Sigma 412954 20mm F1.4 Art DG HSM Lens for Canon, Black Optical designs is highly resistant to strong incidental light sources such as backlight Minimized Chromatic aberration, distortion, and ghosting. Weight is 2.1 pounds This lens delivers excellent brightness and bokeh and is ideal high speed lens for snapshots. The Sigma 20mm F1.4 DG HSM can be considered as the culmination of the Art line in relation with F1.4 series