The Sigma APO 50-500mm f4-6.3 EX DG HSM Lens for Canon Digital SLR Cameras is a high-magnification zoom lens with a 10x zoom ratio. The advanced optical design of the lens is optimized for digital SLR cameras, and the super coating on each glass surface produces superb color rendition, while reducing flare and ghosting. This lens uses four pieces of Special Low Dispersion (SLD) glass for excellent correction of color aberration throughout the entire zoom range. The Hyper Sonic Motor (HSM) provides quiet high-speed AF function, as well as full-time manual focus capability. 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 50 millimeter focal length, it is remarkably compact and provides easy handling. The tripod mount is composed of magnesium, to minimize total weight. It is also easy to grip and carry the lens due to ergonomic design of the tripod mount. Non-rotating front lens elements, due to the 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.
The Sigma 50-500mm f4-6.3 EX APO RF HSM SLR Camera Lens is a 10x Hyperzoom lens that covers all popular focal lengths from the 50mm "normal" to 500mm ultra-telephoto focal-length perspectives. Designed for a tripod mount, this lens remains lightweight and structurally durable for its size