long Exposure Noise Reduction when possible for nightscape and deep-sky images, especially on warm summer nights.
Exceptions are images taken for star trail stacking and for time-lapses, images that must be taken in quick succession, with minimal time gap between frames.
Turning on LENR did eliminate most hot pixels in long exposures, but not all. A few remained. Also, when boosting the exposure a lot in processing, the images taken with LENR on showed more shot and read noise than non-LENR frames.
The dark frame the camera was taking and subtracting was actually adding some noise, perhaps due to a temperature difference. The cause is not clear.
Sony advises that when using LENR Raw images are recorded with only 12-bit depth, not 14-bit. This might be a contributing factor. Yet frames taken with LENR on were the same 47 Mb size as normal uncompressed frames.
For those who think this is normal for LENR use, the Nikon D750 shows nothing like this – frames taken with LENR on are free of all hot pixels and do not show more shot or read noise, nor deterioration of shadow detail from lower bit depths.
However, I emphasize that the noise increase from using LENR with the Sony was visible only when severely boosting underexposed images in processing.
In most shooting situations, I found using LENR provided the overriding positive benefit of reducing hot pixels. It just needs to be better, Sony!
SONY WITH AND WITHOUT LENR These are 4-minute exposures of dark frames (i.e. the lens cap on!) taken at room temperature with and without Long Exposure Noise Reduction. In the Sony, LENR did not eliminate all hot pixels nor the magenta amp glow at the left edge. LENR also added a background level of fine noise. These have had exposure and contrast increased to exaggerate the differences.
NIKON WITH AND WITHOUT LENR Dark frames taken with the Nikon D750 under the same circumstances and processed the same show none of the residual hot pixels and added background noise when LENR is employed. Nor is there any amp glow anywhere along the frame edges.
SONY REAL-WORLD LENR COMPARISON A real-world example with the Sony, with a properly exposed nightscape, shows that the ill effects of using LENR don’t show up under normal processing. You do get the benefit of reduced hot pixels in shadows, especially on a warm night like this was. This is a blow-up of the lower corner of the frame, as indicated.
Sensor Illumination
How evenly an image is illuminated is a common factor when testing lenses.
But astrophotography, which often requires extreme contrast boosts, reveals non-uniform illumination of the sensor itself, regardless of the optics, originating from hardware elements in front of the sensor casting shadows onto the sensor.
This is most noticeable – indeed usually only noticeable – when shooting deep-sky targets though telescopes.
With DSLRs it is the raised mirror which often casts a shadow, produced a dark vignetted band along the bottom of the frame. Its extent varies from camera model to model.
With a mirrorless camera the sensor is not set far back in a mirror box, as it is in a DSLR. As such, I would have expected a more uniformly illuminated sensor.
SENSOR CLOSE-UP showing intruding mask edges.
Instead, I saw a slight shadowing at the top and bottom edges but just at the corners. This is from a thin metal mask in front of the sensor. It intrudes into the light path ever so slightly. It shouldn’t.
This is an annoying flaw, though applying “flat fields” or ad hoc local adjustments should eliminate this. But that’s a nuisance to do, and should not be necessary with a mirrorless camera.
Worse is that long deep-sky exposures at high ISOs also exhibited a faint purple glow at the left edge, perhaps from heat from nearby electronics, a so-called “amp glow.” Or I’ve read where this is from an internal infrared source near the sensor.
Taking a dark frame with LENR did not eliminate this, and it should, demonstrating again that for whatever reason in the a7III LENR is not as effective as it should be.
I have not seen such “amp” glows in cameras (at least in the DSLRs I’ve used) for a number of years, so seeing it in the new Sony a7III was another surprise.
This would be much tougher to eliminate in deep-sky images where the extreme contrast boosts we typically apply to images of nebulas and galaxies will accentuate any odd glows.
UPDATE: March 27, 2021 — Subsequent firmware updates seem to have eliminated this amp glow. One supplier of filter-modified cameras, Spencer’s Camera, who had refused to modify Sonys because of this glow, now lists many Sony Alphas as suitable for modification. However, the sensor masks and “green stars” (described below) still make the Sony a7III less desirable for deep-sky imaging than other mirrorless cameras I’ve tested.
SONY FIELD ILLUMINATION #1 The full field of a deep-sky image taken through an f/5 70mm astrographic refractor shows the minor level of edge darkening at the corners from shadowing of the sensor in the Sony.
SONY FIELD ILLUMINATION #2 The full field of a deep-sky image taken through an f/6 105mm refractor shows the level of edge darkening at the edges from shadowing of the sensor in the Sony, and the purple “amplifier” glow at the left edge present in all very long exposures.
Red Sensitivity
When shooting deep-sky objects, particularly red nebulas, we like a camera to have a less aggressive infrared cutoff filter, to pick up as much of the deep red Hydrogen-Alpha emission line as possible.
The Sony showed poor deep-red sensitivity, though not unlike other cameras. It was a little worse than the stock Canon 6D MkII.
This isn’t a huge detriment, as anyone who really wants to go after deep nebulosity must use a “filter-modified” camera anyway.
Canon and Nikon both offered factory modified cameras at one time, notably the Canon 60Da and Nikon D810a. Sony doesn’t have an “a” model mirrorless.
To get the most out of the Sony for deep-sky imaging you would have to have it modified by a third-party, though the amp glow described above makes it a poor choice for modification.
RED SENSITIVITY COMPARED Three deep-sky exposures compare cameras for red sensitivity: a filter-modified Canon 5D MkII, a stock Canon 6D MkII, and the stock Sony a7III. As expected the filter-modified camera picks up much more red nebulosity. The Sony doesn’t do quite as well as the Canon 6D MkII.
Live View Focusing and Framing
Up to now my report on the Sony a7III hasn’t shown as glowing a performance as all the YouTube reviews would have you believe.
But Live Focus is where the a7III really stands out. I love it!
In Live View it is possible to make the image so bright you can actually see the Milky Way live on screen! Wow! This makes it so easy to frame nightscapes and deep-sky fields.
FINDING BRIGHT MONITORING The excellent Bright Monitoring function is accessible only off the Custom Key menu where it appears as a choice on the Display/Auto Review2 page (below) that can be assigned to a C button.
But this special “Bright Monitoring” mode is as well hidden as Sony could make it. Unless you actually read the full-length 642-page PDF manual (you have to download it), you won’t know about it. Bright Monitoring does not appear in any of the in-camera menus you can scroll through, so you won’t stumble across it.
Instead, you have to go to the Camera Settings 2 page, then select Still Image–Custom Key. In the menu options that appear you can now scroll to one called Bright Monitoring. Surprise! Assign it to one of the hardware Custom C buttons. I put it on C2, making it easy to call up when needed.
