I am currently in the process of having my 50D/24-70L recalibrated by Canon. Bought it at B and H, took it with me on a 5-week trip to shoot related to my work (art historian), then found in the field that it was soft. I could sharpen in post-shoot well enough for a Powerpoint presentation; but shots did not come out of the camera at the sharpness one expects from such a rig. In fact, for architectural detail and texture of, say, stone or glass, sharpness is important.
Sent it off once to Canon and came back with explanation for 50D, "it was found that the part was out of position the focus did not operate properly. Adjusted exposure & f/b focus w/ lens, cleaned C-MOS and checked all factory specs." And for lens, "it was found that the part was out of position the focus did not operate properly. Replaced collars. Adjusted center/tilt/focus w/body, cleaned factory specs."
It still does not focus sharply, seems somewhat erratic, short and long focal lengths, near and distant subjects, F2.8-8.0, indoors and out, with or without tripod, always shooting fast enough to prevent shake.
It is now back with Canon Factory Service in NJ.
Can anyone with experience with Canon Factory Service advise me about next steps if it still does not focus satisfactorily?
P.S. I am happy to hear of people whose equipment works, and I am indifferent to posts about technique versus equipment. But if neither is your thing and you have something substantive to advise about dealing with Canon on this sort of issue, please do not hesitate to send me a private message, and know that it will be much appreciated.