Am I about right here or missing something
600f4 mkII 1dxmkII = 21mp
400f4 DO mkII 5dsr = 50mp the image will be around 33% smaller but that still leaves 33mp making the image about 34% bigger than the 1dxmkII 600 combo
This is for Mps on the bird if taken from the same position
Have I got this about right ?
I think the area of the sensor occupied by the bird will be 2.25x larger using the 600 (= 600/400^2).
Also bear in mind that if you crop on the 5DSR then you lose the light-gathering advantage of the full-frame sensor so you'd be looking at 7D2 levels of noise, etc.