Sigma DG 15-30mm f/3.5-4.5 EX Aspherical

fabulous! Great lens, my usage is only for video - so I'm not to worried about total sharpness into the 4 corners , with aperture fully open.

Great wide angle lens This is one of the sharpest lenses I've used. Great contrast, excellent edge sharpness, both on APS-C and full frame. The one downfall of this lens is the focus drive. It's fairly loud, and slower than Canon USM or Nikon SW systems, but if you shoot wide angle, you're most likely not concerned with that. Sharpness is very close, if not better than the Canon 17-40mm f/4 L. Filter attachment is a little weird with the "filter hood" that goes over the built in hood. I've also had the lens show light flares, but good practice makes this avoidable. Overall, and excellent value for a sharp wide angle lens. The few drawbacks don't take away from the sharpness or build quality.

Sigma 15-30mm f/3.5-4.5 EX Aspherical DG - Nikon This review is based on sample of one in late 2010. I have been an avid photographer on film and digital, but not a pixel peeper; for the amount paid, this lens is more than I expected. Good: super-wide FX on Nikon D700. Great details on center and some corners. Color rendition is fine. Bad: Not able to get sharp results on one corner at infinity focus, doesn't matter what the setting is. Sigma quality control issues are well known, lens possibly de-centered. I decided to keep this purchase for interior and architecture shots where close in and medium distance renditions are important. There are not too many economical alternatives any way.