Sigma Zoom Normal-Telephoto 50-500mm f/4-6.3 EX APO DG HSM Autofocus Lens for Nikon AF-D

High Magnification Ultra Telephoto Zoom Lens, with a 10x zoom ratio from 50mm to 500mm, optimized for digital SLR cameras.This high zoom ratio lens is optimized for digital SLR cameras and capable of covering a wide range of focal lengths from 50mm standard to 500mm ultra telephoto. Reduction of Flare and Ghosting The advanced optical design is optimized for digital SLR cameras. In addition, the new super coating on each glass surface produces superb color rendition, while reducing flare and ghosting. SLD glass for superior optical performance This lens uses four pieces of SLD (the special low dispersion) glass for excellent correction of color aberration throughout the entire zoom range. HSM (Hyper Sonic Motor) The HSM models (the HSM is only available for AF Canon, Nikon and Sigma Mounts) provide quiet high-speed AF function, as well as full time manual focus capability. APO Tele-Converter EX (optional) By adding an APO teleconverter (sold separately), you can use this lens as a 140-700mm F7.3-8.8 MF ultra-telephoto zoom lens with a 1.4X EX teleconverter, or as a 200-1000mm F10.4-12.6 MF ultra-telephoto zoom lens with a 2X teleconverter.(Teleconverters can be used in 100mm 500mm focal length range) Easy Operation and Handling This lens also features a Zoom Lock device to eliminate Zoom Creep when the lens is tilted down. When the lens is set to the 50mm focal length, it is remarkably compact and provides easy handling. The tripod mount is composed of magnesium, to minimize total weight and also it is easy to grip and carry the lens due to ergonomic design of the tripod mount.Non-rotating front lens elements, due to rear focus mechanism make possible the use of a custom bayonet Petal-type Hood, which prevents extraneous light from degrading the image quality. This mechanism also allows the use of circular polarizing filters, since the front barrel does not rotate during focusing or zooming.&ref=Become