The other Live View function that works well, but also needs assigning to a C button is the Camera Settings 1 > Focus Magnifier. I put this on C1. It magnifies the Live View by 5.9x or 11.7x, allowing for precise manual focusing on a star.
Two other functions are useful for Live View:
Camera Settings 2 > Live View Display > Setting Effect ON. This allows the Live View image to reflect the camera settings in use, better simulating the actual exposure, even without Bright Monitoring on.
Camera Settings 1 > Peaking Setting. Turning this ON superimposes a shimmering effect on parts of an image judged in focus. This might be an aid, or an annoyance. Try it.
In all, the Sony provides superb, if well-hidden, Live View options that make accurately framing and focusing a nightscape or time-lapse scene a joy.
Great Features for Astrophotography
Here are some other Sony a7III features I found of value for astrophotography, and for operating the camera at night.
SONY TILTING SCREEN It tilts up and down but does not flip out as with the Canon 6D MkII’s. Still, this is a neck- and back-saving feature for astrophotography.
Tilting LCD Screen
Like the Nikon D750, the Sony’s screen tilts vertically up and down, great for use when on a telescope, or on any tripod when aimed up at the sky. As photographers age, this becomes a more essential feature!
Custom Buttons
The four C buttons can be programmed for oft-used functions, making them easy to access at night. Standard functions such as ISO and Drive Mode are easy to get at on the thumb wheel, unlike the Nikon D750 where I am forever hunting for the ISO or Focus Zoom buttons, or the Canon 6D MkII which successfully hides the Focus Zoom and Playback buttons at night.
My Menu
In new models, Sony now offers the option of a final “My Menu” page which you can populate with often-used functions from the other 35 pages of menu commands!
Adaptability to Many Lenses
Using the right lens adapter (I use one from Metabones), it is possible to use lenses with mounts made for Canon, Nikon, Sigma and others. Plus there are an increasing number of lenses from third parties offered with native Sony E-mounts. This is good news, as astrophotography requires fast, high-quality lenses, and the Sony allows more choices.
Lighter Weight / Smaller Size
The compact a7III body weighs a measured 750 grams, vs. 900 grams each for the Nikon D750 and Canon 6D MkII. The lower weight can be helpful for use on lightweight telescopes, on small motion control devices, and for simply keeping weight and bulk down when traveling.
Dual Card Slots
Not essential, but having two card slots is very helpful, for backup, for handling overflows from very long time-lapse shoots, or assigning them for stills vs. movies, or Raws vs. JPGs. Only Slot 1 will work with the fastest UHS II cards that are needed for recording the highest quality 4K video.
USB Power
It is possible to power the camera though the USB port (indeed that’s how you charge the battery, as no separate battery charger is supplied as standard, a deficiency). This might be useful for long shoots, though likely as not that same USB port will be needed for an intervalometer or motion control device. But if the Sony had a built-in intervalometer…!
Display Options
To reduce battery drain it is possible to turn off the EVF completely – I find I never use it at night – and to turn off the LCD display when shooting, though the latter is an option you have to activate to add to the Display button’s various modes.
The downside is that when shooting is underway you get no reassuring indication anything is happening, except for a brief LED flash when an image is written to a card.
Electronic Front Curtain Shutter
Most DSLRs do not offer this, but the Sony’s option of an electronic front curtain shutter and the additional Silent Shooting mode completely eliminates vibration, useful for some high-magnification shooting through telephotos and telescopes.
LUNAR CLOSE-UPS COMPARED This trio compares closeups of the Moon taken with and without electronic front curtain shutter. All were taken through a 130mm refractor telescope at f/12 using a Barlow lens. The image with e-shutter and in Silent Mode is a tad sharper, but that could be just as much from variations in seeing conditions as from the lower vibration from using the electronic shutter.
What’s Missing for Astrophotography
Intervalometer — NOW INCLUDED! UPDATE: In April 2019 Sony issued a v3 Firmware update for the a7III which added an internal intervalometer. I’ve used this new function and it works very well.
I had originally remarked that this useful function was missing. But no more! Thank you Sony!
While a built-in intervalometer is not essential, I find I often do use the Canon and Nikon in-camera intervalometers for simple shoots. So it is great to have one available on the Sony. However, like other brands’ internal intervalometers Sony’s is good only for exposures up to 30 seconds long.
Bulb Timer or Long Exposures
However, while the Sony has a Bulb setting there is no Bulb Timer as there is with the Canon. The Bulb Timer would allow setting long Bulb exposures of any length in the camera.
Instead, for any exposures over 30 seconds long (or time-lapses with >30-second-long frames) the Sony must be used with an external Intervalometer. I use a $50 Vello unit, and it works very well. It controls the Sony through the camera’s Multi USB port.
In-Camera Image Stacking
Also missing, and present on most new Canons, are Multiple Exposure modes for in-camera stacking of exposures in a Brighten mode (for star trails) or Averaging mode (for noise smoothing).
Yes, this can all be done later in processing, but having the camera do the stacking can often be convenient, and great for beginners, as long as they understand what those functions do, or even that they exist!
Time-Lapse Smoothing
When using its internal intervalometer, the Nikon D750 has an excellent Exposure Smoothing option. This does a fine job smoothing frame-to-frame flickering in time-lapses, something the Canon cannot do. Nor the Sony, as it has no intervalometer at all.
Light Frame Buffer in LENR
This feature is little known and utilized, and only Canon full-frame cameras offer it. Turn on LENR and it is possible to shoot three (with the 6D MkII) or four (with the 6D) Raw images in quick succession even with LENR turned on. The Canon 5D series also has this.
The dark frame kicks in and locks up the camera only after the series of “light frames” are taken. This is wonderful for taking a set of noise-reduced deep-sky images for later stacking. Nikons don’t have this, not even the D810a, and not Sonys.
Illuminated Buttons
The Sony’s buttons are not illuminated. While these might add glows to long exposure images, if they could be designed not to do that (i.e. they turn off during exposures), lit buttons would be very handy at night.
Limited Touch Screen Functions
An alternative would be an LCD screen that was touch sensitive. The Sony a7III’s screen is, but only to select an area for auto focus or zooming up an image in playback. The Canon 6D MkII has a fully functional touch screen which can be, quite literally, handy at night.
INTERVALOMETER For time-lapses, the Sony must be used with an external intervalometer like this Vello unit.
Video Capability
Here’s another area where the new Sony a7III really shines.
It offers 4K (or more precisely UltraHD) video recording for videos of 3840 x 2160 pixels. (True 4K is actually 4096 x 2160 pixels.)
With a fast enough UHS-II Class card it can record 4K video up to 30 frames per second and at a bit rate of either 60 or 100 Mbps.
