The sigma 120 300mm f28 dg os hsm lens sigma fit is a telephoto zoom lens that joins sigmas global vision sports line of customisable and fast aperture lenses this dust and splash proof lens is designed to enhance usability and deliver superior optical performance even in the most challenging situations using the sigma usb dock not included available separately users can fine tune and personalise certain functions of the lens to fit their shooting style such as the focus limiter autof