The M42x1 Lens to Leica M Body Lens Mount Adapter from NOVOFLEX allows a M42x1 lens to be mounted to a Leica M mirrorless camera. Although the lens will fit physically, automatic diaphragm (AE metering), or any other functions are not retained using this adapter. In this case you will need to meter in "stop-down mode" since the lens does not have the ability to have its aperture controlled by the camera body. No rangefinder coupling! Please use a Leica M-camera with Live View-Mode.