The Sigma 50mm f/1.4 EX DG HSM Autofocus Lens is a standard lens that provides a large maximum aperture of f/1.4. It is the ideal prime lens for use with all Canon digital or film SLR cameras. When used on Canon digital SLR cameras with the APS-C size sensor, the equivalent focal length of this lens will be 80mm, which makes it an excellent choice as a bright medium telephoto lens. Its large f/1.4 aperture allows for sharply defined contrasty images against a nicely blurred background. The lens offers superior peripheral brightness even at the maximum aperture, and corrects for possible flare. The improved DG lens design corrects for various aberrations. This lens is specially coated to get the best color balance, while cutting down on ghosting caused by reflections from the digital image sensor. The lens provides the utmost correction against lateral chromatic aberration, which is a serious problem for digital SLR cameras.