Camera AFMA changed itself?

[vlad]

After importing photos from this weekend's trip, I saw that quite a few were front-focused. Sure enough, my 5D III was set to -8 AFMA for the camera, and in fact this was shown on the full-info playback if I had been more attentive. The problem is, I didn't set it! I looked back at all the images on the memory card, and saw where I was shooting the same scene with the same lens (100 2.8 macro, no AFMA configured), and in one shot there is no AFMA shown, and then the next shot, taken less than a minute seconds later, it's there and it stays there for subsequent shots.

Interestingly, it seems that although this was a "body" AFMA setting, it's not being shown in playback for all lenses. A lens that had AFMA configured only showed the lens value (I'm not sure how the single AFMA number in playback is determined when there's both body and lens adjustments - does it pick one or do a sum?), and other lenses showed 0. I reset the body adjustment back to 0 but now I'm paranoid that it will happen again.

Has anybody heard or seen this happen?

 

[Atonegro]

Yes, I have seen that before....did cost a lot of pics before I noticed.

The good news is that the newest firmware (1.2.1) solves the problem.

 

[vlad]

Aah this is why I love CR, thank you!

Yeah looking at the fixes in the update:
* Fixes a phenomenon in which the camera changes the AF microadjustment value to -8.

 

[Mt Spokane Photography]

Some have reported it still happening after the firmware update, but it has not happened to me since the update.
You need to keep checking

 

[Loswr]

I'm not sure how the single AFMA number in playback is determined when there's both body and lens adjustments - does it pick one or do a sum?

The AFMA setting has three options, 0: disabled, 1: adjust all lenses (the 'body adjustment'), and 2: adjust by lens. So, the camera will apply whichever is selected.