This large aperture telephoto zoom lens, incorporating Sigma's original Optical Stabilizer function, covers focal lengths from 70mm to 200mm and offers a constant aperture of F2.8 over the entire zoom range. The OS function offers the use of shutter speeds approximately 4 stops slower than would otherwise be possible. It makes shooting easy for many types of photography such as portraits and sports. Two FLD ("F" Low Dispersion) glass elements, which have performance equal to fluorite glass, and three SLD (Special Low Dispersion) glass elements provide excellent correction of color aberration. Super Multi-Layer Coating reduces flare and ghosting. The lens incorporates HSM (Hyper Sonic Motor), ensuring a quiet and high speed AF as well as full-time manual focus capability. It is also possible to attach Sigma's optional APO Tele Converters.