Sigma 17-35mm f/2.8-4 EX DG IF HSM Aspherical Super Wide Angle Zoom Lens for Canon SLR Cameras Sigma EX lens with 17-35mm zoom Incorporates aspherical lens elements in the front, as well as rear lens groups Equipped with a silent, responsive and fast Micro Hyper Sonic Motor (HSM) Incorporates internal focusing to prevent deterioration of the optical quality at close distances Use with Canon SLRs that are compatible with AF lenses