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. Fotodiox offers a range of adapter from large format to smaller format digital adapters. 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.This adapter gives you the ability to use your irreplaceable prime lens with your new camera and saves you the cost of purchasing new lenses. Fotodiox 'Pro' Series adapters are made with precision and pristine award standards to insure the perfect fit for your camera and lens and to endure professional use. The unique styling maintains/enhances professional appearance. This adapter allows Contax 645 (C645) mount lenses to fit on MFT (Micro-4/3, M4/3) Mount Mirrorless Cameras.Automatic diaphragm, auto-focusing, and other functions will not operate correctly while using this adapter as it is not electronic. In this case, "stop-down mode" will need to be used when metering since the lens does not have the ability to have its aperture controlled by the camera body. Infinity focusing is guaranteed.Included:Fotodiox Pro Contax 645 (C645) Lens to Canon EOS (EF, EF-S) Camera Body AdapterFotodiox Canon EOS (EF, EF-S) Lens to MFT (Micro-4/3, M4/3) Mount Mirrorless Camera Body AdapterPlease note, the product pictured may have slight differences in appearance from the actual product such as color, font style, and/or other cosmetic changes due to improvements in design.