I have been trying out three different lenses in the 70-200mm range. Sigma EX 2.8/70-200mm APO Tokina AT-X Pro 2.8/80-200mm SMCP-FA 2.8/80-200mm ED(IF)
All of them seem to suffer from Back Focus. The Sigma not much, though. Had I been offered a used Sigma, I probably would have bought it. I published a small test showing the problem. Due to Back Focus (i BELIEVE), my SMCP F-4-5.6/70-210mm is the sharper one at F. 5.6. Please take a look and feel free to comment: http://www.flickr.com/photos/bladt/sets/1509814/ Regards Jens
