Blending a long reach with a convenient form factor, the Canon EF-mount 100-400mm f/5-6.3 DG OS HSM Lens is a telephoto zoom within Sigma's Contemporary series that blends both a refined optical design with a compact and lightweight physical construction. On the optical front, this zoom utilizes four SLD glass elements to noticeably reduce chromatic aberrations and color fringing throughout the zoom range for improved clarity and color accuracy, and a Super Multi-Layer Coating has also been applied to increase contrast when working in strong lighting conditions.Balancing the optics, the lens sports a Hyper Sonic Motor to produce quick, smooth, and quiet autofocus performance with full-time manual focus override. An Optical Stabilizer also benefits handheld shooting by minimizing the appearance of camera shake for sharper imagery. The physical design utilizes Thermally Stable Composite material for durability in a wide range of environments; both twist and push-pull zoom mechanisms are available for improved control over field of view; and a brass bayonet mount also offers rigidity and mounting precision.