

I have been happy with the AF on my R5. Speed seems fine, ability to pick up birds is probably limited by the body. I think your R6ii will be fine. The EF 400 DOii works very well with the EF 1.4x iii on my R5, and would be even better on a 24MP camera.I am thinking about picking up one of these lenses for some trips I have scheduled next year. I think the wider aperture will be beneficial for low light situations in jungle and rain forest environments. My biggest concern is AF speed on a Canon R6 Mk2 but I don’t think my RF 200-800 will be very useful on these trips.




As far as we can deduce as users, the Canon AF algorithms are 'open loop', there body doesn't check if something is actually in focus during exposure, it trusts the lens to have moved to the correct position. The obvious example if this is a branch crossing in front of your subject, at the edge of the 'eye box'. The eye will be out of focus, but the branch will be tack sharp.I believe it is. I was testing several modes so I can’t be 100% sure[...]
Presumably, you have downsized the full image to about a 1000 px wide? If so it's difficult to assess critically the sharpness. A crop from the original not downsized would be better.Here are a few more squirrel shots from about 30 feet away. I varied the aperture by one stop but I think they both look fine in terms of sharpness. The cat photo I posted earlier may just be an anomaly related to shallow DOF and camera movement.View attachment 226618View attachment 226619