This 3rd party UWA lens awarded as TIPA best consumer lens in Europe 2006. With reasonable price for wide angle lens, Sigma 10-20mm give super wide-angle of view 102.4°to 63.8 for your SLR camera. Sigma 10-20 comes with three pieces of Special Low Dispersion (SLD) elements and three aspherical lens. These three SLD (Special Low Dispersion) glass elements are employed for effective compensation of color aberration, which is a common problem with super-wide angle lenses. One piece of glass mold and two hybrid aspherical lenses, offer excellent correction for distortion, as well as all types of aberration.

Equipped with HSM (Hyper Sonic Motor) system that ensure you a silent and high-speed AF function as well as full-time manual focusing capability for Sigma, Canon, and Nikon-D mount lenses. It also relatively compact, lightweight for an ultra wide-angle zoom lens.

Right now for Nikon mount SLR, this Sigma 10-20mm comes with price of $424.51 while for Canon mount is $427.56. It just slightly different a few bucks. You can check it online now at here for Nikon and here for Canon to get cheap price of Sigma 10-20mm