EOS R6 - AF not on target on few pictures

Chris_From_Holland wrote:

Karl_Guttag wrote:

It might help to post a few pictures (preferably full-frame and resolution). Sometimes people think they have one problem when it turns out to be something different. Without a picture is it hard to know

Were you using the shutter button half-press focusing or using the back button focus? Sounds like half-press but just wanted to check.

Any chance the camera moving between focus locking and the shot? Not saying you did but it seems strange the focus lock point was not in focus.

Chris_From_Holland wrote:

Hello,

I'm going through my yesterday concert shots, and I have a bunch of pictures where the AF seems to be way off.

As the lighting was limited and very red (hence high ISO), I'm wondering whether it's simply me hitting the limit of the AF tracking, or if I have to worry further.

EOS R6 + Canon RF 70-200 f/2.8 (Raw only)

Camera set in Fv mode, shutter 1/200, Aperture f/2.8, ISO 8000

AF mode : Face/Eye detection + tracking (priority People)

Servo AF Mode 4 (sensitivity -1, accel +1)

The AF-Point is set on the face (eyes were not detected) and confirmed locked on the face (DPP confirms the red square), but the face is not sharp while the cymbal ~1m in front of the drummer in crisp sharp.

I have this problem on few pictures, and the AF is again spot on the next pictures (face sharp, cymbal not).

I'd lean towards a case of bad luck, but I kindda need to understand to avoid same problem next time

Thanks!

Chris

I can make the raw available on demand, but not widely, as I don't want to breach privacy,
I was indeed using the Back-Button focus, and it might have been moving unknowingly. What puzzles me is the fact that the AF is reported locked

Understand that posting a picture can be a problem.

I'm still not 100% sure what focus mode you are using. Is say AF-On (only) set to AF-Face-Eye?  As another poster pointed out, In servo mode, the shutter will release without the focus being locked on what you want. BUT, you should not get a red focus square on review if the focus was not actively locked at the instant of shooting.

I'm baffled that the RED square appeared in DPP4 if the focus was not locked on that point. As I understand it (and based on some tests), the square means that it actively focused when the shutter went off. Let's say you locked focus, but then your finger came off the back button just before you shot; there should not be one or more RED squares. The same goes for recomposing with a single AF point (you will get a black square but no RED square if the camera is not actively focusing when the picture is shot.

Due to the red square, it seems like the camera thought the AF was locked. Maybe it locked badly on the face in the bad light.

My default AF setup is with two back button focus buttons. With the focus mode set to AI-Servo and a single point focus. The * button is set to eye detect focus (and then moved the AE lock to the AF Point Select button).  In this way, I can go with either method based on which button I press. If the eye detection is having a problem (not locking or jumping around), I can quickly to a point focus with the joystick or focus and recompose.