Have anyone tried setting the DOF button to switch between Ai Servo and One Shot? I aimed at the same spot, but the exposure varied from 1/500s to 1/800s when I switched af-mode. How the hell can that be?
It's not happening 100% of the subjects I shoot at, but 90% and it's 100% consistent at one subject when I push the switch...
I have set the DOF button on my 5DIII in the same way and stumbled across this very issue the other day. However, the exposure only changes when in evaluative metering mode. I have not been able to find the exact answer to why this is, but when googling it, I found that this has also been the case for previous canon models and therefore likely not a problem. It could have something to do with how the camera interprets subject/background differently between the to AF modes when it's set to evaluative metering. I'd appreciate a better explanation as well, but I don't believe it's a problem with our cameras.