Sigma 50-500mm f/4-6.3 EX DG HSM APO RF Telephoto Zoom Lens for Olympus and Panasonic SLR Cameras High Magnification Ultra Telephoto Zoom Lens, with a 10x zoom ratio from 50mm to 500mm, optimized for digital SLR cameras. Most effective coating for minimizing flare and ghost with digital SLR cameras. Triple-cam Rear Focusing System ensures high precision throughout the whole focus range. Uses four SLD (the special low dispersion) glass elements for superior optical performance. Accepts both 1.4X and 2X APO EX Tele-Converters, the lens can be used as a 1000mm ultra-telephoto zoom lens.