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!
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.
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.
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.
The new smart AI programs should improve upon this. But do they?
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
COMPARING AI TO OLDER NON-AI PROGRAMS
The new generation of AI-based programs have garnered all the attention, leaving older stalwart noise reduction programs looking a little forlorn and forgotten.
Here I compare Camera Raw and two of the best of the AI programs, Topaz DeNoise AI and NoiseXTerminator, with two of the most respected of the “old-school” non-AI programs:
Dfine2, included with the Nik Collection of plug-ins sold by DxO (shown above), and
Reduce Noise v9 sold by Neat Image (shown below).
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.
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.
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.
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?
In the race for AI supremacy, one wonders where Adobe is in the field.
In the last couple of years Adobe has introduced several amazing and powerful “Neural Filters” into Photoshop, which work wonders with one click. And Lightroom and Camera Raw have received powerful AI-based selection and masking tools far ahead of most of the competition, with only Luminar Neo and ON1 Photo RAW coming close with similar auto-select capabilities.
But AI Noise Reduction? You think it would be a high priority.
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 to compete with the AI offerings of Topaz, ON1 and Luminar/Skylum.
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.
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.
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.
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.
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 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 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 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.
Canon RF15-35mm F/2.8 L IS USM
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
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
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.
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
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.
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
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.
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
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.
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.
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
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
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
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.
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.
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
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
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
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
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
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
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
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
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
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.
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.
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
Image Gallery withCanon RF70-200mm F/4 L IS USM
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!
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 a format similar to my other popular camera tests, I put the 45-megapixel Canon R5 mirrorless camera through its paces for the demands of astrophotography.
In a sequel to my popular post from September 2021 where I reviewed the Canon R6 mirrorless camera, here is a similar test of its higher-megapixel companion, the Canon R5. Where the R6 has a modest 20-megapixel sensor with relatively large 6.6-micron pixels, the R5 is (at present) Canon’s highest megapixel camera, with 45 megapixels. Each pixel is only 4.4 microns across, providing higher resolution but risking more noise.
Is the higher noise noticeable? If so, does that make the R5 less than ideal for astrophotography? To find out, I tested an R5 purchased locally in Calgary from The Camera Store in May 2022.
NOTE: CLICK orTAP on any image to bring it up full screen for closer inspection. The blog contains a lot of high-res images, so they may take a while to all load. Patience! Thanks!
The Canon R5 proved to be surprisingly low in noise, and has worked very well for nightscape, lunar and deep-sky photography (as shown below), where its high resolution does produce a noticeable improvement to image detail, with minimal penalty from higher noise. Its 8K video capability has a place in shooting the Moon, Sun and solar eclipses. It was not so well suited to shooting videos of auroras.
The Canon R5 is superb for its:
High resolution with relatively low noise
ISO invariant sensor performance for good shadow recovery
Good live view display with ISO boost in Movie mode
8K video has its attraction for eclipse photography
Good top LCD information screen missing in the R6
No magenta edge “amp glow” that the R6 shows
Higher 6x and 15x magnifications for precise manual focusing
Good battery life
Pro-grade Type N3 remote port
The Canon R5 is not so superb for its:
Noise in stills and movies is higher than in the R6
Propensity for thermal-noise hot pixels in shadows
Not so suitable for low-light video as the R6
Overheating in 8K video
Live View image is not as bright as in the R6’s Movie mode
CHOOSING THE R5
Since late 2019 my main camera for all astrophotography has been the Canon Ra, a limited-edition version of the original R, Canon’s first full-frame mirrorless camera that started the R series. The Ra had a special infra-red cutoff filter in front of the sensor that passed a higher level of visible deep-red light, making it more suitable for deep-sky astrophotography than a standard DSLR or DSLM (mirrorless) camera. The Ra was discontinued after two years on the market, a lifetime similar to Canon’s previous astronomical “a” models, the 20Da and 60Da.
I purchased the Canon R6 in late 2021, primarily to use it as a low-light video camera for aurora photography, replacing the Sony a7III I had used for several years and reviewed here. Over the last year, I sold all my non-Canon cameras, as well as the Canon 6D MkII DSLR (reviewed here), to consolidate my camera gear to just Canon mirrorless cameras and lenses.
The R6 has proven to be an able successor to the Sony for me, with the R6’s modest megapixel count and larger pixels making it excellent for low-light video. But the higher resolution of the R5 was still attractive. So I have now added it to my Canon stable. Since doing so, I have put it through several of my standard tests to see how suitable it is for the demands of astrophotography, both stills and video.
Here are my extensive results, broken down by various performance criteria. I hope you will find my review useful in helping you make a purchase decision.
LIVE VIEW FRAMING
First, why go mirrorless at all? For astrophotography, the big difference compared to even a high-end DSLR, is how much brighter the “Live View” image is when shooting at night. DSLM cameras are always in Live View – even the eye-level viewfinder presents a digital image supplied by the sensor.
And that image is brighter, often revealing more than what a DSLR’s optical viewfinder can show, a great advantage for framing nightscape scenes, and deep-sky fields at the telescope.
The R5 certainly presents a good live view image. However, it is not as bright nor as detailed as what the R6 can provide when placed in its Movie mode and with the ISO bumped up to the R6’s highest level of ISO 204,800, where the Milky Way shows up, live!
The R5 only goes as high as ISO 51,200, and so as I expected it does not provide as bright or detailed a preview at night as the R6 can. However, the R5 is better than the original R for live-view framing, and better than any Canon DSLR I’ve used.
LIVE VIEW FOCUSING
Like the R6, the R5 can autofocus accurately on bright stars and planets. By comparison, while the Ra can autofocus on distant bright lights, it fails on bright stars or planets.
Turning on Focus Peaking makes stars turn red, yellow or blue (your choice of colours) when they are in focus, as a reassuring confirmation.
In manual focus, an additional Focus Aid overlay, also found in the R6, provides arrows that close up and turn green when in focus on a bright star or planet.
Or, as shown above, you can zoom in by 6x or 15x to focus by eye the old way by examining the star image. These are magnification levels higher than the 5x and 10x of the R6 and most other Canon cameras, and are a great aid to precise focusing, necessary to make full use of the R5’s high resolution, and the sharpness of Canon’s RF lenses. The 15x still falls short of the Ra’s 30x for ultra-precise focusing on stars, but it’s a welcome improvement nonetheless.
In all, while the R5 is not as good as the R6 for framing in low light, it is better for precise manual focusing using its higher 15x magnification.
NOISE PERFORMANCE — NIGHTSCAPES
The key camera characteristic for astrophoto use is noise. There is no point in having lots of resolution if, at the high ISOs we use for most astrophotography, the detail is lost in noise. But I was pleasantly surprised that proved not to be the case with the R5.
As I show below, noise is well controlled, making the R5 usable for nightscapes at ISOs up to 3200, if not 6400 when needed in a pinch.
With 45 megapixels, at the upper end of what cameras offer today, the R5 has individual pixels, or more correctly “photosites,” that are each 4.4 microns in size, the “pixel pitch.”
This is still larger than the 3.7-micron pixels in a typical 24-megapixel cropped-frame camera like the Canon R10, or the 3.2-micron pixels found in a 32-megapixel cropped-frame camera like the Canon R7. Both are likely to be noisier than the R5, though will provide even higher resolution, as well as greater magnification with any given lens or telescope.
By comparison, the 30-megapixel full-frame R (and Ra) has a pixel pitch of 5.4 microns, while the 20-megapixel R6’s pixel pitch is a generous 6.6 microns. Only the 12-megapixel Sony a7SIII has larger 8.5-micron pixels, making it the low-light video champ.
The bigger the photosites (i.e. the larger the pixel pitch), the more photons each photosite can collect in a given amount of time – and the more photons they can collect, period, before they overfill and clip highlights. More photons equals more signal, and therefore a better signal-to-noise ratio, while the greater “full-well depth” yields higher dynamic range.
However, each generation of camera improves the signal-to-noise ratio by suppressing noise via its sensor design and improved signal processing hardware and firmware. The R5 and R6 each use Canon’s latest DIGIC X processor.
In nightscapes the R5 did show more noise at high ISOs, especially at ISO 6400, than the R6 and Ra, but the difference was not large, perhaps one stop at most, if that. What was noticeable was the presence in the R5 of more hot pixels from thermal noise, as described later.
At slower ISOs the R5 showed a similar level of noise as the R6 and Ra, but a finer-grained noise than the R6, in keeping with the R5’s smaller pixels. In this test set, the R5 did not exhibit noticeably more noise than the other two cameras. This was surprising.
NOTE: In these comparisons I have not resampled the R5 images down to the megapixel count of the R6 to equalize them, as that’s not what you would do if you bought an R5. Instead, I have magnified the R6 and Ra’s smaller images so we examine the same area of each camera’s images.
As with the R6, I also saw no “magic ISO” setting where the R5 performed better than at other settings. Noise increased in proportion to the ISO speed. The R5 proved perfectly usable up to ISO 3200, with ISO 6400 acceptable for stills when necessary. But I would not recommend the R5 for those who like to shoot Milky Way scenes at ISO 12,800.
For nightscapes, a good practice that would allow using lower ISO speeds would be to shoot the sky images with a star tracker, then take separate long untracked exposures for the ground.
