Sun 21-Oct-12 10:27 AM | edited Sun 21-Oct-12 10:33 AM by KnightPhoto
I just meant to say that on the assumption that "if things can change over time on a camera" our OP could conduct an AF fine tuning exercise with the camera and some key lenses and see if that corrects the problem. According to Thom Hogan, who does a lot of bumping his cameras around the world, regularly doing so is a way to stay on top of this potential.
Also, that way you get an indication of how far off the camera lens combination is. So if for example +8 corrects it and the issue stays consistent then fine. However, if +20 is not enough to correct the issue, then the camera needs service (or possibly the lens/lenses).
Myself, I tune all my gear when I first acquire it, but I don't often re-do the AF fine tune unless I am seeing something in my images, like the OP has here (which might or might not be more severe than re-tuning can address). Also AF fine tuning can only address a focus problem that is consistent in the first place.
Not sure, is the AF always front-focusing for images coming from the same lens? Also, is there any gunk on your sensor perhaps causing this?