Upload & Sell: Off
As a user of Sigma lenses (300-800, 120-300, 50-150, 50 1.4 and 30 1.4) I've noticed a common theme. Canon users tend to have more problems with Sigma lenses than Canon users. I suspect that the Sigma lenses just aren't as compatible oh Canon DSLRs. My experience that with Nikon DSLR's, the Sigmas above are extremely sharp and render the out-of-focus areas beautifully, especially at wider apertures.