NOTE: In my testing I look first and foremost at actual real-world results. For those interested in more technical tests and charts, I refer you to DxOMark’s report on the Canon R5.
NOISE PERFORMANCE — DEEP-SKY
Deep-sky imaging with a tracking mount is more demanding, due to its longer exposures of up to several minutes for each “sub-frame.”
On a series of deep-sky exposures through a telescope, above, the R5 again showed quite usable images up to ISO 1600 and 3200, with ISO 6400 a little too noisy in my opinion unless a lot of noise reduction was applied or many images were shot to stack later.
As with the nightscape set, at high ISOs, such as at ISO 6400, the R5 did show more noise than the R6 and Ra, as well as more colour splotchiness in the dark sky, and lower contrast. The lower dynamic range of the R5’s smaller pixels is evident here.
Just as with nightscapes, the lesson with the R5 is to keep the ISO low if at all possible. That means longer exposures with good auto-guiding, but that’s a best practice with any camera.
At lower ISOs that provide better dynamic range, shown above, the difference in noise levels between the three cameras was not that obvious. Each camera presented very similar images, with the R6 having a coarser noise than the Ra and R5.
In all, I was surprised the R5 performed as well as it did for deep-sky imaging. See my comments below about its resolution advantage.
The flaw in many Canon DSLRs, one documented in my 2017 review of the 6D Mark II, was their poor dynamic range due to the lack of an ISO invariant sensor design.
Canon R-series mirrorless cameras have largely addressed this weakness. As with the R and R6, the sensor in the R5 appears to be nicely ISO invariant.
Where ISO invariancy shows itself to advantage is on nightscapes where the starlit foreground is often dark and underexposed. Bringing out detail in the shadows in raw files requires a lot of Shadow Recovery or increasing the Exposure slider. Images from an ISO invariant sensor can withstand the brightening “in post” far better, with minimal noise increase or degradations such as a loss of contrast, added banding, or horrible discolourations.
As I do for such tests, I shot sets of images at the same shutter speed, one well-exposed at a high ISO, then several at successively lower ISOs to underexpose by 1 to 4 stops. I then brightened the underexposed images by increasing the Exposure in Camera Raw by the same 1 to 4 stops. In an ideal ISO invariant sensor, all the images should look the same.
The R5 performed well in images underexposed by up to 3 stops. Images underexposed by 4 stops started to fall apart with low contrast and a magenta cast. This was worse performance than the R6, which better withstood underexposure by as much as 4 stops, and fell apart at 5 stops of underexposure.
While it can withstand underexposure, the lesson with the R5 is to still expose nightscapes as well as possible, likely requiring a separate longer exposure for the dark ground. Expose to the right! Don’t depend on being able to save the image by brightening “in post.” But again, that’s a best practice with any camera.
Here I repeat some of the background information from my R6 review. But it bears repeating, as even skilled professional photographers often misunderstand the various forms of noise and how to mitigate them.
All cameras will exhibit thermal noise in long exposures, especially on warm nights. This form of heat-induced noise peppers the shadows with bright or “hot” pixels, often brightly coloured.
This is not the same as the shot and read noise that adds graininess to high-ISO images and that noise reduction software can smooth out later in post.
I found the R5 was prone to many hot pixels in long nightscape exposures where they show up in dark, underexposed shadows. I did not find a prevalence of hot pixels in well-exposed deep-sky images.
LONG EXPOSURE NOISE REDUCTION
With all cameras a setting called Long Exposure Noise Reduction (LENR) eliminates this thermal noise by taking a “dark frame” and subtracting it in-camera to yield a raw file largely free of hot pixels, and other artifacts such as edge glows.
The LENR option on the R5 did eliminate most hot pixels, though sometimes still left, or added, a few (or they might be cosmic ray hits). LENR is needed more on warm nights, and with longer exposures at higher ISOs. So the extent of thermal noise in any camera can vary a lot from shoot to shoot, and season to season.
The comparison above shows just thermal noise in long exposures with and without LENR, to show its effectiveness. However, bear in mind in this demo the raw files have been boosted a lot in exposure and contrast (using DxO PhotoLab with the settings shown) to exaggerate the visibility of the noise.
Like the R6, when LENR is actively taking a dark frame, the R5’s rear screen indicates “Busy,” which is annoyingly bright at night, exactly when you would be employing LENR. To hide this display, the only option is to close the screen. Instead, the unobtrusive top LCD screen alone should be used to indicate a dark frame is in progress. It does with the Ra, though Busy also displays on its rear screen as well, which is unnecessary.
As with all mirrorless cameras, the R5 lacks the “dark frame buffer” present in Canon full frame DSLRs that allows several exposures to be taken in quick succession even with LENR on.
With all Canon R cameras, turning on LENR forces the camera to take a dark frame after every light frame, doubling the time it takes to finish every exposure. That’s a price many photographers aren’t willing to pay, but on warm nights I find it can be essential, and a best practice, for the reward of cleaner images out of camera. I found it is certainly a good practice with the R5.
TIP: If you find hot pixels are becoming more obvious over time, try this trick: turn on the Clean Manually routine for 30 seconds to a minute. In some cameras this can remap the hot pixels so the camera can better eliminate them.
Using LENR with the R5 did not introduce any oddities such as oddly-coloured, green or wiped-out stars. Even without LENR I saw no evidence of green stars, a flaw that plagues some Sony cameras at all times, or Nikons when using LENR.
Canons have always been known for their good star colours, and the R5 maintains the tradition. According to DPReview the R5 has a mild low-pass anti-alias filter in front of its sensor. Cameras which lack such a sensor filter do produce sharper images, but stars that occupy only one or two pixels might not de-Bayer properly into the correct colours. I did not find that an issue with the R5.
As in the R6, I also saw no evidence of “star-eating,” a flaw Nikons and Sonys have been accused of over the years, due to aggressive in-camera noise reduction even on raw files. Canons have largely escaped charges of star-eating.
The R5 I bought was a stock “off-the-shelf” model. It is Canon’s now-discontinued EOS Ra that was “filter-modified” to record a greater level of the deep-red wavelength from red nebulas in the Milky Way. As I show below, compared to the Ra, the R5 did well, but could not record the depth of nebulosity the Ra can, to be expected for a stock camera.
However, bright nebulas will still be good targets for the R5. But if it’s faint nebulosity you are after, both in wide-field Milky Way images and telescopic close-ups, consider getting an R5 “spectrum modified” by a third-party supplier. Or modifying an EOS R.
EDGE ARTIFACTS and EDGE GLOWS
DSLRs are prone to vignetting along the top and bottom of the frame from shadowing by the upraised mirror and mirror box. Not having a mirror, and a sensor not deeply recessed in the body, largely eliminates this edge vignetting in mirrorless cameras.
While the Ra shows a very slight vignetting along the bottom of the frame (visible in the example above), the R5 was clean and fully illuminated to the edges, as it should be.
I was also pleased to see the R5 did not exhibit any annoying “amp glows” — dim, often magenta glows at the edge of the frame in long exposures, created by heat emitted from sensor electronics adding infrared (IR) glows to the image.
I saw noticeable amp glows in the Canon R6 which could only be eliminated by taking LENR dark frames. It’s a flaw that has yet to be eliminated with firmware updates. Taking LENR darks is not required with the R5, except to reduce thermal hot pixels as noted above.
With a lack of IR amp glows, the R5 should work well when filter-modified to record either more visible Hydrogen-alpha red light, or deeper into the infrared spectrum.
Resolution — Nightscapes
Now we come to the very reason to get an R5, its high resolution. Is the difference visible in typical astrophotos? In a word, yes. If you look closely.
If people only see your photos on Facebook or Instagram, no one will ever see any improvement in your images! But if your photos are seen as large prints, or you are simply a stickler for detail, then you will be happy with the R5’s 45 megapixels. (Indeed, you might wish to wait for the rumoured even higher megapixel Canon 5S!)
Nightscapes, and indeed all landscape photos by day or by night, is where you will see the benefit of more megapixels. Finer details in the foreground show up better. Images are less pixelated. In test images with all three cameras, the R5 did provide sharper images to be sure. But you do have to zoom in a lot to appreciate the improvement.
Resolution — lunar imaging
The Moon through a telescope is another good test of resolution. The above comparison shows how the R5’s smaller 4.4-micron pixels do provide much sharper details and less pixelation than the R6.
Of course, one could shoot at an even longer focal length to increase the “plate scale” with the R6. But at that same longer focal length the R5 will still provide better resolution, up to the point where its pixels are sampling more than what the atmospheric seeing conditions permit to be resolved. For lunar and planetary imaging, smaller pixels are always preferred, as they allow you to reach the seeing limit with shorter and often faster optical systems.
Resolution — deep sky
On starfields, the difference is not so marked. As I showed in my review of the R6, with “only” 20 megapixels the R6 can still provide detailed deep-sky images.
However, in comparing the three cameras above, with images taken at a focal length of 420mm, the R5 does provide sharper stars, with faint stars better recorded, and with less blockiness (i.e. “square stars”) on all the star images. At that focal length the plate scale with the R5 is 2.1 arc seconds per pixel. With the R6 it is 3.2 arc seconds per pixel.
The R5 is a good choice for shooting open and globular star clusters, or any small targets such as planetary nebulas, especially with shorter focal length telescopes. Bright targets will allow using lower ISOs, mitigating any of the R5’s extra noise.
