...certainly not as stark a difference as my first example. Maybe that one is invalid. This example, however, does show that the 7D is still picking up more subtle details and nuances of color. The differences are not stark, but they do exist.
Thanks. This revision addresses the issue about which dak723 and I were commenting (namely, a method biased in favor of the 7D). The difference you're showing here aligns more closely with what I've seen under similar conditions, i.e., at low ISO. I wonder what you'd find empirically at ISO 1600 or ISO 6400...
I dunno, I guess I can try. The moon has a LOT of dynamic range. In general, a hell of a lot more dynamic range than is possible to capture even with 14 stops of DR. So I try to shoot at as low an ISO as possible. On a Canon camera, ISO 100-400 are roughly the same, there is only a fraction of a stop difference in DR between them. I chose ISO 200 in this case, as I noticed that banding was occurring at ISO 400 on the 7D.
At ISO 1600 and 6400, the biggest single problem would simply be not having enough dynamic range to differentiate fine nuances of detail, due to quantization noise. That is one area where bigger pixels do help...they reduce quantization noise, so shadow detail is better at higher ISO.
You can't think of photographing the moon as photographing something in the dark, though. It's reflecting the sun. It is an EXTREMELY bright subject, and it has massive dynamic range. (I mean, think about it...how many stops of DR do you think you would need to resolve clean, crisp detail on the dark side while simultaneously resolving clean, crisp detail in the brightest crater hotspots on the light side? At least 20 stops...although, I've tried merging a bunch of moon frames together into a 32-bit float HDR for processing in ACR...and the shadowed site was STILL too noisy...)
The issues you describe make sense. However, in your original post you made the following point:
A common reach-limited use case is bird photography. Similar to the moon, it can be difficult to get close to and fully extract all the detail from a small songbird, shorebirds, and shy waders or waterfowl.
I believe that bird photography is a much more common reach-limited use case than lunar photography. It would be useful to establish how applicable a demonstration of the 'reach advantage' in lunar photography is to bird photography, which comprises a broader range of conditions, frequently including subjects far less bright and/or a need for high shutter speeds.
Do you find that in general bird photography has the same demands as lunar photography in terms of DR? What fraction of your bird images are taken at ISO 200? A look at my bird collection shows that the median for the library is ISO 1600.
Regardless of demonstrated broad applicability to bird photography as a use case, your efforts with the moon shots are certainly appreciated!
I agree, the moon is not the same as birds. It's simply that it is a perfect reach-limited subject that doesn't zip around, constantly on the move (well, it moves, but I can track it).
Regarding birds and DR...to be honest, I have not found that dynamic range is the issue when photographing birds. Not in the sense that I've ever come across a scene where I really felt the scene contained considerably more dynamic range than my sensor could handle, even at high ISO. Usually, my bird photography is between ISO 400 and 1600, however there have been times when I've really pushed the ISO, and still gotten great results (even with the 7D...such as the Black-Crowned Night Heron photo I've shared a few times.)
One of the things I always strive for in my bird photography is getting the right angles. The right angle from me to the bird, the right angles between the bird, myself, and the sun, and the right angle of the bird's head to it's body. Those are actually very critical aspects of bird photography. When you get the right angles, then the subject is usually fully illuminated (even if it's overcast, the light still primarily comes from a certain direction) and because your angle to the bird avoids any major DR swings (i.e. having half the bird in light and half the bird on dark shadow, such as when the sun is off to your left or right, rather than behind you over one of your shoulders), even at ISO 6400 you still usually have enough dynamic range to capture the subject without issues.
There have been a few occasions when I've photographed dark birds with small very light colored spots (i.e. Belted Duck) or light birds with very dark parts (i.e. Bufflehead) where I am sometimes forced to use a lower ISO (which, to me, is probably ISO 800, maybe 400). With the 7D, sometimes ISO 400 could be problematic because of it's vertical banding issue. With the 5D III, I don't suspect it will be a problem, however for these birds, I'll probably be at 1200mm f/8, so I'd probably be using ISO 1600 instead.
Anyway, when it comes to bird and wildlife photography, dynamic range is just not an issue. It could be an issue, it probably was a few years back when I was a noob and didn't know what I was doing...but with the skill I have (and I'm not the most skilled photographer by any means, I am sure I still have many years left of learning just with bird photography, let alone wildlife, landscaps, and all the other things I like to photograph), dynamic range with birds, deer, coyotes, etc. is just never a problem. I control the lighting, as ironic as that may be to say when talking about the sun. I control it because I control the angles involved between subject, photographer, and light source. Get the right angle, and you can reduce dynamic range in the scene to practically nothing (although then your often left with a bland, uninteresting image because it has no contour, so I rarely aim for minimal DR, but I do aim to minimize it so it fits within the capabilities of my hardware), then shooting at high ISO is not a problem.