Kipon Leica L39 Mount Lens to Leica M Body Mount Adapter allows you to attach Leica L39 Mount Lens to a Leica M Digital or Film Camera Body. This adapter gives you the advantage to still be able to share your lenses between cameras without having to spend more on a whole new lens. Certain lenses cannot be replaced and maybe you like the look of a certain lens but want to be able to use it on another type of camera body. Now You Can!Although the lens will fit physically, automatic diaphragm, auto-focusing, or any other functions will not operate correctly while using this adapter. "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. You can shoot with manual mode or aperture priority mode.