Hi Alan, dug up a picture I shot a year ago; same tree - same species of woodpeckerNice shot. At 12m, I would have used the bare 100-400mm II and f.5.6 at a higher shutter speed. It’s not generally appreciated that there is variation between TCs and how they pair with different lenses. Over the years I have 3 1.4xTC IIIs and 3 100-400mm IIs. My newest TC pairs beautifully with one of the zooms and is reserved for that whereas it is significantly worse on the other zoom.. luckily my other TC is the best one for the prime. Both TCs are sharp across the frame. The third was soft at the edges.
There is, of course, more detail from the 600mm lens, especially as it was used at less than half the the punishing iso of 3200 for the Canon lens. As I wrote earlier, I would have used the 100-400mm at f/5.6. And that was the point, using it wide open so as it to lessen the iso required in low light. By using it at f/7.1, you have taken it above the DLA, and have raised the iso 2/3rds of a stop. Also, by choosing 1/640s rather than 1/200s for the Sigma, you have raised the iso by another 1 2/3rds stops. I always tried to keep the iso of the 7DII to 800 or less for static shots because the noise starts to lower resolution above about 640.Hi Alan, dug up a picture I shot a year ago; same tree - same species of woodpecker
Portrait shot is 100-400 II at 400mm, f/7.1, 1/640s, ISO3200 (slightly cropped)
Landscape shot is 60-600mm at 600mm, f/6.3, 1/200s, ISO1250 (full image)
Both on 7DII
Below I took 1200x1200 pixel cut-outs around the birds head; so as equal as possible comparison (i.e. 1200 sensor pixels each)
and the 60-600mm:
I think you'll agree that there is more detail in the 600mm shot.
Sure the ISO3200 does not help sharpness on a 7DII but nonetheless...
This one photo brings back the fond memories of Moosejaw and my brand new Ftb, purchased at the brand new Walmart??, more than all the others. Love it.