Humm..well, I tried it on two of the same bodies, one was a little better than the other but nothing to brag about. Neither of them was as bad as the examples I posted. I went outside and took the same picture with both T5i's and one was as fuzzy as the one posted and the other was clearer and not as bad. So getting mixed results. I tried back button focusing and shutter focusing - One shot focusing mode. Focusing on the same subject, same eye, same exposure and yet one is better than the other. Could it now be a camera thing. The T5i's do not have micro adjustment. Canon's paperwork said they replaced 3 internal collars.
please don't use AF. test manual focus. that eliminates the AF possibility.
as for replacing collars--if Canon stated that then they indeed did find something physically wrong. Canon doesn't replace stuff unless it's a last resort. typically they will send back with a notice saying something like, "carried out adjustments to the AF assembly" (which I've been told is a catch-all statement and you can't draw conclusions on whether they touched the glass or just reprogrammed) or some variance of that. then if you push they do more specific tests and finally come back with "replaced ___." so if they say they replaced something, you can be pretty sure it was broke. BUT, that doesn't mean it's not a combination of both physical and AF problems.
in fact, almost all lenses/bodies require some AF adjustment. so, if your camera doesn't have adjustment you pretty much will never get the most out of most of your lenses unless you also send your body in to Canon for adjustment, and even then it's only adjusted to Canon's reference. so if you get a new lens, you'd also need to send that lens in to be adjusted to their reference.