With an 800mm focal length telescope, the plate scale with the R5 will be 1.1 arc seconds per pixel, about the limit most seeing conditions will permit resolving. With even longer focal length telescopes, the R5’s small pixels would be oversampling the image, with little gain in resolution, at least for deep-sky subjects. Lunar and planetary imaging can benefit from plate scales of 0.5 arc seconds per pixel or smaller.
CAN YOU CreatE resolution?
Now, one can argue that today’s AI-driven scaling programs such as ON1 Resize AI and Topaz Gigapixel AI can do a remarkable job up-sizing images while enhancing and sharpening details. Why buy a higher-megapixel camera when you can just sharpen images from a lower-resolution model?
While these AI programs can work wonders on regular images, I’ve found their machine-learning seems to know little about stars, and can often create unwanted artifacts.
In scaling up an R6 image by 200%, ON1 Resize AI 2022 made a mess of the stars and sky background. Topaz Gigapixel AI did a much better job, leaving few artifacts. But using it to double the R6 image in pixel count still produced an image that does not look as sharp as an original R5 image, despite the latter having fewer pixels than the upsized R6 image.
Yes, we are definitely pixel-peeping! But I think this shows that it is better to have the pixels to begin with in the camera, and to not depend on software to generate sharpness and detail.
The R5’s 45-megapixel sensor also makes possible its headline selling point when it was released in 2020: 8K movie recording, with movies sized 8192 x 4320 (DCI standard) or 7680 x 4320 (UHD standard) at 29.97 frames per second, almost IMAX quality.
Where the R6’s major selling point for me was its low-light video capability, the R5’s 8K video prowess was less important. Or so I thought. With testing, I can see it will have its place in astrophotography, especially solar eclipses.
Unlike the original Canon R and Rp, the R5 and R6 can shoot 4K movies sampled from the full width of their sensors, so there is no crop factor in the field of view recorded with any lens.
However, like the R6, the R5 also offers the option of a Movie Crop mode which samples a 4K movie from the central 4096 (4K-D) or 3840 (4K-U) pixels of the sensor. As I show above, this provides a “zoomed-in” image with no loss of resolution, useful when wide field of view is not so important as is zooming into small targets, such as for lunar and solar movies.
So what format produces the best resolution when shooting movies? As I show above, magnified frame grabs of the Moon demonstrate that shooting at 8K provides a much less pixelated and sharper result than either the 4K-Fine HQ (which creates a “High-Quality” 4K movie downsampled from 8K) or a standard 4K movie.
Shooting a 4K movie with the R6 also produced a similar result to the 4K movies from the R5. The slightly softer image in the R5’s 4K frame can, I think, be attributed more to atmospheric seeing.
Solar eclipse use
Shooting the highest resolution movies of the Moon will be of prime interest to astrophotographers when the Moon happens to be passing in front of the Sun!
That will happen along a narrow path that crosses North America on April 8, 2024. Capturing the rare total eclipse of the Sun in 8K video will be a goal of many. At the last total solar eclipse in North America, on August 21, 2017, I was able to shoot it in 4K by using a then state-of-the-art top-end Canon DSLR loaned to me by an IMAX movie production company!
And who knows, by 2024 we might have 100-megapixel cameras capable of shooting and recording the firehose of data from 12K video! But for now, even 8K can be a challenge.
However, do you need to shoot 8K to get sharp Moon, Sun or eclipse movies? The above shows the 8K frame-grab compared to the R5’s best quality full-frame 4K Fine, and the R5’s and R6’s 4K Movie Crop mode that doesn’t resample or bin pixels from the larger sensor to create a 4K movie. The Cropped movies look only slightly softer than the R5 at 8K, with less pixelation than the 4K Fine HQ movie.
When shooting the Sun or Moon through a telescope or long telephoto lens, the wide field of a full-frame movie might not be required, even to take in the two- or three-degree-wide solar corona around the eclipsed Sun.
However, if a wide field for the maximum extent of the outer corona, combined with sharp resolution is the goal, then a camera like the Canon R5 capable of shooting 8K movies will be the ticket.
And 8K will be ideal for wide-angle movies of the passage of the Moon’s shadow during any eclipse, or for moderate fields showing the eclipsed Sun flanked by Jupiter and Venus on April 8, 2024.
Like the R6, the R5 offers the option of shooting movies in Canon’s C-Log3 profile, which records internally in 10-bit, preserving more dynamic range in movies, up to 12 stops. The resulting movie looks flat, but when “colour graded” later in post, the movie records much more dynamic range, as I show above. Without C-Log3, the bright sunlit lunar crescent is blown out, as will be the Sun’s inner corona.
The bright crescent Moon with dim Earthshine is a good practice-run stand-in for the eclipsed Sun with its wide range of brightness from the inner to the outer corona.
Sample Moon Movies
For the full comparison of the R5 and R6 in my test shoot of the crescent Moon, see this narrated demo movie on Vimeo for the 4K movies, shot in various modes, both full-frame and cropped, with C-Log3 on and off.
Keep in mind that video compression in the on-line version may make it hard to see the resolution difference between shooting modes.
A “private link” 10-minute video on Vimeo demonstrating 4K video clips with the R5 and R6.
For a movie of the 8K footage, though downsized to 4K for the Vimeo version (the full sized 8K file was 29 Gigs!), see this sample movie below on Vimeo.
A “private link” video on Vimeo demonstrating 8K video clips with the R5.
Like the R6, the R5 can shoot at a dragged shutter speed as slow as 1/8-second. That slow shutter, combined with a fast f/1.4 to f/2 lens, and ISOs as high as 51,200 are the keys to shooting movies of the night sky.
Especially auroras. Only when auroras get shadow-casting bright can we shoot at the normal 1/30-second shutter speed of movies and at lower ISOs.
I was able to shoot a decent aurora one night from home with both the R5 and R6, and with the same fast TTArtisan 21mm f/1.5 RF lens. The sky and aurora changed in brightness from the time I shot with the R6 first to the R5 later. But even so, the movies serve as a look at how the two cameras perform for real-time aurora movies.
Auroras are where we need to shoot full-frame, for the maximum field of view, and at high ISOs. The R5’s maximum ISO is 51,200, while the R6 goes up to 204,800, though it is largely unusable at that speed for actual shooting, just for previewing scenes.
As expected, the R6 was much less noisy than the R5, by about two stops. The R5 is barely usable at ISO 51,200, while the R6 works respectably well at that speed. If auroras get very bright, then slower ISOs can be used, making the R5 a possible camera for low-light use, but it would not be a first choice, unless 8K auroras are a must-have.
Sample aurora Movies
For a narrated movie comparing the R5 and R6 at 4K on the aurora, stepping both through a range of ISO speeds, see this movie at Vimeo.
A “private link” video on Vimeo demonstrating 4K aurora clips with the R5 and R6.
For a movie showing the same aurora shot with the R5 at 8K, see this movie. However, it has been down-sized to 4K for on-line viewing, so you’ll see little difference between it and the 4K footage. Shooting at 8K did not improve or smooth noise performance.
A “private link” video on Vimeo demonstrating 8K aurora clips with the R5.
BATTERY LIFE — Stills and video
Canon’s new LP-E6NH battery supports charging through the USB-C port and has a higher 2130mAh capacity than the 1800mAh LP-E6 batteries. However, the R5 is compatible with the older batteries.
On mild nights, I found the R5 ran fine on one battery for the 3 to 4 hours needed to shoot a time-lapse sequence, or set of deep-sky images, with power to spare. Now, that was with the camera in “Airplane Mode,” which I always use regardless, to turn off the power-consuming WiFi and Bluetooth, which I never use on cameras.
As I noted with the R6, for demanding applications, especially in winter, the R5 can be powered by an outboard USB power bank that has Power Delivery or “PD” capability.
The exception for battery use is when shooting videos, especially 8K. That can drain a battery after an hour of recording, though it takes only 10 to 12 minutes of 8K footage to fill a 128 gigabyte card. While less than half that length will be needed to capture any upcoming total eclipse from diamond ring to diamond ring, the result is still a massive file.
More critically, the R5 is also infamous for overheating and shutting down when shooting 8K movies, after a time that depends on how hot the environment is. I found the R5 shot 8K or 4K Fine HQ for about 22 minutes at room temperature before the overheat warning first came on, then shut off recording two or three minutes later. Movie recording cannot continue until the R5 cools off sufficiently, which takes at least 10 to 15 minutes.
That deficiency might befoul unwary eclipse photographers in 2024. The answer for “no-worry” 8K video recording is the Canon R5C, the video-centric version of the R5, with a built-in cooling fan.
Features and usability
While certainly not designed with astrophotography in mind, the R5 has several hardware and firmware features that are astrophoto friendly.
Like all Canon cameras made in the last few years, the R5 has Canon’s standard articulated screen, which can be angled up for convenient viewing when on a telescope. It is also a full touch screen, with all important camera settings and menus adjustable on screen, good for use at night.
With 2.1 million dots, the R5’s rear screen has a higher resolution than the 1.62-million-dot screen of the R6, and much higher than the 1 million pixels of the Rp’s screen, but is the same resolution as in the R and Ra.
The R5, like the original R, has a top backlit LCD screen for display of current camera settings, battery level and Bulb timer. The lack of a top screen was one of my criticisms of the R6.
