This ultra-telephoto zoom lens covers a telephoto range up to 500mm and allows photographers to bring the subject close and short perspective. This lens has an equivalent field of view of a 225-750mm when used on digital SLR cameras with an APS-C size image sensor. Sigma’s original OS (Optical Stabilizer) function offers the use of shutter speeds approximately 4 stops slower. As compensation for camera shake is visible in the view finder, the photographer can easily check for accurate focus and ensure there is no subject movement.It is ideal for sports, wildlife and landscape photography with handheld shooting. Three SLD (Special Low Dispersion) glass elements provide excellent correction for chromatic aberration. This lens is equipped with a rear focus system that minimizes fluctuation of aberration caused by focusing. The super multi-layer lens coating reduces flare and ghosting. High image quality is assured throughout the entire zoom range. This lens incorporates HSM (Hyper Sonic Motor), which ensures a quiet and high-speed AF as well as full-time manual focusing capability. The addition of the (optional) 1.4x EX DG APO or 2x EX DG APO Tele Converters produce a 210-700mm F7-9 MF ultra-telephoto zoom lens or a 300-1000mm F10-13 MF ultra-telephoto zoom lens respectively (For Sony fitting only). A removable tripod socket (TS-31) is included as a standard component.

Original of their press release.