The Computer Vet Weblog

Last month I got a new lens for my camera, a Sigma 30mm. But over the last few weeks I was becoming increasingly dissatisfied. I was having problems with sharpness, and just with focus in general. With a narrow depth of field I would use the autofocus to dial in on a subject, but the subject would come out blurry and the focus would be an inch behind it instead. I did some research and found that those Sigma lenses have a history of “backfocusing”, and I got a bum lens.

So I returned the lens, and instead of taking my chances with another Sigma I instead replaced it with a Canon EF 28mm f/1.8 USM. This lens got very good reviews, and was generally considered to be sharper than the Sigma. Plus, you want to use a Canon lens on a Canon body if possible. As you can see from this shot, the autofocus seems to be right on. So maybe I got lucky this time.