This Sigma 50-500mm f/4.0-6.3 EX DG is an ultra superzoom lens that encompasses all popular focal lengths from the 50mm normal to 500mm ultra-telephoto; a 10:1 zoom ratio which provides tremendous versatility.
The use of an apochromatic design, four elements of SLD (Special Low Dispersion) glass & a seven group zoom system of multicoated optics enables this lens to provide a high level of performance as well as versatility. A rear focus system insures quick, convenient manual focus and a non-rotating front barrel.
The improved DG lens design corrects for various aberrations. This lens is specially coated to get the best color balance whilst cutting down on ghosting caused by reflections from the digital image sensor. The lens provides the utmost correction against lateral chromatic aberration which is a serious problem for digital SLR cameras.
By adding the optional Sigma APO teleconverter, you can use this lens as a 70-700mm f/7.3-8.8 Manual Focus ultra-telephoto zoom lens with a 1.4x EX teleconverter, or as a 100-1000mm f/10.4-12.6 MF ultra-telephoto zoom lens with a 2x teleconverter. Teleconverters can be used in 100mm - 500mm focal length range.