Ryan McGinnis
EF5
Just thought I'd give a heads up on my experience with this lens. I picked one up because I really, really miss true superwide photography -- and it's quite difficult to get true superwide on a 1.6X crop camera like the 20D. In comes Sigma with their 10-20mm f/4-5.6 EX. Sigma catches a lot of crap for not being OEM, but they're capable of creating some quite capable lenses.. their 70-200 f/2.8 is excellent, as is (I hear) the new 100-300 f/4.
However, this lens, the 10-20, was a dud for me. It turned out to be quite clearly defective, with severe centering problems that caused objects in the righthand side of the frame to be soft... very, very soft. (The left side of the frame was quite nice and very, very crisp, leading me to believe that if you get a good copy of this lens, you'll be very happy.) This is a QC problem, as far as I'm concerned, as a lens producing such a flawed image never should have made it past the end of the assembly line. A little Googling reveals that this is actually not an isolated problem -- several other reviewers had the exact same problem that I did! Thus, I'm returning it and purchasing the Canon 10-22 3.5-4.5 instead. If there is one thing that Canon can be relied upon for, it's reliable QC. Well, that and inflated prices. But storm season is upon me and I don't have time to screw around playing the game of lens-swap.
So my advice on this lens would be to avoid it, or at least know that you're taking a risk that you'll get a defective lens if you do.
However, this lens, the 10-20, was a dud for me. It turned out to be quite clearly defective, with severe centering problems that caused objects in the righthand side of the frame to be soft... very, very soft. (The left side of the frame was quite nice and very, very crisp, leading me to believe that if you get a good copy of this lens, you'll be very happy.) This is a QC problem, as far as I'm concerned, as a lens producing such a flawed image never should have made it past the end of the assembly line. A little Googling reveals that this is actually not an isolated problem -- several other reviewers had the exact same problem that I did! Thus, I'm returning it and purchasing the Canon 10-22 3.5-4.5 instead. If there is one thing that Canon can be relied upon for, it's reliable QC. Well, that and inflated prices. But storm season is upon me and I don't have time to screw around playing the game of lens-swap.
So my advice on this lens would be to avoid it, or at least know that you're taking a risk that you'll get a defective lens if you do.