I got the 7D when it was first released and was one of the unlucky ones who had MAJOR AF problems with that camera.
CSC tried to calibrate the camera but I am not sure how thorough they were. The entire calibration procedure can take DAYS especially when multiple zoom lenses are involved as
outlined here. They usually try to cut corners and that
link I just provided explains why.
Anyway, I finally gave up on the whole CSC calibration thing after going back and forth 5 times for more than a month. I asked for a replacement and CSC graciously acquiesced to my request. The replacement is from the latest batch of 7D from Japan.
I can confirm AF of the replacement is a drastic improvement from my original copy.
Sensor performs slightly better at low ISO and slightly poorer at very high ISO (6400 etc), as compared to my first copy. Couldn't be happier. :bsmilie: It is also free from low ISO banding (
see here for example).
AF is NOT perfect though as compared to my el cheapo 450D: area AF for flat distant subject is iffy. Also, there is also some slight non-linearity in the 'gain' adjustment wrt subject distance (slightly back-focus near minimum focusing distance)... but MUCH better than my original copy after CSC calibration. Also, 'gain' adjustment wrt to different focal lengths in my zoom lenses works VERY well, so any micro-adjustment setting at the tele end works just as well at the wide end.
The last point is an indication of a relatively well calibrated AF sensor (see
here for details) since my primary zoom lens was perfectly calibrated to my 450D body.
If you plan to only use ONE camera body and multiple lenses, I strongly recommend you bring ALL your lenses to CSC and request for them to be calibrated for that one body. Seems like CSC does much better when they adjust lenses to body than vice versa. The fact that lenses need to be perfectly matched to EACH camera body is also discussed in detail at
this website maintained by a lens rental shop. Since I am holding on to two camera bodies (one with and one without AF adjustment), I am willing to make some sacrifices.
Serial number of replacement is 0430xxxxxx. The serial numbers of early batches start with 02... I understand that even some cameras with serial numbers starting with 03... are problematic as experienced by
another unfortunate owner here. In short, avoid cameras with early serial numbers: they either have problematic imaging or AF sensors.
