I was shooting a basketball game last night with my 1d mark lll. It was working fine for the first few shots then I noticed that the autofocus was not working. I have focus tied to the back button. I did not receive an error message and I tried reseating the.lens, mounting a different lens, etc. But nothing helped. Does anyone have any ideas?
Only the standard, try putting the focus back on the shutter button, reset the AF/MF switch on the lens, shut off camera & remove battery, try a different lens to see if it works. What lens was on the body when the AF stopped?
what schlotz said, but if that doesn't work I'd also try clearing all camera settings.
If that doesn't work I'd try to narrow the problem down.
1) Does focus confirmation work in MF? If so your AF sensor is OK.
2) Do other functions work if you set the back button to them? If not it's the button (back buttons aren't as robust as shutter buttons and used constantly like a sport's shooter would they can wear out.)
3) If none of those things identify the problem, it's probably a board gone bad.
By "not working" I assume you mean not attempting to AF at all. If it's trying to AF but not obtaining it, that's different and I'd also try blowing off the AF sensor. Sometimes a piece of dust settles over it and blocks some points.