At 24 fps videos are full-frame with no cropping. Hurray! You can take full advantage of wide-angle lenses, great for auroras. At 30 fps, 4K videos are cropped with a 1.2x crop factor.
In Movie Mode ISO speeds go up to ISO 102,400, but are pretty noisy, if unusable at such speeds.
But when shooting aurora videos I found, to my surprise, I could “drag” the shutter speeds as slow as 1/4-second, fully 4 stops better than the Nikon’s slowest shutter speed of 1/60 second in Full HD, and 3 stops better than the Canon’s slowest movie shutter of 1/30 second.
Coupled with a fast f/1.4 to f/2 lens, the slow shutter speed allows real-time aurora shooting at “only” ISO 6400 to 12,800, for quite acceptable levels of noise. I am very impressed!
Real-time video of auroras is not possible with anything like this quality with the Nikon (I’ve used it often), and absolutely not with the Canon. And neither are 4K.
Is the a7III as good for low-light video as the Sony a7s models, with their larger 8.5-micron pixels?
I would assume not, but not having an a7s (either Mark I or II) to test I can’t say for sure. But the a7III should do the job for bright auroras, the ones with rapid motion worth recording with video, plus offer 24 megapixels for high-quality stills of all sky subjects.
I think it’s a great camera for both astrophoto stills and video.
AURORA VIDEO FRAME This is a frame grab from a real-time 4K video of a “Steve” aurora.
An example is in a 4K video I shot on May 6, 2018 of an usual aurora known as “STEVE.”
Steve Aurora – May 6, 2018 (4K) from Alan Dyer on Vimeo.
For another example of using the Sony a7III for recording real-time video of the night sky see this video of the aurora shot from Norway in March 2019.
The Northern Lights At Sea from Alan Dyer on Vimeo.
Battery Life
I found the a7III would use up about about 40% of the battery capacity in a typical 400-frame time-lapse on mild spring nights, with 30-second exposures. This is with the EVF and rear LCD Display OFF, and the camera in Airplane mode to turn off wireless functions to further conserve battery power. I was using the wired Vello intervalometer.
This is excellent performance on par with the DSLRs I use. At last, we have a mirrorless camera that not only doesn’t eat stars, it also does not eat batteries!
One battery can get you through a night of shooting, though performance will inevitably decline in winter, as with all cameras.
MILKY WAY and PLANETS With the Sony a7III and Laowa 15mm lens at f/2 for a stack of 4 exposures for the ground to smooth noise and one exposure for the sky, all 30 seconds at ISO 3200.
Lens and Telescope Compatibility
As versatile as a mirrorless camera is for lens choice, making use of that versatility requires buying the right lens adapter(s). They can cost anywhere from $100 to $400. The lowest cost units just adapt the lens mechanically; the more costly units also transfer lens data and allow auto focusing with varying degrees of compatibility.
WITH METABONES CANON ADAPTER The MetaBones Canon EF-to-Sony E mount adapter transfers lens data and allows auto focus to function.
For use on telescopes, the simple adapters will be sufficient, and necessary as many telescope-to-camera adapters and field flatteners are optimized for the longer lens flange-to-sensor distance of a DSLR. Even if you could get a mirrorless camera to focus without a lens adapter to add the extra spacing, the image quality across the field might be compromised on many telescopes.
I used the Metabones Canon-to-Sony adapter when attaching the Sony to my telescopes using my existing Canon telescope adapters. Image quality was just fine.
ADAPTING TO A TELESCOPE The MetaBones adapter, as will other brands, adds the correct lens flange to sensor distance for telescope field flatteners to work best.
Time-Lapse Controller Compatibility
Due to limitations set by Sony, controlling one of their cameras with an external controller can be problematic.
Devices that trigger only the shutter should be fine. That includes simple intervalometers like the Vello, the Syrp Genie Mini panning unit, and the Dynamic Perception and Rhino sliders, to name devices I use. However, all will need the right camera control cable, available from suppliers like B&H.
And, as I found, the Sony might need to be placed into Continuous shooting mode to have the shutter fire with every trigger pulse from the motion controller. When used with the Genie Mini (below) the Sony fired at only every other pulse if it was in Single shot mode, an oddity of Sony’s firmware.
Some time-lapse controllers are able to connect to a camera through its USB port and then adjust the ISO and aperture as well, for ramped “holy grail” sunset-to-Milky Way sequences.
For example, the TimeLapse+ View (see http://www.timelapseplus.com) works great for automated holy grails, but the developer recommends that with most Sonys the minimum allowed interval between shots is longer (8 to 14 seconds) than with Canons and Nikons. See http://docs.view.tl/#camera-specific-notes
SONY WITH THE SYRP GENIE MINI The Sony A7III worked well with the Syrp Genie Mini motion controller with the right shutter cable but only when placed in Continuous mode.
Recommendations
In conclusion, here’s my summary recommendations for the three competitive cameras, rating them from Poor, to Fair, to Good, to Excellent.
SONY: I deducted marks from the Sony a7III for deep-sky imaging for its lack of a light frame buffer, poor red sensitivity, odd LENR performance, and purple amp glow not seen on the other cameras and that dark frames did not eliminate.
However, I did not consider “star eating” to be a negative factor, as the Sony showed just as many stars and as well-resolved as did the competitors, and what more could you ask for?
I rate the Sony excellent for nightscape imaging and for real-time aurora videos. I list it as just “good” for time-lapse work only because it will not be fully compatible with some motion controllers and rampers. So beware!
NIKON: I deducted points for real-time video of auroras – the D750 can do them but is pretty noisy with the high ISOs needed. Its red sensitivity is not bad, but its lack of a light frame buffer results a less productive imaging cycle when using LENR on deep-sky shooting.
I know … people shoot dark frames separately for subtracting later in processing. However, I’ve found these post-shoot darks rarely work well, as the dark frames are not at the same temperature as the light frames, and often add noise or dark holes.
CANON: The 6D MkII’s lack of an ISO invariant sensor rears its ugly head in underexposed shadows in dark-sky nightscapes. I like its image stacking options, which can help alleviate the noise and artifacts in still images, but aren’t practical for time-lapses. Thus my Good rating for nightscapes but Fair rating for time-lapses. (See my test at https://amazingsky.net/2017/08/09/testing-the-canon-6d-mark-ii-for-nightscapes/)
While the 6D MkII has HD video, it is incapable of any low-light video work.
And its light-frame buffer is great for minimizing shooting time for a series of deep-sky images with in-camera LENR dark frames, which I find are the best for minimizing thermal noise. Give me a Canon full-frame any day for prime-focus deep-sky shooting.
It’s just a pity the 6D MkII has only a 3-frame buffer when using LENR. Really Canon? The 2008-vintage 5D MkII had a 5-frame buffer! Your cameras are getting worse for astrophotography while Sony’s are getting better.
