EOS R5 focus puzzle
These three images were hand held, Canon EF 100-400mm f/4.5-5.6L IS II USM + 1.4x".
The focus box displayed in the viewfinder and in DPP does not match the actual focus.
I have included 3 screen captures from DPP.
The camera focused on the first bird to land, but the bird took a drink before I could make a photo and the eye was not visible. In the second and third images, a second bird had landed and the viewfinder and DPP both indicated that the new further bird was in focus, but in fact the nearer bird remained in focus. It is as if the view finder and the AF use different algorithms to determine what is in focus.
Most of the following is from exiftool.
Chipping Sparrow (Spizella passerina) at birdbath
original bird still in focus, but DPP indicates newly arrived bird in focus
original bird still in focus but eye of newly arrived bird detected
You had the SS button halfway pressed in. Focus was locked on the first bird.
Ernie is essentially saying the same thing I just posted. This could be “focus and recompose” at the adjacent AF point level.
Without being to step through the camera executing the firmware in real time, one can only speculate as to what happened. Did the camera ever lock focus on the closer bird?
The camera has more than 1000 AF points, so this image seems highly cropped. AF points are larger than the red box you see in the viewfinder or rear screen.
I suspect what you could be seeing are the AF Case Settings at work. Whatever your current settings, the behavior seems to be “sticky”. It could be that the AF is “sticking” to the previous subject, and has not yet switched to a different subject.
Again, this image seems highly cropped. Where locked AF points are located in the frame when the shutter fires can be misleading. There is always a short time delay between focus lock and shutter firing. It is almost as if the slightest camera shake can “focus and recompose” at the smallest scale.
I would experiment with disabling some of the face, color, and eye tracking settings when subjects are do not fill the frame.
I do not object to the original bird being tracked and staying in focus. I was surprised that the blue box in the viewfinder (red box in DPP screen capture) went to the eye of the newly arrived bird while the original bird was still being tracked and was in focus. I was happy with the focus choices made by the camera but surprised by the focus indicator displayed. Usually when the camera is tracking a bird, the focus indicator stays on the bird that is in focus and being tracked.
These are screen captures from DPP showing the placement of the focus indicator in DPP. In the first image, the original bird is clearly in focus.
In the second and third images, the focus indicator has moved to the newly arrived bird while the original bird is still being tracked and is in focus as expected. The focus indicator does not show what is in focus.