Yes, the hardware Mode dial of the R6 and Rp does make it easier to switch shooting modes, such as quickly changing from Stills to Movie. However, for astrophotography the top screen provides useful information during long exposures, and is handy to check when the camera is on a telescope or tripod aimed up to the sky, without spoiling dark adaptation. I prefer to have one.
The R5’s remote shutter port, used for connecting external intervalometers or time-lapse motion controllers, is Canon’s professional-grade three-pronged N3 connector. It’s sturdier than the 2.5mm mini-phono plug used by the Rp, R and R6. It’s a plus for the R5.
As with all new cameras, the R5’s USB port is a USB-C type. A USB-C cable is included.
Like the R6, the R5 has a dedicated magnification button on the back panel for zooming in when manually focusing or inspecting images. In the R and Ra, that button is only on the touch panel rear screen, where it has to be called up by paging to that screen, an inconvenience. While virtual buttons on a screen are easier to see and operate at night than physical buttons, I find a real Zoom button handy as it’s always there.
To handle the high data rates of 8K video and also 4K video when set to the high frame rate option of 120 fps, one of the R5’s memory card slots requires a CFexpress Type B card, a very fast but more costly format.
As I had no card reader for this format, I had to download movies via a USB cable directly from the camera to my computer, using Canon’s EOS Utility software, as Adobe Downloader out of Adobe Bridge refused to do the job. Plan to buy a card reader.
In the menus, you can choose to record video only to the CFexpress, and stills only to the SD card, or both stills and movies to each card for a backup, with the limitation that 8K and 4K 120fps won’t record to the SD card, even very fast ones.
Unlike the Canon R and Ra (which both annoyingly lack a built-in intervalometer), but like the R6, the R5 has an Interval Timer in its firmware. This can be used to set up a time-lapse sequence, but with exposures only up to the maximum of 30 seconds allowed by the camera’s shutter speed settings, true of most in-camera intervalometers. Even so, this is a useful function for simple time-lapses.
As with most recent Canon DSLRs and DSLMs, the R5 also includes a built-in Bulb Timer. This allows setting an exposure of any length (many minutes or hours) when the camera is in Bulb mode. However, it cannot be combined with the Interval Timer for multiple exposures; it is good only for single shots. Nevertheless, I find it useful for shooting long exposures for the ground component of nightscape scenes.
While Canon cameras don’t have Custom Function buttons per se (unlike Sonys), the R5’s various buttons and dials can be custom programmed to functions other than their default assignments. I assign the * button to turning on and off the Focus Peaking display and, as shown, the AF Point button to a feature only available as a custom function, one that temporarily brightens the rear screen to full, good for quickly checking framing at night.
A handy feature of the R5 is the ability to add an audio notation to images. You shoot the image, play it back, then use the Rate button (if so assigned) to record a voice memo of up to 30 seconds, handy for making notes in the field about an image or a shoot. The audio notes are saved as WAV files with the same file number as the image.
Like other EOS R cameras, the R5 has this notorious “feature” that trips up every new user who attaches their Canon camera to a telescope or manual lens, only to find the shutter suddenly doesn’t work. The answer is to turn ON “Release Shutter w/o Lens” found buried under Custom Functions Menu 4. Problem solved!
I provide more details of other features and settings of the R5, many of which are common to the R6, in my review of the R6 here.
No question, the Canon R5 is costly. Most buyers would need to have very good daytime uses to justify its purchase, with astrophotography a secondary purpose.
That said, other than low-light night sky videos, the R5 does work very well for all forms of astrophotography, providing a level of resolution that lesser cameras simply cannot.
Nevertheless, if it is just deep-sky imaging that is of interest, then you might be better served with a dedicated cooled-sensor CMOS camera, such as one of the popular ZWO models, and the various accessories that need to accompany such a camera.
But for me, when it came time to buy another premium camera, I still preferred to have a model that could be used easily, without computers, for many types of astro-images, particularly nightscapes, tracked wide-angle starfields, as well as telescopic images.
Since buying the R5, after first suspecting it would prove too noisy to be practical, it has in fact become my most used camera, at least for all images where the enhanced red sensitivity of the EOS Ra is not required. But for low-light night videos, the R6 is the winner.
However, to make use of the R5’s resolution, you do have to match it with sharp, high-quality lenses and telescope optics, and have the computing power to handle its large files, especially when stitching or stacking lots of them. The R5 can be just the start of a costly spending spree!
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.
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.
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
The Canon R6 is not so superb for its:
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
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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!
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.
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.
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.
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.
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.
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.
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.
However, the compression is not lossless. In high-ISO test images purposely underexposed, then brightened in post, I could see a slight degradation in cRAW images – the noise background looked less uniform and exhibited a blocky look, like JPG artifacts.
TIP: With two SD card slots in the R6 (the second card can be set to record either a backup of images on card one, or serve as an overflow card) and the economy of large SD cards, there’s not the need to conserve card space as there once was. I would suggest always shooting in the full RAW format. Why accept any compression and loss of image quality?
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.
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.
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 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.
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!).
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.
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.
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.
The R6, like the low-end Rp, lacks a top LCD screen for display of camera settings and battery level. In its place we get a traditional Mode dial, which some daytime photographers will prefer. But for astrophotography, a backlit top LCD screen provides useful information during long exposures.
Without it, the R6 provides no indication of battery level while a shoot is in progress, for example, during a time-lapse. A top screen is also useful for checking ISO and other settings by looking down at the camera, as is usually the case when it’s on a tripod or telescope.
The lack of a top screen is an inconvenience for astrophotography. We are forced to rely on looking at the brighter rear screen for all information. It is a flip-out screen, so can be angled up for convenient viewing on a telescope.
The R6 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.
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.
Unlike the Canon R and Ra (which still mysteriously lack a built-in interval timer, despite firmware updates), the R6 has one in its firmware. Hurray! This can be used to set up a time-lapse sequence, but on exposures only up to the maximum of 30 seconds allowed by the camera’s shutter speed settings, true of most in-camera intervalometers.
For 30-second exposures taken in succession as quickly as possible the interval on the R6 has to be set to 34 seconds. The reason is that the 30-second exposure is actually 32 seconds, true of all cameras. With the R6, having a minimum gap in time between shots requires an Interval not of 33 seconds as with some cameras, but 34 seconds. Until you realize this, setting the intervalometer correctly can be confusing.
Like all Canon cameras, the R6 can be set to take only up to 99 frames, not 999. That seems a dumb deficiency. Almost all time-lapse sequences require at least 200 to 300 frames. What could it possibly take in the firmware to add an extra digit to the menu box? It’s there at in the Time-lapse Movie function that assembles a movie in camera, but not here where the camera shoots and saves individual frames. It’s another example where you just can’t fathom Canon’s software decisions.
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.
As with most recent Canon DSLRs and DSLMs, the menu also includes a Bulb Timer. This allows setting an exposure of any length (many minutes or hours) when the camera is in Bulb mode. This is handy for single long shots at night.
However, it cannot be used in conjunction with the Interval Timer to program a series of multi-minute exposures, a pity. Instead, a separate outboard intervalometer has to be used for taking an automatic set of any exposures longer than 30 seconds, true of all Canons.
In Bulb and Bulb Timer mode, the R6’s rear screen lights up with a bright Timer readout. While the information is useful, the display is too bright at night and cannot be dimmed, nor turned red for night use, exactly when you are likely to use Bulb. The power-saving Eco mode has no effect on this display, precisely when you would want it to dim or turn off displays to prolong battery life, another odd deficiency in Canon’s firmware.
The Timer display can only be turned off by closing the flip-out screen, but now the viewfinder activates with the same display. Either way, a display is on draining power during long exposures. And the Timer readout lacks any indication of battery level, a vital piece of information during long shoots. The Canon R, R3 and R5, with their top LCD screens, do not have this annoying “feature.”
TIP: End a Bulb Timer shoot prematurely by hitting the Shutter button. That feature is documented.
IN-CAMERA IMAGE STACKING
The R6 offers a menu option present on many recent Canon cameras: Multiple Exposure. The camera can take and internally stack up to 9 images, stacking them by using either Average (best for reducing noise) or Bright mode (best for star trails). An Additive mode also works for star trails, but stacking 9 images requires reducing the exposure of each image by 3 stops, say from ISO 1600 to ISO 200, as I did in the example below.
The result of the internal stacking is a raw file, with the option of also saving the component raws. While the options work very well, in all the cameras I’ve owned that offer such functions, I’ve never used them. I prefer to do any stacking needed later at the computer.
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.
Being a mirrorless camera, there is no reflex mirror to introduce vibration, and so no need for a mirror lockup function. The shutter can operate purely mechanically, with physical metal curtains opening and closing to start and end the exposure.
However, the default “out of the box” setting is Electronic First Curtain, where the actual exposure, even when on Bulb, is initiated electronically, but ended by the mechanical shutter. That’s good for reducing vibration, perhaps when shooting the Moon or planets through a telescope at high magnification.
In Mechanical, the physical curtains both start and end the exposure. It’s the mode I usually prefer, as I like to hear the reassuring click of the shutter opening. I’ve never found shutter vibration a problem when shooting deep sky images on a telescope mount of any quality.
In Mechanical mode the shutter can fire at up to 12 frames a second, or up to 20 frames a second in Electronic mode where both the start and end of the exposure happen without the mechanical shutter. That makes for very quiet operation, good for weddings and golf tournaments!
