The Sigma 70-200 2.8 EX DG HSM OS is a large aperture telephoto zoom lens which features Sigma technology including a Hyper Sonic Motor (HSM) and an Optical Stabilizer (OS). Fast, sharp and highly versatile, the 70-200mm 2.8 is a staple focal length for many types of photography including wedding photography, portrait photography, sports photography, and wildlife photography to name a few. Two FLD glass elements (with performance equal to Flourite) and 3 SLD elements (Special Low Dispersion) ensure outstanding image quality through the entire 70mm to 200mm range. An OS system compensates for camera shake when shooting handheld and a rounded 9 blade diaphragm creates beautiful bokeh. Designed for full frame cameras, the 70-200mm 2.8 will work on APS-C sensors, translating to roughly 112-320mm.