The physical design utilizes Thermally Stable Composite material for durability in a wide range of environments, and a brass bayonet mount also offers rigidity and mounting precision. the prime telephoto lens is designed for full-frame Canon EF-mount DSLRs, however, can also be used on APS-C models where it will provide a 216mm equivalent focal length. A prime telephoto lens is designed for full-frame Canon EF-mount DSLRs, however, it can also be used on APS-C models where it will provide a 216mm equivalent focal length. Two F Low Dispersion (FLD) and two Special Low Dispersion (SLD) elements are featured in the optical design and help to reduce color fringing and chromatic aberrations for improved clarity and color accuracy. Nine-blade rounded diaphragm contributes to a smooth and pleasing bokeh quality. The bayonet mount is constructed from brass for ensured accuracy and durability. Additionally, rubber sealing is incorporated in the mount design to render it dust- and splash-resistant.

Sigma 135mm F/1.8 DG HSM Art Lens Specs..