One of the problems is that some people claim a problem (i.e. "doesn't work in AI Servo") but don't really explain what the problem is.
Does it not try to focus at all?
Does it focus and then doesn't refocus?
Does it not focus only when moving between very close and very far away targets (some people mentioned this as the issue)?
Can you check your 7D with this lens in those scenarios to see if it always works? Especially focus on something close (even close to MFD), then, while leaving the AF button pressed, move to a distant target (even close to infinity), then back to close focus. Works just as it is supposed to?
If this works fine, then it is very strange that only some cameras of the same model have an issue with this lens. I guess it's hard to say whether the difference is with the body or the lens. Even if it's something with certain bodies, the lens should still work with them of course...
Hi Clarnibass, The 7D was borrowed from a friend. But I did try all the scenarios you mentioned. And what I found was, the only problem it had, and so does my 60D, is in the close to far and far to close AI servo use. I addressed this in another post here, it may be earlier in the thread, but going from an object say @ 300' and swinging to an object @ 20' I find that it usually will just stop, not even try until you bump the focus again. The same in the opposite direction near to far. If you go in smaller increments say from 20' to 30' to 40' and so on it works just fine and the same in the opposite direction. Does the same on the 60D as the 7D. I did not find this to be a problem, if I'm focused on an object @30' and want to shoot something @ 300' I will just aim and bump the focus button I can't think of a scenario where I would need to track something that would be @ 30' and in an instant be @ 300'. Unless I was attempting to track and arrow in flight or a bullet. But I would never keep them in the sweet spot anyway.