The Sigma 70-210mm f4-5.6 lens is a telephoto zoom lens with a focal length range of 70-210mm and a variable aperture of f4-5.6. It features a minimum focusing distance of 1.5m and a maximum magnification ratio of 1:4.2. The lens is designed for Canon EF, Nikon F, and Sigma SA mounts, and is compatible with full-frame and APS-C sensor cameras.