I noticed when assembling a panorama taken with my 17-55mm, that the right side of the image is unusably soft at f2.8. I did some test images today mounted on a tripod with remote release, confirming my concerns. I'm attaching the full image of the test and a crop from the midline to where it softens. Is this the kind of performance others are getting or should I send it back? The left side seems okay. (This lens has been babied my me since I purchased it, BTW). I also repeated the test with my 18-70 and the cheapo kit lens did much better (of course that was at 18mm and f3.5, as opposed to 17mm and f 2.8).