The adapter is built with multi-coated optical glass. The lens fits physically, automatic diaphragm, auto focusing, or any other functions will not operate correctly. 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. Use the lens in the fully manual exposure mode (M) or set your camera to Aperture Priority (AV) mode to use the camera in auto exposure. Preserve all focusing range up to the infinity point.