Comments about Sigma Sigma 18mm - 50mm f/2.8 EX DC Autofocus Zoom Lens for Canon EOS Digital SLR Cameras:
I've gotten two of these. The first jammed up when zooming on the first day I got it. The focus mechanism couldn't get to anything farther than 6 feet away. I thought it was a manufacturer's defect so I returned it and got another. My new lens doesn't jam but the highlights flare, it's not so sharp, and the autofocus likes to find it's mark then recoil just enough to leave you subject annoyingly blurred. Find another lens unless you're on a tight budget and just have to have this range/are willing to risk poor image quality. Not for a pro.