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.
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 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.
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.
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 ….
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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.
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.
• 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
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.
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.
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.
A new low-cost sky tracker promises to simplify not only tracking the sky but also taking time-lapses panning along the horizon. It works but …
If you are an active nightscape photographer chances are your social media feeds have been punctuated with ads for this new low-cost tracker from MoveShootMove.com.
For $200, much less than popular trackers from Sky-Watcher and iOptron, the SiFo unit (as it is labelled) offers the ability track the sky, avoiding any star trails. That alone would make it a bargain, and useful for nightscape and deep-sky photographers.
But it also has a function for panning horizontally, moving incrementally between exposures, thus the Move-Shoot-Move designation. The result is a time-lapse movie that pans along the horizon, but with each frame with the ground sharp, as the camera moves only between exposures, not during them.
Again, for $200 this is an excellent feature lacking in trackers like the Sky-Watcher Star Adventurer or iOptron SkyTracker. The Sky-Watcher Star Adventurer Mini does, however, offer both tracking and “move-shoot-move” time-lapse functions, but at a cost of $300 to $400 U.S., depending on accessories.
All these functions are provided in a unit that is light (weighing 700 grams with a tripod plate and the laser) and compact (taking up less space in your camera bag than most lenses). By comparison, the Star Adventurer Mini weighs 900 grams with the polar scope, while the original larger Star Adventurer is 1.4 kg, double the MSM’s weight.
Note, that the MSM’s advertised weight of 445 grams does not include the laser or a tripod plate, two items you need to use it. So 700 grams is a more realistic figure, still light, but not lighter than the competition by as much as you might be led to believe.
Nevertheless, the MSM’s small size and weight make it attractive for travel, especially for flights to remote sites. Construction is solid and all-metal. This is not a cheap plastic toy.
But does it work? Yes, but with several important caveats that might be a concern for some buyers.
What I Tested
I purchased the Basic Kit B package for $220 U.S., which includes a small case, a laser pointer and bracket for polar alignment (and with a small charger for the laser’s single 3.7-volt battery), and with the camera sync cable needed for time-lapse shooting.
I also purchased the new “button” model, not the older version that used a knob to set various tracking rates.
The ball head needed to go on top of the tracker is something you supply. The kit does come with two 3/8-inch stud bolts and a 3/8-to1/4-inch bushing adapter, for placing the tracker on tripods in the various mounting configurations I show below.
The first units were labelled as ‘SiFo,” but current units now carry the Gauda brand name. I’ll just call it the MSM.
I purchased the gear from the MSM website, and had my order fulfilled and shipped to me in Canada from China with no problems.
Tracking the Sky in Nightscapes
The attraction is its tracking function, allowing a camera to follow the sky and take exposures longer than any dictated by “500” or “NPF” Rules to avoid any star trailing.
Exposures can be a minute or more to record much more depth and detail in the Milky Way, though the ground will blur. But blending tracked sky exposures with untracked ground exposures gets around that, and with the MSM it’s easy to turn on and off the tracking motor, something not possible with the low-cost wind-up Mini Track from Omegon.
The illustrations and instructions (in a PDF well-hidden off the MSM Buy page) show the MSM mounted using the 1/4-20 bolt hole on the side of the unit opposite the LED-illuminated control panel. While this seems to be the preferredmethod, in the first unit I tested I found it produced serious mis-tracking problems.
With a Canon 6D MkII and 50mm f/1.4 lens (not a particularly heavy combination), the MSM’s gears would not engage and start tracking until after about 5 minutes. The first exposures were useless. This was also the case whenever I moved the camera to a new position to re-frame the scene or sky. Again, the first few minutes produced no or poor tracking until the gears finally engaged.
This would be a problem when taking tracked/untracked sets for nightscapes, as images need to be taken in quick succession. It’s also just plain annoying.
However, see the UPDATE at the end for the performance of a new Gauda-branded unit that was sent to me.
The solution was to mount the MSM using the 3/8-inch bolt hole on the back plate of the tracker, using the 1/4-20 adapter ring to allow it to attach to my tripod head. This still allowed me to tip the unit up to polar align it.
Tracking was now much more consistent, with only the first exposure usually badly trailed. But subsequent exposures all tracked, but with varying degrees of accuracy as I show below.
When used as a tracker, you need to control the camera’s exposure time with an external intervalometer you supply, to allow setting exposures over 30 seconds long.
The MSM offers a N and S setting, the latter for use in the Southern Hemisphere. A 1/2-speed setting turns the tracker at half the normal sidereal rate, useful for nightscapes as a compromise speed to provide some tracking while minimizing ground blurring.
For any tracker to track, its rotation axis has to be aimed at the Celestial Pole, near Polaris in the Northern Hemisphere, and near Sigma Octantis in the Southern Hemisphere.
I chose the laser pointer option for this, rather than the polar alignment scope. The laser attaches to the side of the MSM using a small screw-on metal bracket so that it points up along the axis of rotation, the polar axis.
The laser is labeled as a 1mw unit, but it is far brighter than any 1mw I’ve used. This does make it bright, allowing the beam to show up even when the sky is not dark. The battery is rechargeable and a small charger comes with the laser. Considering the laser is just a $15 option, it’s a bargain. But ….
UPDATE ADDED SEPTEMBER 1
Since I published the review, I have had the laser professionally tested, and it measured as having an output of 45 milliwatts. Yet it is labeled as being under 1 milliwatt. This is serious misrepresentation of the specs, done I can only assume to circumvent import restrictions. In Canada it is now illegal to import, own, or use any green laser over 5 milliwatts, a power level that would be sufficient for the intended use of polar aligning. 45mw is outright illegal.
So be warned, use of this laser will be illegal in some areas. And use of any green laser will be illegal close to airports, and outlawed entirely in some jurisdictions such as Australia, a fact the MSM website mentions.
The legal alternative is the optical polar alignment scope. I already have several of those, but my expectation that I could use one I had with the same bracket supplied with the laser were dashed by the fact that the bracket’s hole is too narrow to accept any of the other polar alignment scopes I have, which are all standard items. I you want a polar scope, buy theirs for $70.
However, if you can use it where you live, the laser works well enough, allowing you to aim the tracker at the Pole just by eye. For the wide lenses the tracker is intended to be used with, eyeball alignment proved good enough.
Just be very, very careful not to accidentally look down the beam. Seriously. It is far too easy to do by mistake, but doing so could damage your eye in moments.
Tracking the Sky in Deep-Sky Images
How well does the MSM actually track? In tests of the original SiFo unit I bought, and in sets of exposures with 35mm, 50mm, and 135mm lenses, and with the tracker mounted on the back, I found that 25% to 50% of the images showed mis-tracking. Gear errors still produced slightly trailed stars. This gear error shows itself more as you shoot with longer focal lengths.
The MSM is best for what it is advertised as — as a tracker for nightscapes with forgiving wide-angle lenses in the 14mm to 24mm range. With longer lenses, expect to throw away a good number of exposures as unusable. Take twice as many as you think you might need.
With a 135mm lens taking Milky Way closeups, more than half the shots were badly trailed. Really badly trailed. This is not from poor polar alignment, which produces a gradual drift of the frame, but from errors in the drive gears, and random errors at that, not periodic errors.
To be fair, this is often the case with other trackers as well. People always want to weight them down with heavy and demanding telephotos for deep-sky portraits, but that’s rarely a good idea with any tracker. They are best with wide lenses.
That said, I found the MSM’s error rate and amount to be much worse than with other trackers. With the Star Adventurer models and a 135mm lens for example, I can expect only 20% to 25% of the images to be trailed, and even then rarely as badly as what the MSM exhibited.
See the UPDATE at the end for the performance of the replacement Gauda-branded unit sent to me with the promise of much improved tracking accuracy.
Yes, enough shots worked to be usable, but it took using a fast f/2 lens to keep exposure times down to a minute to provide that yield. Users of slow f/5.6 kit-zoom lenses will struggle trying to take deep-sky images with the MSM.
In short, this is a low-cost tracker and it shows. It does work, but not as well as the higher-cost competitors. But restrict it to wide-angle lenses and you’ll be fine.
Panning the Ground
The other mode the MSM can be used in is as a time-lapse motion controller. Here you mount the MSM horizontally so the camera turns parallel to the horizon (or it can be mounted vertically for vertical panning, a mode I rarely use and did not test).
This is where the Move-Shoot-Move function comes in.
The supplied Sync cable goes from the camera’s flash hot shoe to the MSM’s camera jack. What happens is that when the camera finishes an exposure it sends a pulse to the MSM, which then quickly moves while the shutter is closed by the increment you set.
There is a choice of 4 speeds, marked in degrees-per-move: 0.05°, 0.2°, 0.5°, and 1.0°. For example, as the movie below shows, taking 360 frames at the 1° speed results in a complete 360° turn.
The MSM does the moving, but all the shutter speed control and intervals must be set using a separate intervalometer, either one built into the camera, or an outboard hardware unit. The MSM does not control the camera shutter. In fact, the camera controls the MSM.
Intervals should be set to be about 2 seconds longer than the shutter speed, to allow the MSM to perform its move and settle.
This connection between the MSM and camera worked very well. It is unconventional, but simple and effective.
