I have had this lens for while now, but never quite satisfied with its sharpness. So recently I did some tests and compared shots with a friend who also has a the same lens. (I'm using a 7d, he has a t1i). The test subject is a paper with 1" squares, with the center square having more lines for detail.
The 1st pic here is a 1:1 crop showing the single AF point.
(AE mode, 4.0, 1/2500, 200mm focal length, standard pic style, sharpness 3, used tripod & 2sec timer)
The 2nd pic was taken by my buddy with his lens & body:
(AE mode, 4.0, 1/3200, 200mm f. len, stand pic style, handheld, oneshot)
You can see that there is a huge difference in sharpness. I've tried the micro-adjustment on the 7d, but cannot get it any sharper.
From what I've read here & else where this lens is highly recommended, and one of its best assets is it's sharpness. But mine sure is not. Any recommendations are appreciated.