SONY a7III
NIKON D750
CANON 6D Mk II
Nightscapes
Excellent
Excellent
Good
Time-Lapse
Good
Excellent
Fair
Real-Time Video (Auroras)
Excellent
Fair
Poor
Wide-field Deep Sky
Good
Good
Excellent
Telescopic Deep Sky
Fair
Good
Excellent
I trust you’ll find the review of value. Thanks for reading!
ADDENDUM as of JUNE 6, 2018
Since publishing the first results a number of people commented with suggestions for further testing, to check claims that:
The Sony would perform better for noise under dark sky conditions, at high ISOs, rather than the moonlit scene above. OK, let’s try that.
The Sony would perform better in an ISO Invariancy “face-off” if its ISOs were kept above 640, to keep all the images within the Sony’s upper ISO range of its dual-gain sensor design, with two ranges (100 to 400, and 640 on up). Fair enough.
What little “star-eater” effect I saw might be mitigated by shooting on Continuous drive mode or by firing the shutter with an external timer. That’s worth a check, too.
For the additional tests, I shot all images within a 3-hour span on the night of June 5/6, using the Sony a7III, Nikon D750, and Canon 6D MkII, with the respective lenses: the Laowa 15mm lens at f/2, the Sigma 14mm Art at f/2, and the Rokinon 14mm SP at f/2.5.
The cameras were on a Star Adventurer Mini tracker to keep stars pinpoints, though the ground blurred in the longer exposures.
DARK SKY NOISE TEST
I show only the Sony and Nikon compared here, shot at the common range of ISOs used for nightscape shooting, 800 to 12800. All images are equally well exposed. The inset image at right in Photoshop shows the scene, the Milky Way above dark trees in my backyard!
To the eye, the Sony and Nikon look very similar for noise levels, just as in the moonlit scene. Both are very good – indeed, among the best performing cameras for high-ISO noise levels. But the Sony, being four years newer than the Nikon, is not better.
BUT … what the Sony did exhibit was better details in the shadows than the Nikon.
And this was with equal processing and no application of Shadow Recovery. This is where the Sony’s Backside Illuminated sensor with presumably higher quantum efficiency in gathering photons might be providing the advantage. With its good shadow details, you have to apply less shadow recovery in post-processing, which does keep noise down. So points to Sony here.
SONY vs NIKON HIGH ISO under DARK SKIES Noise levels appeared visually similar but the Sony showed more shadow details. Excellent!
I did put all the high ISO images through the classic noise reduction program Noise Ninja to measure total Luminance and Chrominance noise, and included the Canon 6D MkII’s images.
The resulting values and graph show the Sony actually measured worse for noise than the Nikon at each high ISO speed, 3200 to 12800, though with both performing much better than the Canon.
The higher noise of the Canon is visually obvious, but I’d say the Sony a7III and Nikon D750 are pretty equal visually for noise, despite the numbers.
COMPARING NOISE WITH NOISE NINJA
DARK SKY ISO INVARIANCY
Again, here I show only the Sony and Nikon, the two “ISO invariant” cameras. The correct exposure for the scene was 30 seconds at ISO 6400 and f/2. The images shown here were shot at lower ISOs to underexposure the dark scene by 2 to 4 stops or EV. Those underexposed images were then boosted later in processing (in Adobe Camera Raw) by the required Exposure Value to equalize the image brightness.
Contrary to expectations, the Sony did not show any great loss in image quality as it crossed the ISO 640 boundary into its lower ISO range. But the Nikon did show more image artifacts in the “odd-numbered” ISOs of 640 and 500. In this test, the Nikon did not perform as well as the Sony for ISO invariancy. Go figure!
Again, the differences are in images vastly underexposed. And both cameras performed much better than the ISO “variant” Canon in this test.
DARK SKY ISO INVARIANCY Here the Sony a7III performed well and better than the Nikon D750.
STAR EATER REVISITED
I shot images over a wide-range of exposures, from 2 seconds to 2 minutes, but show only the ones covering the 2-second to 4-second range, where the “star-eater” anti-aliasing or noise smoothing applied by Sony kicks in (above 3.2 seconds it seems).
I shot with the Sony a7III on Single shot drive mode, on Continuous Low drive mode (with the camera controlling the shutter speed in both cases), and a set with the Sony on Bulb and the shutter speed set by an external Vello intervalometer.
This is really pixel peeping at 400%. In Single drive mode, stars and noise soften ever so slightly at 4 seconds and higher. In Continuous mode, I think the effect is still there but maybe a little less. In shots on Bulb controlled by the External Timer, maybe the stars at 4 seconds are a little sharper still. But this is a tough call. To me, the star eater effect on the Sony a7III is a non-issue. It may be more serious on other Sony alphas.
STAR EATING vs DRIVE MODE This series shows star sharpness in images taken in Single and Continuous drive modes, and in Externally Timed exposures.
DE-BAYERING STAR ARTIFACTS
An issue that, to me, has a more serious effect on star quality is the propensity of the Sony, and to some extent the Nikon, to render tiny stars as brightly colored points, unrealistically so. In particular, many stars look green, from the dominance of green-filtered photosites on Bayer-array sensors.
Here I compare all three cameras for this effect in two-minute tracked exposures taken with Long Exposure Noise Reduction (i.e. in-camera dark frame subtraction) off and on.
The Sony shows a lot of green stars with or without LENR. The Nikon seems to discolor stars only when LENR is applied. Why would that be? The Canon is free of any such issue – stars are naturally colored whether LENR dark frames are applied or not.
This is all with Raws developed with Adobe Camera Raw.
When opening the same Raws in other programs (ON1 Photo RAW, Affinity Photo, DxO PhotoLab, and Raw Therapee) the results can be quite different, with stars often rendered with fringes of hot, colored pixels. Or rendered with little or no color at all. Raw Therapee offers a choice of de-Bayering, or “de-mosaic,” routines, and each produces different looking stars, and none look great! Certainly not as good as the Canon rendered with Camera Raw.
What’s going on here is a mystery – it’s a combination of the cameras’ unique Raw file formats, anti-alias filter in front of the sensor (or lack thereof in the Sony), and the de-Bayering routines of all the many Raw developers wrestling with the task of rendering stars that occupy only a few pixels. It’s unfair to blame just the hardware or the software.
But this test re-emphasized my thoughts that Canon DSLRs remain the best for long-exposure deep-sky imaging where you can give images as much exposure time as they need, while the ISO invariant Sony and Nikons exceed at nightscape shooting where exposures are often limited and plagued by dark shadows and noise.
COLORED STARS COMPARISON The Sony shows a propensity to render small stars in many vivid and unreal colors. The Nikon can do so after LENR is applied. The Canon is more neutral and natural.
My free Amazing Sky Calendar for 2017 is now available for download! Plan your astronomical year!
