10 out of 10 points and recommendedInexpensive, Good Quality BuildNot Constant Aperture
I purchased this lens in September 2007 in a Nikon lens mount version from Amazon. I've used the lens extensively with APS-C cameras (Nikon D90 and D7000) and it performs admirably!reviewed February 19th, 2013 (purchased for $237)
DxOMark recently tested the lens and compared it with a much more expensive Canon EF 16-35mm f/2.8 II USM lens (which costs $1,549.00 at Amazon). The Sigma lens performed very well in the comparison and held its own.
Here's the review and comparison:
The Sigma is a quality lens, made in Japan which won the European Photo & Imaging TIPA Award as the "Best Consumer Lens" in 2004. It's an older but very worthy lens for an FX or DX cameras.