R6 AF problem: camera or user error - how to avoid?

Hi everyone,

recently, I shot a few images with my R6 and the RF70-200/F2.8, and I noticed that although the autofocus works pretty well in most situations, sometimes the focus point is not where I put the focus-box on.

Here are three examples. These are screenshots from DPP4 (50% Zoom), which show the focus area as a red rectangle. But as you can clearly see, the actual focused area is behind or in front of the person/red rectangle.

AF problem, F2.8, 1/5000s, ISO100, 200mm, 50% crop

AF problem, F2.8, 1/4000s, ISO100, 200mm, 50% crop

AF problem, F2.8, 1/5000s, ISO100, 163mm, 50% crop

Hopefully you can help me figure out what was going on there. Maybe I did something wrong and can improve my skills.

It was a backlight-scene, that's why the person is pretty dark. Maybe that was causing the focus-problem, but I guess there should be enough contrast on the person's silhouette to get correct focus. At that time the lens hood was not yet mounted. Would that make a difference for the AF?

Some more details: I used Spot AF and Servo AF (back-button focusing). I was panning slowly from left to right and made 5-6 shots (all having misplaced focus). IS enabled. IS mode 1, although IS mode 2 would have probably been better in that case.
I cannot remember whether the focus was breathing at that moment or not. That would be a possible explanation. But I guess it was not breathing.

Here is another, a little older, example:

AF problem, F4, 1/1000s, ISO100, 200m, 100% crop

As you might guess, in this case, I was not panning the camera And it's not a backlight-scene.

Any thoughts?

Best regards,
da-mkay

This is not uncommon. I get it occasionally with my M6, M6II, and R. The spot AF covers a large enough area that the camera grabs something with higher contrast than your intended subject. I have found that using the smaller spot will often help in these situations, trying to keep the whole spot on the subject (but bear in mind that the actual focus spot isn't exactly the same as what you see in the viewfinder. Also, switching to one shot focus can help sometimes (not an ideal option for a moving subject). Also, switching to face + tracking can help, but it really depends on the subject. The AF systems in these cameras are truly amazing, but they are not fool-proof, and can get fooled occasionally. especially by subjects without a lot of contrast, or set against more contrasty backgrounds.

I imagine the camera figured it was close enough when you clicked the shutter.  The owner wanting the shot to happen when he clicked (for sport moments) versus when the camera had perfect focus.

Servo's problem for me is it driving way off when the focus point is accidentally waved over the background.  It then having to drive all the way back when the subject is back in the AF box.  It not having enough time in a sports moment (ball catch) to get back to the right focus.

Back button focus means Servo is only driving when back button is held?