The Rokinon Reflex 300mm f/6.3 Ed Umc Cs Lens (Black) is a mirror lens designed specifically for use on Fujifilm x mirrorless cameras. The lens' Cassegrain design enables it to achieve a 450mm 35mm-equivalent focal length perspective within a compact and lightweight lens design that is significantly smaller than a traditional 300mm lens. It features a fixed f/6.3 aperture and utilizes manual focus operation for focusing as closely as 2.95'. One extra-low dispersion element and the inherent mirror construction of the lens work to eliminate chromatic aberrations while providing notable image sharpness and clarity. Furthermore, the Umc (Ultra Multi Coated) coating has been applied to reduce surface reflections, lens flare and ghosting while also contributing to improved overall contrast..