I need some thoughts here from some of you. It concerns my Canon 100-400 EF lens. As is it well known, this is a lens that it not used most of the time, at least with most photographers. I bought mine in 2009 and and right from the start it was not sharp at all focal lengths but especially at 400mm. And then when brought up to 100% in Photoshop the sharpness really showed it's true colors and was extremely bad. On thing, the quality did not change when used with or without a tripod and with many different camera settings. I sent the lens to Canon for repair and it cam back saying the "focusing ring" was bad. I got the lens back and absolutely not difference in quality. I don't use the lens all the much (it has a special need as you all know) so it was not until this past May that I sent it back to Canon. When I got it back this time a different repair had been done to it and again I had the same results, not sharp.To shorten the story, early Sept it went back with and yet a different repair and when returned, no change. Number four when shipped back to Canon and same story when I got it back. Three of these times I sent with the lens with about 20 plus photos as examples of the poor quality I am getting. I have tried this lens on three different camera bodies, a 40D, 5D and a 7D all with the exact some results, not sharp.Not even close. Now they want me to send in the 7D body in to see what I believe is "telling the truth". All my other Canon lenses and one Sigma are all sharp and pretty much spot on. I have talked with over 16 people at Canon and most have been helpful and a couple of them agree that the lens is bad. But now that it has been "run up the ladder" to higher authority it appears when I send the body in and they find it as they have before, good and to specs, I think I'm screwed. I told the last few reps that I spoke with that if it comes back with the same problem, I am selling it and getting maybe a Sigma. Anyone else have this kind of problem with this lens? Oh, I don't have any images to post, I deleted them all.