Too Slow or Too Fast
The issue is the limited choice of move speeds. I found the 0.5° and 1° speeds much too fast for night use, except perhaps for special effects in urban cityscapes. Even in daytime use, when exposure times are very short, the results are dizzying, as I show below.
Even the 0.2°-per-move speed I feel is too fast for most nightscape work. Over the 300 exposures one typically takes for a time-lapse movie, that speed will turn the MSM (300 x 0.2°) = 60 degrees. That’s a lot of motion for 300 shots, which will usually be rendered out at 24 or 30 frames per second for a clip that lasts 10 to 12 seconds. The scene will turn a lot in that time.
On the other hand, the 0.05°-per-move setting is rather slow, producing a turn of (300 x 0.05°) = 15° during the 300 shots.
That works, but with all the motion controllers I’ve used — units that can run at whatever speed they need to get from the start point to the end point you set — I find a rate of about 0.1° per move is what works best for a movie that provides the right amount of motion. Not too slow. Not too fast. Just right.
UPDATE ADDED DECEMBER 21, 2019
From product photos on the MoveShootMove.com website now it appears that the tracker is now labeled MSM, as it should have been all along.
Most critically, perhaps in response to this review and my comments here, the time-lapse speeds have been changed to 0.05, 0.075, 0.1 and 0.125 degrees per move, adding the 0.1°/move speed I requested below and deleting the overly fast 0.5° and 1.0° speeds.
Plus it appears the new units have the panel labels printed the other way around so they are not upside down for most mounting situations.
I have not tested this new version, but these speeds sound much more usable for panning time-lapses. Bravo to MSM for listening!
Following the Sky in a Time-Lapse
The additional complication is trying to get the MSM to also turn at the right rate to follow the sky — for example, to keep the galaxy core in frame during the time-lapse clip. I think doing so produces one of the most effective time-lapse sequences.
But to do that with any device requires turning at a rate of 15° per hour, the rate the sky moves from east to west.
Because the MSM provides only set fixed speeds, the only way you have of controlling how much it moves over a given amount of time, such as an hour, is to vary the shutter speed.
I found that to get the MSM to follow the Milky Way in a time-lapse using the 0.05° rate and shooting 300 frames required shooting at a shutter speed of 12 seconds. No more, no less.
Do the Math
Where does that number come from?
At its rate of 0.05°/move, the MSM will turn 15° over 300 shots. The sky moves 15° in one hour, or 3600 seconds. So to fit 300 shots into 3600 seconds means each shot has to be no longer than (3600/300) = 12 seconds long.
The result works, as I show in the sampler movie.
But 12 seconds is a rather short shutter speed on a dark, moonless night with the Milky Way.
For properly exposed images you would need to shoot at very fast apertures (f/1.4 to f/2) and/or high and noisy ISO speeds. Neither are optimal. But they are forced upon you by the MSM’s restricted rates.
Using the faster 0.2° rate (of the original model) yields a turn of 60° over 300 shots. That’s four hours of sky motion. So each exposure now has to be 48 seconds long for the camera to follow the sky, four times longer because the drive rate is now four times faster.
A shutter speed of 48 seconds is a little too long in my opinion. Stars in each frame will trail. Plus a turn of 60° over 300 shots is quite a lot, producing a movie that turns too quickly.
By far the best speed for motion control time-lapses would be 0.1° per move. That would allow 24-second exposures to follow the sky, allowing a stop less in aperture or ISO speed. (DECEMBER 21 UPDATE: That speed seems to now be offered.)
Yes, having only a limited number of pre-wired speeds does make the MSM much easier to program than devices like the Star Adventurer Mini or SYRP Genie Mini that use wireless apps to set their functions. No question, the MSM is better suited to beginners who don’t want to fuss with lots of parameters.
As it is, getting a decent result requires some math and juggling of camera settings to make up for the MSM’s limited choices of speeds.
Time-Lapse Movie Examples
This compilation shows examples of daytime time-lapses taken at the fastest and dizzying 0.5° and 1.0° speeds, and night time-lapses taken at the slower speeds. The final clip is taken at 0.05°/move and with 12-second exposures, a combination that allowed the camera to nicely follow the Milky Way, albeit at a slow pace. Taking more than the 300 frames used here would have produced a clip that turned at the same rate, but lasted longer.
The MSM is powered off an internal rechargeable battery, which can be charged from any 5-volt charger you have from a mobile phone.
The MSM uses a USB-C jack for the power cable, but a USB-A to USB-C cord is supplied, handy as you might not have one if you don’t have other USB-C devices.
The battery lasted for half a dozen or more 300-shot time-lapses, enough to get you through at least 2 or 3 nights of shooting. However, my testing was done on warm summer nights. In winter battery life will be less.
While the built-in battery is handy, in the field should you find battery level low (the N and S switches blink as a warning) you can’t just swap in fresh batteries. Just remember to charge up before heading out. Alternatively, it can be charged from an external 5V battery pack such as used to prolong cell phone life.
The MSM does not offer, nor does it promise, any form of automated panorama shooting. This is where the device turns by, say, 15° to 45° between shots, to shoot the segments for a still-image panorama. More sophisticated motion controllers from SYRP and Edelkrone offer that function, including the ability to mate two devices for automated multi-tier panoramas.
Nor does the MSM offer the more advanced option of ramping speeds up and down at the start and end of a time-lapse. It moves at a constant rate throughout.
While some of the shortcomings could perhaps be fixed with a firmware update, there is no indication anywhere that its internal firmware can be updated through the USB-C port.
UPDATE ADDED OCTOBER 7, 2019
Since I published the review, MSM saw the initial test results and admitted that the earlier units like mine (ordered in June) exhibited large amounts of tracking error. They sent me a replacement unit, now branded with the Gauda label. According to MSM it contains a more powerful motor promised to improve tracking accuracy and making it possible to take images with lenses as long as 135mm.
I’m sorry to report it didn’t.
In tests with the 135mm lens the new, improved MSM still showed lots of tracking error, to the point that images taken with a lens as long as this were mostly unusable.
Tap or click on the images to download full-res versions.
The short movie above takes the full-frame images from the zenith set of 24 frames taken over 48 minutes and turns them into a little time-lapse. It shows how the mechanism of the MSM seems to be wobbling the camera around in a circle, creating the mis-tracking.
Comparison with the Star Adventurer
As a comparison, the next night I used a Sky-Watcher Star Adventurer (the full-size model not the Mini) to shoot the same fields in the northeast and overhead with the same 135mm lens and with the same ball-head, to ensure the ball-head was not at fault. Here are the results:
The Star Adventurer performed much better. Most images were well-tracked. Even on those frames that showed trailing, it was slight. The Star Adventurer is a unit you can use to take close-ups of deep-sky fields with telephoto lenses, if that’s your desire.
By contrast, the MSM is best used — indeed, I feel can only be used practically — with wide-angle lenses and with exposures under 2 minutes. Here’s a set taken with a 35mm lens, each for 2 minutes.
With the more forgiving 35mm lens, while more images worked, the success rate was still only 50%.
What I did not see with the new Gauda unit was the 5-minute delay before the gears meshed and tracking began. That issue has been resolved by the new, more powerful motor. The new Gauda model does start tracking right away.
But it is still prone to significant enough drive errors that stars are often trailed even with a 35mm lens (this was on a full-frame Canon 6D MkII).
UPDATED CONCLUSIONS (December 21, 2019)
The MSM tracker is low-cost, well-built, and compact for easy packing and travel. It performs its advertised functions well enough to allow users to get results, either tracked images of the Milky Way and constellations, or simple motion-control time-lapses.
But it is best used — indeed I would suggest can only be used — with wide-angle lenses for tracked Milky Way nightscapes. Even then, take more shots than you think you need to be sure enough are well-tracked and usable.
It can also be used for simple motion-control time-lapses, provided you do to the math to get it to turn by the amount you want, working around the too-slow or too-fast speeds. The new 0.1° per move speed (added in models as of December 2019) seems a reasonable rate for most time-lapses.
However, I think aspiring time-lapse photographers will soon outgrow the MSM’s limitations for motion-control sequences. But it can get you started.
If you really value its compactness and your budget is tight, the MSM will serve you well enough for tracked nightscape shooting with wide-angle lenses.
But if you wish to take close-ups of starfields and deep-sky objects with longer lenses, consider a unit like the Sky-Watcher Star Adventurer for its lower tracking errors. Or the Star Adventurer Mini for its better motion-control time-lapse functions.
But what about lenses for the Sony? Here’s one ideal for astrophotography.
Made for Sony e-mount cameras, the Venus Optics 15mm f/2 Laowa provides excellent on- and off-axis performance in a fast and compact lens ideal for nightscape, time-lapse, and wide-field tracked astrophotography with Sony mirrorless cameras. (UPDATE: Venus Optics has announced versions of this lens for Canon R and Nikon Z mount mirrorless cameras.)
I use it a lot and highly recommend it.
Size and Weight
While I often use the a7III with my Canon lenses by way of a Metabones adapter, the Sony really comes into its own when matched to a “native” lens made for the Sony e-mount. The selection of fast, wide lenses from Sony itself is limited, with the new Sony 24mm G-Master a popular favourite (I have yet to try it).
However, for much of my nightscape shooting, and certainly for auroras, I prefer lenses even wider than 24mm, and the faster the better.
