The world’s first Ultra-Telephoto Zoom Lens that offers a fast aperture of F2.8 at 500mm focal length
The Sigma Corporation is pleased to announce the launch of the new APO 200-500mm F2.8 EX DG Ultra-Telephoto zoom lens. 
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. Shooting distance and focal length can be viewed on the lens’ LCD panel, which is an additional convenience for the photographer. Read the whole article here