Once again, I have prepared a free 12-month Calendar listing loads of celestial events, Moon phases, highlighted space events, and with small charts to show what’s happening in the sky for the coming year. Plus a set of my favourite images from 2016.
Here are my top tips for shooting terrific still-image nightscapes … and time-lapse movies of the night sky.
1. Go for pixel size, not pixel count
When choosing a camera for night sky scenes, the most important characteristic is not number of megapixels. Just the opposite.
The best cameras are usually models with more modest megapixel counts. Each of their individual pixels is larger and so collects more photons in a given exposure time, yielding higher a signal-to-noise ratio – or lower noise, critical for night shooting.
Cameras with pixels (the “pixel pitch”) 6 to 8 microns across are best. Many high-megapixel cameras have tiny 4-micron pixels.
Large-pixel cameras are often the full-frame models, such as the Canon 5D MkIII and 6D, the Nikon D610, D750, and Df, and the Sony a7s and a7S II.
Many “cropped-frame” cameras are now 18- to 24-megapixel models with smaller, noise-prone pixels. They can certainly be used, but will require more care in exposing well at lower ISOs, and in processing to smooth out noise without blurring detail.
2. Learn to fly on manual
While DSLRs and Compact System Cameras have amazing automatic functions we use none of them at night.
Instead, we use the camera on Manual or Bulb, dialling in shutter speed, aperture and ISO speed manually. We also have to focus manually, using Live View mode to focus on a bright star or distant light.
Learn the tradeoffs involved: Increasing ISO sensitivity of the sensor keeps exposure times down but increases noise. Opening up the lens aperture to f/2 or f/1.4 also keeps exposures short but introduces image-blurring aberrations, especially at the frame corners.
To prevent stars from trailing due to the sky’s motion adhere to the “500 Rule:” the maximum exposure time is roughly 500 divided by the focal length of your lens.
3. Expose to the right
At night, always give the sensor plenty of signal.
Use whatever combination of shutter speed, aperture and ISO will provide a well-exposed image. The image “histogram,” the graph of number of pixels at each brightness level shown above, should never be slammed to the left.
It should be a well-distributed “mountain range” of pixels, extending well to the right. If the 500 Rule restricts your shutter speed, and your desire for sharp images across the frame demands you shoot at f/2.8 or even slower, then don’t be afraid to bump up the ISO speed to whatever it takes to produce a good histogram and a well-exposed image.
Noise will look far worse if you underexpose, then try to boost the image brightness later in processing. Expose to the right!
4. Shoot Raw!
Shoot Raw. Period.
When comparing Raw and compressed JPG versions of the same image, you can be fooled into thinking the JPGs look better (i.e. smoother) because of the noise reduction the camera has applied to the JPG that is beyond your control. However, that smoothing has also wiped out fine detail, like stars.
By shooting Raw you get to control whatever level of noise reduction and sharpening the image needs later in processing.
JPGs are also 8-bit images with a limited tonal range – or palette – in which to record the subtle gradations of brightness and colour present in our images.
Imported Raw files are 16-bit, with a much wider tonal scale and colour palette. That’s critical for all astrophotos when, even with a well-exposed image, many tonal values are down in the dark end of the range. Processing Raw images makes it possible to extract detail in the shadows and highlights.
Even when shooting a time-lapse sequence, shoot Raw.
5. Take dark frames (sometimes!)
LENR reduces noise.
It’s a topic of some debate, but in my experience it is always better to turn on the camera’s Long Exposure Noise Reduction (LENR) function when shooting individual nightscape images. Doing so forces the camera to take a “dark frame,” an exposure of equal length but with the shutter closed.
It records just the noise, which the camera then subtracts from the image. Yes, it takes twice as long to acquire an image, but the image is cleaner, with fewer noisy pixels.
This is especially true when shooting on hot summer nights (the warmer the sensor the higher the noise). That said, you cannot use LENR when shooting frames for star trail composites or time-lapse movies.
For those, the interval between images should be no more than 1 to 5 seconds. Using LENR would introduce unsightly gaps in the trails or jumps in the star motion in time-lapses.
As an alternative, it is possible to take separate dark frames at the end of the night by simply covering the lens and taking exposures of the same duration and at the same ISO as your “light frames.”
Some stacking software, such as StarStax and the Advanced Stacker Actions have places to put these dark frames, to subtract them from the stack later in processing.
6. Use fast lenses
A fast lens is your best accessory.
While the “kit zoom” lenses that come with many DSLRs are great for shooting bright twilight or Full Moon scenes, they will prove too slow for dark starlit scenes with the Milky Way.
In addition to exposing to the right and shooting Raw, the secret to great nightscapes is to shoot with fast lenses, usually “prime” lenses with fixed focal lengths. They are usually faster and have better image quality than zooms.
Your most-used lens for nightscape and time-lapse shooting is likely to be a 14mm to 24mm f/2 to f/2.8 lens.
Fortunately, because we don’t need (and indeed can’t use) autofocus we can live happily with low-cost manual lenses, such as the models made in Korea and sold under brands such as Rokinon, Samyang and Bower. They work very well.
7. Get to know the Moon & Milky Way
For many nightscape and time-lapse shoots, the Moon is your light source for illuminating the landscape.
When the Moon is absent, the Milky Way is often your main sky subject.
Knowing where the Moon will be in the sky at its various phases, and when it will rise (in its waning phases after Full Moon) or set (in its waxing phases before Full) helps you a plan a shoot, so you’ll know whether a landscape will be well lit.
Astronomy apps for desktop computers and mobile devices are essential planning aids. A good one specifically for photographers is The Photographer’s Ephemeris.
Knowing in what season and time of night the Milky Way will be visible is essential if you want to capture it. Don’t try for Milky Way shots in spring – it isn’t up!
8. Keep it simple to start
Don’t be seduced by the fancy gear.
Time-lapse imaging has blossomed into a field replete with incredible gear for moving a camera incrementally during a shoot, and for automating a shoot as day turns to night.
I explain how to use all the fancy gear in my ebook, linked to below, however … Great time-lapses, and certainly still-frame nightscapes, can be taken with no more than a DSLR camera with a good fast lens and mounted on a sturdy tripod. Invest in the lens and don’t scrimp on the tripod.
Another essential for shooting multi-frame star trails and time-lapses is a hardware intervalometer ($50 to $150).
9. Learn the intricacies of intervals
For time-lapses, an intervalometer is essential.
Mastering exposure and focus in still images is essential for great time-lapse movies because they are simply made of hundreds of well-exposed still frames.
But move to time-lapses and you have additional factors to consider: how many frames to shoot and how often to shoot them. A good rule of thumb is to shoot 200 to 300 frames per sequence, shot with an interval of no more than 1 to 5 seconds between exposures, at least for starry night sequences.
