The Sigma APO 300mm F2.8 EX DG is a high performance telephoto lens and, for the professional photographer, is an absolute requirement. With a fast telephoto lens suitable for capturing the fastest action, whether that is a local soccer game, high school basketball in a dimly lit gym or sports cars racing. This lens also does double duty isolating single faces at a news conference or catching the bride in a candid moment at the wedding reception. Two ELD (Extraordinary Low Dispersion) glass elements provide optimum color correction and sharpness throughout the entire zoom range and a new multi-layer lens coating technology and lens design formula reduce flare & ghosting. Simply adding an APO teleconverter (optional extra), means that this lens can be used as a 420mm F4 AF ultra-telephoto lens with a 1.4X EX teleconverter, or a 600mm F5.6 AF ultra-telephoto lens with a 2X teleconverter. For the professional or advanced amateur looking for such a lens at a value price there is no other choice than the Sigma 300mm F2.8. Equipped with all of the latest technology to compete with the camera manufacturer's products and produces tack sharp end result images.