Canon 5d mkIV vs Sony A7R III vs Nikon D850

[tron]

Interesting! Just 20 days ago I encountered some cases where I could not focus at small birds with my 5DsR and 400 DOII. Also I has encountered a case 13 months ago with 5DsR and 500mm f/4. In the latter case the bird was in the shadows and I was shooting almost against the sun. But not in the first case. Annoyed this year I changed AF servo settings to balance shutter release with af and turned the af ring manually! In fact I used kind of focus stacking since being short sighted I could not be 100% sure about my manual focusing. True these were rare cases but still annoying.

 

[Talys]

Returned this morning from New Zealand. Our guide in one of the reserves had a D850 and a Nikkor 400mm/2.8. He had great difficulty focussing on small birds in darkish foliage close by whereas my wife with a 100-400mm II on a 5DSR at f/5.6 and I with a 400mm DO II on a 5DIV at f/4 had no difficulties. This is just a one-off report, but it goes to show that there is more to AF than nominal sensitivity in ev at the centre or the ability to track.

Interesting insights. Thanks sharing!