However, most intervalometers (the Canon TC-80N3 is an exception) define their “Interval” setting to mean the time from when the shutter opens to when it opens again. In that case, you set the Interval to be a value 1 to 5 seconds longer than the exposure time you are using. That’s also true of the intervalometer function Nikon builds into their internal camera firmware.
Test first!
10. Go to beautiful places
While the gear can be simple, great shots demand an investment in time.
By all means practice at home and at nearby sites that are quick to get to. Try out gear and techniques at Full Moon when exposures are short (the Full Moon is bright!) and you can see what you are doing.
But beautiful images of landscapes lit by moonlight or starlight require you to travel to beautiful locations.
When you are on site, take the time to frame the scene well, just as you would during the day. Darkness is no excuse for poor composition!
While shooting nightscapes and time-lapses can be done with a minimal investment in hardware and software, it does require an investment in time – time to travel and spend nights shooting at wonderful places under the stars.
Enjoy the night!
I cover all these topics, and much more, in detail in my ebook How to Photograph & Process Nightscapes and Time-Lapses. Click the link below to learn more.
I’ve been an avowed Canon DSLR user for a decade. I may be ready to switch!
[NOTE:This review dates from 2015. Tests done today with current models would certainly differ. Canon’s EOS R mirrorless series, for example, offer much better ISO Invariancy performance but lack the “dark frame buffer” advantage of Canon DSLRs. And indeed, I have used the Nikon D750 a lot since 2015. But I did not give up my Canons!]
Here, in a technical blog, I present my tests of two leading contenders for the best DSLR camera for nightscape and astronomical photography: the Canon 6D vs. the Nikon D750. Which is better?
To answer, I subjected both to side-by-side outdoor tests, using exposures you’ll actually use in the field for typical nightscapes and for deep-sky images.
Both cameras are stock, off-the-shelf models. They have not had their filters modified for astronomy use. Both are 20- to 24-megapixel, full-frame cameras, roughly competitive in price ($1,900 to $2,300).
For images shot through lenses, I used the Canon L-Series 24mm on the Canon 6D, and the Sigma 24mm Art lens on the Nikon D750.
The bottom line:Both are great cameras, with the Nikon D750 having the edge for nightscape work, and the Canon 6D the edge for deep-sky exposures.
The 24.3-megapixel Nikon D750 has 5.9-micron pixels, while the 20.2-megapixel Canon 6D has slightly larger 6.5-micron pixels which, in theory, should lead to lower noise for the Canon. How do they compare in practice?
The scene used to test for noise (here with the Nikon images) showing the development settings applied to both the Nikon and Canon sets. NO noise reduction (colour or lunminance) was applied to any of the images, but Exposure, Shadows, Contrast and Clarity were boosted, and Highlights reduced.
I shot a moonlit nightscape scene (above) at five ISO settings, from 800 to 12800, at increasingly shorter exposures to yield identically exposed frames. I processed each frame as shown above, with boosts to shadows, clarity, and contrast typical for nightscapes. However, I applied no noise reduction (either luminance or color) in processing. Nor did I take and apply dark frames.
The blowups of a small section of the frame (outlined in the box in the upper right of the Photoshop screen) show very similar levels of luminance noise. The Canon shows slightly more color noise, in particular more magenta pixels in the shadows at high ISOs. Its larger pixels didn’t provide the expected noise benefit.
TEST #2 — Resolution
Much has been written about the merits of Canon vs. Nikon re: the most rigorous of tests, resolving stars down at the pixel level.
I shot the images below of the Andromeda Galaxy the same night through a 92mm aperture apo refractor. They have had minimal but equal levels of processing applied. At this level of inspection the cameras look identical.
But what if we zoom in?
For many years Nikon DSLRs had a reputation for not being a suitable for stellar photography because of a built-in noise smoothing that affected even Raw files, eliminating tiny stars along with noise. Raw files weren’t raw. Owners worked around this by turning on Long Exposure Noise Reduction, then when LENR kicked in after an exposure, they would manually turn off the camera power.
This so-called “Mode 3” operation yielded a raw frame without the noise smoothing applied. Clearly, this clumsy workaround made it impossible to automate the acquisition of raw image sequences with Nikons.
Are Nikons still handicapped? In examining deep-sky images at the pixel-peeping level (below), I saw absolutely no difference in resolution or the ability to record tiny and faint stars. With its 4-megapixel advantage the Nikon should resolve finer details and smaller stars, but in practice I saw little difference.
Closeup of telescope view of Andromeda Galaxy with Canon 6D 4 minute exposure at ISO 800 No noise reduction applied in processing
Closeup of telescope view of Andromeda Galaxy with Nikon D750 4 minute exposure at ISO 800 No noise reduction applied in processing
On the other hand I saw no evidence for Nikon’s “star eater” reputation. I think it is time to lay this bugbear of Nikons to rest. The Nikon D750 proved to be just as sharp as the Canon 6D.
Note that in the closeups above, the red area marks a highlight (the galaxy core) that is overexposed and clipped. Nikon DSLRs also have a reputation for having sensors with a larger dynamic range than Canon, allowing better recording of highlights before clipping sets in.
However, in practice I saw very little difference in dynamic range between the two cameras. Both clipped at the same points and to the same degree.
TEST #3 — Mirror Box Shadowing
An issue little known outside of astrophotography is that a DSLR’s deeply-inset sensor can be shadowed by the upraised mirror and sides of the mirror box. Less light falls on the edges of the sensor.
The vignetting effect is noticeable only when we boost the contrast to the high degree demanded by deep-sky images, and when shooting through fast telescope systems.
Here I show the vignetting of the Canon and Nikon when shooting through my 92mm refractor at f/4.5.
The circular corner vignetting visible in the images below is from the field flattener/reducer I employed on the telescope. It can be compensated for by using Lens Correction in Adobe Camera Raw, or eliminated by taking flat fields.
Demonstrating the level of vignetting and mirror-box shadowing with the Canon 6D on a TMB 92mm apo refractor with a 0.85x field flattener/reducer lens
Demonstrating the level of vignetting and mirror-box shadowing with the Nikon D750 on a TMB 92mm apo refractor with a 0.85x field flattener/reducer lens
The dark edge at the bottom of the frame is from shadowing by the upraised mirror. It can be eliminated only by taking flat fields, or reduced by using masked brightness adjustments in processing.
Both cameras showed similar levels of vignetting, with the Canon perhaps having the slight edge.
TEST #4 — ISO Invariancy
So far the Nikon D750 and Canon 6D are coming up fairly equal in performance. But not here. This is where the Nikon outperforms the Canon by quite a wide margin.
Sony sensors (used in Sony cameras and also used by Nikon) have a reputation for being “ISO Invariant.”
