APO 200-500mm F2.8 EX DG - SIGMA CORPORATION

APO 200-500mm F2.8 EX DG - SIGMA CORPORATION: "The APO 200-500mm F2.8 EX DG is the world’s first Ultra-Telephoto Zoom Lens that offers a fast aperture of F2.8 at 500mm focal length. It covers the widely used 200 to 500mm focal length range, and maintains its fast F2.8 aperture over the entire zoom range. Four SLD (Special Low Dispersion) glass elements provide excellent correction for all types of aberrations and produce a high level of optical performance throughout the entire zoom range."