If you have a SLR or DSLR camera and other maker/mount lenses, the Fotodiox Mount Adapters allow you to use your lenses on the film/digital camera body. Sharing lenses has some distinct advantages. Certain prime lens just can't be replaced, and you save the cost of purchase on new lenses. Adapting larger format lens to smaller format sensors (i.e: large format to medium format, medium format to 35mm, 35mm to micro 4/3) provides excellent edge-to-edge sharpness. The smaller image field helps minimize the effects of lens distortion and aberration by using the 'sweet spot' or center of the larger lens image circle.\n\nThis is one of the Fotodiox Pro-series lens mount adapters, made with precision and pristine award standard. As all Pro-series adapters, these adapters have been specially crafted to endure professional lenses. The leaf spring design in the Adapter holds the lens tight to the camera body ensuring there is no play between the camera and the lens. This adapter allows Leica M Lenses to fit on a Sony Alpha NEX E-Mount system camera body.\n\nAlthough the lens will fit physically, automatic diaphragm, auto-focusing, or any other functions will not operate correctly while using this adapter. Please be aware as the Canon EOS lenses have no aperture control on the lens that all shots will be at the minimum aperture (wide-open) for that lens. You can shoot with manual mode or aperture priority mode. Infinity focusing is guaranteed.