Aurora over Båtsfjord, Norway. This is a single 0.8-second exposure at f/2 with the 15mm Venus Optics lens and Sony a7III at ISO 1600.
The Laowa 15mm f/2 from Venus Optics fills the bill very nicely, providing excellent speed in a compact lens. While wide, the Laowa is a rectilinear lens providing straight horizons even when aimed up, as shown above. This is not a fish-eye lens.
The Venus Optics 15mm realizes the potential of mirrorless cameras and their short flange distance that allows the design of fast, wide lenses without massive bulk.
While compact, at 600 grams the Laowa 15mm is quite hefty for its size due to its solid metal construction. Nevertheless, it is half the weight of the massive 1250-gram Sigma 14mm f/1.8 Art. The Laowa is not a plastic entry-level lens, nor is it cheap, at $850 from U.S. sources.
For me, the Sony-Laowa combination is my first choice for a lightweight travel camera for overseas aurora trips
However, this is a no-frills manual focus lens. Nor does it even transfer aperture data to the camera, which is a pity. There are no electrical connections between the lens and camera.
However, for nightscape work where all settings are adjusted manually, the Venus Optics 15mm works just fine. The key factor is how good are the optics. I’m happy to report that they are very good indeed.
Testing Under the Stars
To test the Venus Optics lens I shot “same night” images, all tracked, with the Sigma 14mm f/1.8 Art lens, at left, and the Rokinon 14mm SP (labeled as being f/2.4, at right). Both are much larger lenses, made for DSLRs, with bulbous front elements not able to accept filters. But they are both superb lenses. See my test report on these lenses published in 2018.
The next images show blow-ups of the same scene (the nightscape shown in full below, taken at Dinosaur Provincial Park, Alberta), and all taken on a tracker.
I used the Rokinon on the Sony a7III using the Metabones adapter which, unlike some brands of lens adapters, does not compromise the optical quality of the lens by shifting its focal position. But lacking a lens adapter for Nikon-to-Sony at the time of testing, I used the Nikon-mount Sigma lens on a Nikon D750, a DSLR camera with nearly identical sensor specs to the Sony.
Above is a tracked image (so the stars are not trailed, which would make it hard to tell aberrations from trails), taken wide open at f/2. No lens correction has been applied so the vignetting (the darkening of the frame corners) is as the lens provides.
As shown above, when used wide open at f/2 vignetting is significant, but not much more so than with competitive lenses with much larger lenses, as I compare below.
And the vignetting is correctable in processing. Adobe Camera Raw and Lightroom have this lens in their lens profile database. That’s not the case with current versions (as of April 2019) of other raw developers such as DxO PhotoLab, ON1 Photo RAW, and Raw Therapee where vignetting corrections have to be dialled in manually by eye.
When stopped down to f/2.8 the Laowa “flattens” out a lot for vignetting and uniformity of frame illumination. Corner aberrations also improve but are still present. I show those in close-up detail below.
Above, I compare the vignetting of the three lenses, both wide open and when stopped down. Wide open, all the lenses, even the Sigma and Rokinon despite their large front elements, show quite a bit of drop off in illumination at the corners.
The Rokinon SP actually seems to be the worst of the trio, showing some residual vignetting even at f/2.8, while it is reduced significantly in the Laowa and Sigma lenses. Oddly, the Rokinon SP, even though it is labeled as f/2.4, seemed to open to f/2.2, at least as indicated by the aperture metadata.
Above I show lens sharpness on-axis, both wide open and stopped down, to check for spherical and chromatic aberrations with the bright blue star Vega centered. The red box in the Navigator window at top right indicates what portion of the frame I am showing, at 200% magnification in Photoshop.
On-axis, the Venus Optics 15mm shows stars just as sharply as the premium Sigma and Rokinon lenses, with no sign of blurring spherical aberration nor coloured haloes from chromatic aberration.
Focusing is precise and easy to achieve with the Sony on Live View. My unit reaches sharpest focus on stars with the lens set just shy of the middle of the infinity symbol. This is consistent and allows me to preset focus just by dialing the focus ring, handy for shooting auroras at -35° C, when I prefer to minimize fussing with camera settings, thank you very much!
The Laowa and Sigma lenses show similar levels of off-axis coma and astigmatism, with the Laowa exhibiting slightly more lateral chromatic aberration than the Sigma. Both improve a lot when stopped down one stop, but aberrations are still present though to a lesser degree.
However, I find that the Laowa 15mm performs as well as the Sigma 14mm Art for star quality on- and off-axis. And that’s a high standard to match.
The Rokinon SP is the worst of the trio, showing significant elongation of off-axis star images (they look like lines aimed at the frame centre), likely due to astigmatism. With the 14mm SP, this aberration was still present at f/2.8, and was worse at the upper right corner than at the upper left corner, an indication to me that even the premium Rokinon SP lens exhibits slight lens de-centering, an issue users have often found with other Rokinon lenses.
Real-World Examples – The Milky Way
The fast speed of the Laowa 15mm is ideal for shooting tracked wide-field images of the Milky Way, and untracked camera-on-tripod nightscapes and time-lapses of the Milky Way.
Image aberrations are very acceptable at f/2, a speed that allows shutter speed and ISO to be kept lower for minimal star trailing and noise while ensuring a well-exposed frame.
Real World Examples – Auroras
Where the Laowa 15mm really shines is for auroras. On my trips to chase the Northern Lights I often take nothing but the Sony-Laowa pair, to keep weight and size down.
Above is an example, taken from a moving ship off the coast of Norway. The fast f/2 speed (I wish it were even faster!) makes it possible to capture the Lights in only 1- or 2-second exposures, albeit at ISO 6400. But the fast shutter speed is needed for minimizing ship movement.
The Sony also excels at real-time 4K video, able to shoot at ISO 12,800 to 51,200 without excessive noise.
Aurora Reflections from Alan Dyer on Vimeo.
The Sky is Dancing from Alan Dyer on Vimeo.
The Northern Lights At Sea from Alan Dyer on Vimeo.
Click through to see the posts and the videos shot with the Venus Optics 15mm.
As an aid to video use, the aperture ring of the Venus Optics 15mm can be “de-clicked” at the flick of a switch, allowing users to smoothly adjust the iris during shooting, avoiding audible clicks and jumps in brightness. That’s a very nice feature indeed.
In all, I can recommend the Venus Optics Laowa 15mm lens as a great match to Sony mirrorless cameras, for nightscape still and video shooting. UPDATE: Versions for Canon R and Nikon Z mount mirrorless cameras will now be available.
In a technical blog I compare the new Canon 6D Mark II camera with its predecessor, the Canon 6D, with the focus on performance for nightscape astrophotography.
No pretty pictures in this blog I’m afraid! This is a blog for gear geeks.
The long-awaited Canon 6D Mark II camera is out, replacing the original 6D after that camera’s popular 5-year reign as a prime choice among astrophotographers for all kinds of sky images, including nightscapes and time-lapses.
As all new cameras do, the 6D Mark II is currently fetching a full list price of $2000 U.S. Eventually it will sell for less. The original 6D, introduced in 2012 at that same list price, might still be available from many outlets, but for less, likely below $1500 US.
Shown on the left, above, the 6D Mark II is similar in size and weight to the original 6D.
However, the new Mark II offers 6240 x 4160 pixels for 26 megapixels, a bump up in resolution over the 5472 x 3648 20-megapixel 6D. The pixel pitch of the Mark II sensor is 5.7 microns vs. 6.6 microns for the 6D.
One difference is that the port for a remote release is now on the front, but using the same solid 3-pin N3 connector as the 6D and other full-frame Canons. That makes it compatible with all external controllers for time-lapse shooting.
TESTING FOR THE NIGHT
My interest is in a camera’s performance for long-exposure astrophotography, with images taken at high ISO settings. I have no interest in auto-focus performance (we shoot at night with focus set manually), nor how well a camera works for high-speed sports shooting.
To test the Mark II against the original 6D I took test shots at the same time of a high-contrast moonlit scene in the backyard, using a range of ISO speeds typical of nightscape scenes.
The comparisons show close-ups of a scene shown in full in the smaller inset screen.
The key characteristic of interest for night work is noise. How well does the camera suppress the noise inherent in digital images when the signal is boosted to the high ISO settings we typically use?
This set shows the 6D MkII at five ISOs, from ISO 1600 all the way up to the seldom-used ISO 25,600, all shot in Raw, not JPG. In all cases, no noise reduction was applied in later processing, so the results do look worse than what processed images would.
Click or tap on all images to expand each image to full screen for closer inspection.
This set shows the same range of ISOs with the original 6D. All were taken at the same aperture, f/2.8, with a 35mm lens. Exposures were halved for each successive bump up in ISO speed, to ensure equally exposed images.
Comparing the sets, the 6D MkII shows a much greater tendency to exhibit a magenta cast in the shadows at very high ISOs, plus a lower contrast in the shadows at increasing ISOs, and slightly more luminance noise than the 6D.
How much more noise the 6D MkII exhibits is demonstrated here.
To me, visually, the MkII presents about 1/2 stop, or EV, worse noise than the 6D.
In this example, the MkII exhibits a noise level at ISO 3200 (a common nightscape setting) similar to what the 6D does if set between ISO 4000 and 5000 – about 1/2 stop worse noise.
