This ultra telephoto zoom lens covers a range of focal lengths from 50mm to 500mm ultra telephoto. This lens is equipped with Sigma’s unique OS (Optical Stabilizer) function. This system enables hand held photography for many types of subjects such as motor sports, airplanes, close-up and wildlife. Four SLD (Special Low Dispersion) glass elements provide excellent correction of color aberration throughout the entire zoom range. Incorporation of HSM (Hyper Sonic Motor) ensures quiet and high speed AF, while allowing full-time manual focus override.