Hi all. First time poster to the site and just recently found it about a month ago.
I shoot with a 7D and mainly the Tamron 17-50 2.8 and a few others including a Sigma 300 2.8 non IS.
Recently I was having major problems with my 7D and focusing. I was never able to get faces/eyes in focus. After much reading (mostly on this site) I came to the conclusion to first try a hard reset on the camera.
I am happy to say that this was all that I needed to do and it is now focusing like a charm (again).
What causes a camera to loose "focusability" of that is even a word over time? None of my other cameras have done this (rebel, 1D Mark II).
Anyways, if you have this type of problem I urge you to at least try the hard reset first to see if it helps. Again, thanks to all on the site who have suggested this in the past.
I have attached a pic I got today that never would of been possible had I not tried suggestions.