Frankly, this is surprising.
Yes, the MkII has a higher pixel count and therefore smaller pixels (5.7 microns in this case) that are always more prone to noise. But in the past, advances to the in-camera signal processing has prevented noise from becoming worse, despite increasing pixel count, or has even produced an improvement in noise.
For example, the 2012-vintage 6D is better for noise than Canon’s earlier 2008-era 5D MkII model by about half a stop, or EV.
After five years of camera development I would have expected a similar improvement in the 6D MkII. After all, the 6D MkII has Canon’s latest DIGIC 7 processor, vs. the older 6D’s DIGIC 5+.
Instead, not only is there no noise improvement, the performance is worse.
That said, noise performance in the 6D MkII is still very good, and better than you’ll get with today’s 24 megapixel cropped-frame cameras with their even smaller 4 micron pixels. But the full frame 6D MkII doesn’t offer quite as much an improvement over cropped-frame cameras as does the five-year-old 6D.
In the previous sets all the images were well-exposed, as best they could be for such a contrasty scene captured with a single exposure.
What happens when Raw images are underexposed, then boosted later in exposure value in processing?
This is not an academic question, as that’s often the reality for nightscape images where the foreground remains dark. Bringing out detail in the shadows later requires a lot of Shadow Recovery or increasing the Exposure. How well will the image withstand that work on the shadows?
To test this, I shot a set of images at the same shutter speed, but at successively slower ISOs, from a well-exposed ISO 3200, to a severely underexposed ISO 100. I then boosted the Exposure setting later in Raw processing by an amount that compensated for the level of underexposure in the camera, from a setting of 0 EV at ISO 3200, to a +5 EV boost for the dark ISO 100 shots.
This tests for a camera’s “ISO Invariancy.” If a camera has a sensor and signal processing design that is ISO invariant, a boosted underexposed image at a slow ISO should look similar to a normally exposed image at a high ISO.
You’re just doing later in processing what a camera does on its own in-camera when bumping up the ISO.
But cameras that use ISO “variant” designs suffer from increased noise and artifacts when severely underexposed images are boosted later in Raw processing.
The Canon 6D and 6D MkII are such cameras.
This set above shows the results from the 6D Mark II. Boosting underexposed shadows reveals a lot of noise and a severe magenta cast.
These are all processed with Adobe Camera Raw, identical to the development engine in Adobe Lightroom.
This set above shows the results from the 6D. The older camera, which was never great for its lack of ISO Invariancy performance, is still much better than the new Mark II.
Effectively, this is the lack of dynamic range that others are reporting when testing the 6D MkII on more normal daytime images. It really rears its ugly head in nightscapes.
The lesson here is that the Mark II needs to be properly exposed as much as possible.
Don’t depend on being able to extract details later from the shadows. The adage “Expose to the Right,” which I explain at length in my Nightscapes eBook, applies in spades to the 6D MkII.
DARK FRAME BUFFER
All the above images were taken with Long Exposure Noise Reduction (LENR) off. This is the function that, when turned on, forces the camera to take and internally subtract a dark frame – an image of just the noise – reducing thermal noise and discolouration in the shadows.
A unique feature of Canon full-frame cameras is that when LENR is on you can take several exposures in quick succession before the dark frame kicks in and locks up the camera. This is extremely useful for deep-sky shooting.
The single dark frame then gets applied to the buffered “light frames.”
The 6D Mark II, when in either Raw or in Raw+JPG can take 3 shots in succession. This is a downgrade from the 6D which can take 4 shots when in Raw+JPG. Pity.
ADOBE CAMERA RAW vs. DIGITAL PHOTO PROFESSIONAL
My next thought was that Adobe Camera Raw, while it was reading the Mark II files fine, might not have been de-Bayering or developing them properly. So I developed the same image with both Raw developers, Adobe’s and Canon’s latest version of their own Digital Photo Professional (DPP).
Here I did apply a modest and approximately similar level of noise reduction to both images:
In ACR: Color at 25, Luminosity at 40, with Sharpness at 25
In DPP: Chrominance at 8, Luminosity at 8, with Sharpness at 2
Yes, DPP did do a better job at eliminating the ugly magenta cast, but did a much worse job at reducing overall noise. DPP shows a lot of blockiness, detail loss, and artifacts left by the noise reduction.
Adobe Camera Raw and/or Lightroom remain among the best of many Raw developers.
A new feature the 6D Mark II offers is the ability to shoot and stack images in-camera. It can either “Add” the exposure values, or, most usefully, “Average” them, as shown here.
Other newer Canon DSLRs also offer this feature, notably the 7D MkII, the 5D MkIV, the 5Ds, and even the entry-level 80D. So the 6D MkII is not unique. But the feature was not on the 6D.
Here’s the benefit.
The left image is a single exposure; the middle is an average stack of 4 exposures stacked in camera; the right image an average stack of 9 exposures, the maximum allowed.
Noise smooths out a lot, with less noise the more images you stack. The result is a single Raw file, not a JPG. Excellent!
While this kind of stacking can be done later in processing in Photoshop, or in any layer-based program, many people might find this in-camera function handy.
Except, as you can see, the sky will exhibit star trails, and not as well defined as you would get from stacking them with a “Lighten” blend mode, as all star trail stacking routines use.
So this averaging method is NOT the way to do star trails. The Mark II does not offer the Brighten mode some other new Canons have that does allow for in-camera star trail stacking. Again, a pity in a camera many will choose for astrophotography.
Nevertheless, the Average mode is a handy way to create foreground landscapes with less noise, which then have to be composited later with a sky image or images.
On the left, below, the Mark II has a nearly identical layout of buttons and controls to the 6D on the right. So owners of the older model will feel right at home with the Mark II. That’s handy, as we astrophotographers work in the dark by feel!
Of course the big new feature, a first for Canon in a full-frame camera, is the Mark II’s fully articulated screen. It flips out, tilts, and even flips around to face forward. This is super-great for all astrophotography, especially when conducted by aging photographers with aching backs!
And the screen, as with the entry-level cropped-frame Canons, is a touch screen. For someone who hasn’t used one before – me! – that’ll take some getting used to, if only in just remembering to use it.
And it remains to be seen how well it will work in the cold. But it’s great to have.
Like other late-model Canon DSLRs, the 6D MkII has a built-in intervalometer. It works fine but is useable only on exposures with internally set shutter speeds up to 30 seconds.
However, setting the Interval so it fires the shutter with a minimal gap of 1 second between shots (our usual requirement for night time-lapses) is tricky: You have to set the interval to a value not 1 second, but 2 to 3 seconds longer than the shutter speed. i.e. an exposure of 30 seconds requires an interval of 33 seconds, as shown above. Anything less and the camera misses exposures.
Why? Well, when set to 30 seconds the camera actually takes a 32-second exposure. Surprise!
Other cameras I’ve used and tested with internal intervalometers (Nikon and Pentax) behave the same way. It’s confusing, but once you are used to it, the intervalometer works fine.
Except … the manual suggests the only way to turn it off and stop a sequence is to turn off the camera. That’s crude. A reader pointed out that it is also possible to stop a time-lapse sequence by hitting the Live View Start/Stop button. However, that trick doesn’t work on sequences programmed with only a second between frames, as described above. So stopping a night time-lapse is inelegant to say the least. With Nikons you can hold down the OK button to stop a sequence, with the option then of restarting it if desired.
Also, the internal Intervalometer cannot be used for exposures longer than 30 seconds. Again, that’s the case with all in-camera intervalometers in other models and brands.
As with many other new Canons, the Mark II has a Bulb Timer function.
When on Bulb you can program in exposure times of any length. That’s a nice feature that, again, might mean an external intervalometer is not needed for many situations.
A new feature I like is the greatly expanded information when reviewing an image.
One of the several screens you can scroll to shows whether you have shot that image with Long Exposure Noise Reduction on or not.
Excellent! I have long wanted to see that information recorded in the metadata. Digital Photo Professional also displays that status, but not Adobe Camera Raw/Lightroom.
While this has been a long report, this is an important camera for us astrophotographers.
I wish the news were better, but the 6D Mark II is somewhat of a disappointment for its image quality. It isn’t bad. It’s just that it isn’t any better than than the older 6D, and in some aspects is worse.
Canon has clearly made certain compromise decisions in their sensor design. Perhaps adding in the Dual-Pixel Autofocus for rapid focusing in Movie Mode has compromised the signal-to-noise ratio. That’s something only Canon can explain.
But the bottom-line recommendations I can offer are:
If you are a Canon user looking to upgrade to your first full-frame camera, the 6D Mark II will provide a noticeable and welcome improvement in noise and performance over a cropped-frame model. But an old 6D, bought new while they last in stock, or bought used, will be much cheaper and offer slightly less noise. But the Mark II’s flip-out screen is very nice!
If you are a current 6D owner, upgrading to a Mark II will not get you better image quality, apart from the slightly better resolution. Noise is actually worse. But it does get you the flip-out screen. I do like that!
If you are not wedded to Canon, but want a full-frame camera for the benefits of its lower noise, I would recommend the Nikon D750. I have one and love it. I have coupled it with the Sigma Art series lenses. I have not used any of the Sony a7-series Mirrorless cameras, so cannot comment on their performance, but they are popular to be sure.
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?
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.
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.
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?
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?
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.
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.
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
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
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.