R6 - for Astrophotography? Yup. (PICS) Locked

knutte wrote:

Thank you for your post, I had (reluctantly) planned to get R5 but the price is making me hesitant and was thinking the R6 might be stepdown from the R5 in respect to astro but I'm rethinking my order.

I was considering the R5 several times but the cost difference vs the features/specs didn't appeal to me.  I almost think that Canon should have crippled the R6 in some way to get people to flip over to the R5.  With the specs being so similar (except for the sensor). it's got a lot of people to become hesitant.
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The R5 is a 'higher megapixel camera' so the pixels/light-wells are much smaller on this sensor. They have to be smaller in order to fit so many of them onto the same sized sensor. By comparison, the pixels/light-wells on the R6 are physically larger according to Canon reps... and are therefore likely to be more suited to astrophotography. But this doesn't mean the R5 can't do it.. and you can see an example from an R5 user here (see link immediately below) ... but note the magic words in his description of the experience: "If I primarily shot astrophotography I'm not sure the upgrade would be quite warranted..."
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https://fstoppers.com/astrophotography/astrophotography-canon-r5-how-does-it-perform-506450

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Edit: I have just discovered that the image taken above was the result of 17 stacked individual shots from the R5 taken at ISO 3200 on an f/1.8 lens.  If that's what was needed to pull out the details in this shot, and he was shooting in a dark sky location (he was), then the R5 would appear to struggle a little more with this type of photography (which makes perfect sense).  He seemed to find the results from the R5 were similar to those from the 5D IV.  He was also keen to extract more detail than he was getting with individual short-exposure shots.  But it's important to note that when exposing in bright skies, you sometimes need to stop down and try to stack just to resolve the scene properly without blowing the exposure out.
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No doubt one of the numerous R5 users here can take a couple of shots and post about their experiences here. I'd be interested to get an honest opinion from an R5 owner from DPreview's forums on the subject.  The samples I've seen online from the R5 (relating to astrophotography) have all been processed aggressively, shot with Tungsten WB and appear to be noisy... or have clear star movement, indicating longer than ideal exposure times.  You can get away with this more if you're just posting to Instagram.  It's hard to say what the performance is like based on these observations.  We don't know how much the images were edited or compressed before posting them online.
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To anyone with an R5, I'd be very interested in hearing how those tightly packed pixels perform on the same sized sensor.  Canon thinks the sensors with 30MP (EOS R/Ra) can "average out the noise" in a way that was unexpected and pleasing - so perhaps this benefit rolls on towards the R5?.  I am often asked to recommend different cameras for astro to friends or associates so the information is important to me. 
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I enjoyed using the R6 so much that I'd be prepared to try and shoot some astro landscapes from a (hopefully) darker location using different settings from a new location.  I have three days of cloud and rain coming up so if you can wait almost two weeks from now until the weather clears, I might be tempted to try something different.
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From my observations with the R6 and the Ra, I'd comfortably state that the Ra is considerably better for astrophotography than any of the other R camera (or DSLR) due to greater noise control (which extends further than the pixel limitation) and enhanced wavelength sensitivity.