Sigma APO 50-150mm F2.8 EX DC OS HSM, designed especially for APS-C size image sensors. Sigma’s proprietary OS (Optical Stabilizer) system offers the use of shutter speeds approximately 4 stops slower than would otherwise be possible, enabling hand held tele-photography. Six SLD glass elements compensate for chromatic aberrations and provide high image quality throughout the zoom range. The Super Multi-Layer Coating reduces flare and ghosting and ensures sharp and high contrast images even at the maximum apertures. The lens design adopts an inner focusing and inner zooming system to provide convenient handling and the HSM (Hyper Sonic Motor) ensures quiet and high speed autofocus while allowing full-time manual focus override. This lens has a minimum focusing distance of 80cm (31.5″) and a maximum magnification ratio of 1:6.3. The rounded 9 blade diaphragm creates an attractive blur to the out of focus areas of the image. The addition of Sigma’s TELE CONVERTER 1.4x EX DG APO or 2x EX DG APO produces a 70-210 F4 AF telephoto zoom lens or 100-300 F5.6 AF telephoto zoom respectively.