Sigma's 85mm F1.4 EX DG HSM lens is a large aperture medium telephoto lens optimized for use with digital SLR cameras and is especially ideal for portrait and low light photography. Designed with SLD glass and a glass mold element excellent color correction is achieved for all types of aberrations and superior optical performance is ensured. It is equipped with a rear focus system that minimized fluctuation of aberration caused by focusing and the super multi layer coating reduces flare and ghosting even in backlight photography. HSM (Hyper Sonic Motor) ensures quiet and high speed auto-focus capability and the round 9-blade diaphragm creates pleasant out-of-focus highlights.