What does that mean?
A typical Milky Way nightscape with the Nikon D750 and Sigma 24mm Art lens. With no Moon, shot at very high ISO of 6400 and wide aperture of f/1.4 to show image quality under these demanding shooting circumstances. Lens correction and basic development setttings applied.
A typical Milky Way nightscape with the Canon 6D and Canon 24mm L lens (original model). With no Moon, shot at very high ISO of 6400 and wide aperture of f/1.4 to show image quality under these demanding shooting circumstances. Lens correction and basic development setttings applied.
In the examples above, the correct exposure for the starlit scene was 15 seconds at f/1.4 at ISO 6400. See how the two cameras rendered the scene? Very similar, albeit with the Canon showing more noise and discoloration in the dark frame corners.
What if we shoot at the same 15 seconds at f/1.4 … but at ISO 3200, 1600, 800, and 400? These are now 1-, 2-, 3-, and 4-stops underexposed, respectively.
Then we boost the Exposure setting of the underexposed Raw files later in processing, by 1, 2, 3 or 4 f-stops. What do we see?
Nikon D750 – Comparing ISO Invariancy from ISO 6400 to 400 (Nightscape)
With the Nikon (above) we see images that look nearly identical for noise to what we got with the properly exposed ISO 6400 original. It really didn’t matter what ISO speed the image was shot at – we can turn it into any ISO we want later with little penalty.
Canon 6D – Comparing ISO Invariancy from ISO 6400 to 400 (Nightscape)
With the Canon (above) we get images with grossly worse noise in the shadows and with ugly magenta discoloration. Canons cannot be underexposed. You must use as high an ISO as needed for the correct exposure.
This “ISO Invariant” advantage of Nikon over Canon is especially noticeable in nightscapes scenes lit only by starlight, as above. The Canon turns ugly purple at -3EV underexposure, and loses all detail and contrast at -4EV underexposure.
For nightscape imaging this is an important consideration. We are limited in exposure time and aperture, and so are often working at the ragged edge of exposure. Dark areas of a scene are often underexposed and prone to noise. With the Nikon D750 these areas may still look noisy, but not much more so than they would be at that ISO speed.
With the Canon 6D, underexpose the shadows and you pay the price of increased noise and discoloration when you try to recover details in the shadows.
Apparently, the difference comes from where the manufacturer places the analog-to-digital circuitry: on the sensor (ISO invariant) or outboard on a separate circuit (ISO variant), and thus where in the signal path the amplification occurs when we boost ISO speed.
TEST #6 — Features
One could go on endlessly about features, but here I compare the two cameras on just a few key operating features very important to astrophotographers.
Intervalometer:
The Canon 6D has none, though newer Canons do. The Nikon D750, as do many Nikons, has a built-in intervalometer (shown above), even with a deflickering “Exposure Smoothing” option. However, exposure time is limited to the camera’s maximum of 30 seconds. Any longer requires an outboard intervalometer, as with the Canon.
If you use your camera with any motion control time-lapse unit, then it becomes the intervalometer, negating any capability built into the camera. But it’s nice to have.
Small Advantage: Nikon
Interval Length:
REVISED JUNE 2020:
When taking time-lapse or star trail images with the Canon I can set an interval as short as 1 second between frames, for a minimum of gaps or jumps in the stars. With the Nikon, controlled internally by its built-in intervalometer, a 1-second interval is possible but only if you set the interval to 33 seconds for a 30-second shutter speed.
That’s true of Canon and Sony built-in intervalometers as well, because on all cameras setting the exposure to 30 seconds really gives you a 32-second exposure. A little known fact! So the interval between shutter firings has to be set to 33 seconds. It’s tricky.
Advantage: None to either
Tiltable LCD Screen:
The Canon 6D has none. The Nikon D750 has a very useful tilt-out screen as shown above. This is hugely convenient for all forms of astrophotography. Only cropped-frame Canons have tilt-out screens. This feature might add weight, but it’s worth it!
Big Advantage: Nikon
Dark Frame Buffer:
The Nikon has none. With Long Exposure Noise Reduction ON, the Canon 6D allows up to four exposures to be shot in quick succession before the dark frame kicks in and locks up the camera. (Put the camera into Raw+JPG.)
[JUNE 2020: With the Canon 6D MkII the buffer allows three frames to be taken in quick succession.]
This is very useful for deep-sky imaging, for acquiring a set of images for stacking that have each had a dark frame subtracted in-camera, with a minimum of “down-time” at the camera.
Big Advantage: Canon
Live View Screen Brightness:
As pointed out to me by colleague Christoph Malin, with the Nikon you cannot dim the screen when in Live View mode and with Exposure Simulation ON. So it can be too bright at night. With the Canon you can dim the Live View screen — the LCD Brightness control affects the screen both during Live View as well as during playback of images.
Small Advantage: Canon
Software Compatibility:
Canon EOS cameras are well supported by advanced software, such as GBTimelapse (above) that controls only Canons, not Nikons, in complex time-lapse sequences, and Nebulosity, popular among deep-sky imagers for DSLR control.
Small Advantage: Canon
My take-away conclusions:
• Nikon DSLRs now are just as good for astrophotography as Canons, though that wasn’t always the case – early models did suffer from more noise and image artifacts than their Canon counterparts.
• Canon DSLRs, due to their sensor design, are more prone to exhibiting noise and image artifacts when images are greatly underexposed then boosted later in processing. Just don’t underexpose them – good advice for any camera.
It’s Perseid meteor shower time. Here are tips for seeing and shooting the meteors.
What are the Perseids?
They are an annual meteor shower, perhaps the most widely observed of the year, that peak every year about August 12. They are caused by Earth passing through a dust stream left by Comet Swift-Tuttle, last seen near Earth in 1992.
Each “shooting star” is really a bit of comet dust burning up in our atmosphere as it ploughs into us at 200,000 kilometres an hour. They don’t stand a chance of surviving – and none do.
All Perseid particles burn up. None reach Earth.
Perseid meteor caught night of August 12-13 2009 from Cypress Hills Prov Park in Saskatchewan at the annual Saskatchewan Summer Star Party. One frame of 250 shot as part of a time-lapse movie. Taken with Canon 5D MkII and 24mm lens at f/2.5 for 30s at ISO1600.
When are the Perseids?
The peak night of the Perseids this year is the night of Wednesday, August 12 into the early morning hours of August 13, with the peak hour occurring about midnight Mountain Daylight Time or 2 a.m. on the 13th for Eastern Daylight Time.
For North America, this is ideal timing for a good show this year. However, a good number of meteors will be visible the night before and night after peak night.
Even better, the Moon is near New and so won’t interfere with the viewing by lighting up the sky.
In all, except for the mid-week timing, conditions this year in 2015 couldn’t be better!
