I thought I'd give the RF 800mm f/11 a whirl on the R6 because it should give the same resolution as the RF 100-500mm on the R5 and the large pixels on the the R6 would not be affected so much by the f/11 diffraction. I thought the high iso performance would be good, but I was bowled over. I was set up for BIF at 1/3200s and suddenly a small bird dropped by for a second, some 15m away in the shade. This is an 800x800 pixel crop from the centre at iso 20,000 of a Whitethroat.
View attachment 204442
...there is so much to unpack in your wonderful posts in this thread and
here.
It would be interesting to see your real-world comparisons (bird images!?) of photos obtained using the R5 (smaller pixels) & the R6 (larger pixels) with the f/11 800 lens...looking for observable diffraction effects on image quality. Your posts here and elsewhere helped catalyze my own efforts on this topic and (at times) I'm not certain what I actually observed! In my studies, simple hand-held shots (various apertures) of our moon in its various phases are as (reproducibly) revealing of the effects of diffraction as anything, in what are essentially gray-scale images.
In a more recent post, you referenced how some noise-reduction software had improved the high-ISO image
above.
I would very much like to see the 'original' jpeg...prior to the application of noise reduction strategies