I've seen a number of comments in various threads about people getting stuck with 'bad' lenses that they end up having to send in to Canon for repairs, adjustments or replacement. Does Canon charge you if the lens needs an adjustment because it wasn't properly set up in the first place? Is there a quick and easy way to test the lens in the camera store to rule out most problems or will the clerk perform any tests at the time of purchase. I was thinking it might be beneficial for everybody if there was some kind of testing unit in the camera store that would test the lens's focusing, etc. I wouldn't even mind paying $5 to have the lens tested as opposed to having send into the manufacturer.