Perseid meteor caught night of August 12-13 2009 from Cypress Hills Prov Park in Saskatchewan at the annual Saskatchewan Summer Star Party. One frame of 260 shot as part of a time-lapse movie. Taken with Canon 20Da and 15mm lens at f/2.8 for 45s at ISO1600.
What do they look like?
Any meteor looks like a brief streak of light shooting across the sky. The brightest will outshine the brightest stars and are sure to evoke a “wow!” reaction.
However, the spectacular Perseids are the least frequent. From a dark site, expect to see about 40 to 80 meteors in an hour of patient and observant watching, but of those, only a handful – perhaps only 1 or 2 – will be “wow!” meteors.
A pair of Perseid meteors shoot at left in the late night sky at the Upper Bankhead parking lot in Banff National Park. The waning crescent Moon is just rising above the trees. Taken the night of Saturday, August 11 into the wee hours of Sunday, August 12, 2012 with the Canon 7D and 10-22mm Canon lens. This is a stack of two exposures, one for each meteor, each for 60 seconds at ISO 1250 and f/4.
Where do I look?
All the meteors will appear to radiate from a point in the constellation of Perseus in the northeastern sky in the early hours of the night, climbing to high overhead by dawn.
So you can face that direction if you wish, but Perseids can appear anywhere in the sky, with the longest meteor trails often opposite the radiant point, over in the southwest.
Shows unusual Perseid meteor varying in brightness? Or is this a satellite that mimics Perseid for position (it comes right out of the radiant point). Taken at Saskatchewan Star Party, August 14, 2010, using Canon 5D MkII and 15mm lens.
How do I look?
Simple – just lie back on a comfy lawn chair or patch of grass and look up!
But … you need to be at a dark location away from city lights to see the most meteors. You’ll see very little in a city or light-polluted suburbs.
Head to a site as far from city lights as you can, to wherever you’ll be safe and comfortable.
How do I take pictures?
To stand any chance of capturing these brief meteors you’ll need a good low-noise camera (a DSLR or Compact System Camera) with a fast (f/2.8 or faster) wide-angle lens (10mm to 24mm).
Sorry, keep your point-and-shoot camera and phone camera tucked away in your pocket – they won’t work.
Set up you camera on a tripod, open the lens to f/2.8 (wide open perhaps) and the ISO to 800 to 3200) and take a test exposure of 20 to 40 seconds. You want a well-exposed image but not over-exposed so the sky is washed out.
Set your exposure time accordingly – most cameras allow a maximum exposure of 30 seconds. Exposures longer than 30 seconds require a separate intervalometer to set the exposure, with the camera set on Bulb (B).
Take lots of pictures!
To up your chances of catching a meteor, you need to set the camera to shoot lots of frames in rapid succession.
Use an intervalometer to take shots one after the other with as little time between as possible – because that’s when a meteor will appear!
Barring an intervalometer, if you have standard switch remote control, set the camera on High Speed Continuous, and the shutter speed to 30 seconds, then lock the remote’s switch to ON to keep the camera firing. As soon as one exposure ends it’ll fire another.
Twin Perseids in this photo? Or are these satellites? Taken at SSSP, August 14, 2010, using Canon 5D MkII and 15mm lens.
What else do I need to know?
• Focus the lens carefully so the stars are sharp – the Live Focus mode helps for this. Focus on a bright star or distant light.
• Aim the camera to take in a wide swath of the sky but include a well-composed foreground for the most attractive shot.
• Aim northeast to capture meteors streaking away from the radiant. But you can aim the camera to any direction that lends itself to a good composition and still capture a meteor.
• To increase your chances, shoot with two or more cameras aimed to different areas of the sky. Meteors always appear where your camera isn’t aimed!
• Be patient! Despite shooting hundreds of frames only a handful will record a meteor, as only the brightest will show up.
Can I track the sky?
If you have a motorized equatorial mount or a dedicated sky tracking device (the iOptron Sky Tracker and Sky-Watcher Star Adventurer, each about $400, are popular), you can follow the stars while taking lots of shots. This avoids the stars trailing and allows you to use longer exposures.
The video above shows a Star Adventurer tracking the sky as it turns about its polar axis which is aimed up to a point near Polaris. Click the Enlarge and HD buttons to view the video properly.
Polar align the tracker, but then perhaps aim the camera to frame the summer Milky Way overhead. Take lots of 1- to 3-minute exposures, again at f/2.8 and ISO 800 to 1600. Some exposures will pick up meteors – with luck!
Tracking then stacking
Later, in processing, because the sky has remained fixed on the frame, it’s then possible to stack the images (using a “Lighten” blend mode on each image layer) so that the final composite frame contains more meteors, for an image with lots of meteors captured over an hour or more of shooting.
While it is possible to stack shots taken on a static tripod to produce such a meteor composite, doing so requires a lot of manual cutting, pasting and aligning of meteor images by hand. The result is a bit of a fake, though I’ve done it myself – the image at top is an example, though with only a trio of meteors.
On Wednesday, January 21 look low in the southwest for a conjunction of the Moon and inner planets.
Mercury is ending its brief evening appearance and proximity to Venus. But this week you can still spot it a binocular field or so below Venus as it descends back toward the Sun.
On Wednesday, January 21, look low in the southwest to sight the thin waxing crescent Moon sitting near Venus and Mercury, forming a wide triangle of inner rocky worlds.
The other rocky planet in the inner solar system, Mars, shines higher up in the evening twilight as a moderate brightness reddish star. The next night, January 22, the waxing Moon will sit beside Mars in a wide conjunction.
Catch the Moon-Mercury-Venus trio early, as they will set an hour or so after local sunset.
People gather at a rural observatory to gaze at the Milky Way on a summer night.
The clouds drifted through now and then but skies were mostly clear for the last of the Rothney Astrophysical Observatory‘s annual Milky Way Nights for 2014.
A tradition since 2009 and the Year of Astronomy, these dark-of-the-moon nights at the Observatory have proven hugely popular each summer despite the 10 p.m. start and 2 a.m. finish!
The main image at top shows a 360° panorama as people were gathering at the portable telescopes and lining up – in a blur – for a look inside the observatory domes.
Roland from the Royal Astronomical Society of Canada provided laser-guided star tours. How did we point out the stars and constellations before green lasers? In the hands of responsible astronomers they are a great tool for public education.
Here he’s pointing out Vega and the stars of the Summer Triangle. Look way up!
About 400 people attended on Saturday night, the last in a trio of nights this past week. As you can see, the event attracts people of all ages. It’s even a popular date night attraction.
At these summer stargazing sessions many people bring blankets to just lie back and look up, at a site away from the ugly glow of the city, here lighting up the clouds to the north.
The Amazing Sky 