NoteWhen using this M42-FD lens adapter, the auto iris, auto focus or other functions will not work properly. Manual AdjustmentThe M42-FD lens adapter is suitable for M42 mounted on FD cameras. Need to manually adjust the aperture of the lens. Narrow Aperture ModeWith this adapter, you need to use "Stop Mode" when metering, because the lens cannot control the aperture by the camera body. Infinity FocusThis camera adapter does not limit the focus and there is no ROM connection on the adapter. DurableThe M42 to FD lens adapter is made of sturdy alloy, no problem for long-term use. If you have any questions about our camera adapter, please contact us in time and we will reply you within 24 hours. Features: Infinity focus, no ROM connection on the adapter. The lens's aperture control is set manually. Automatic aperture, autofocus or any other functions will not work properly when using this adapter. 'Stop-down mode' will need to be used when metering because the lens does not have the ability to control its aperture by the camera body. Made of stable alloy, long-term use is no problem. Specification: Condition: Brand New Material: Plastic, Alloy Color: Black Compatible Camera: For FD Camera (A-1, AE-1 Program, F-1, FTb and others) Compatible Lens: M42 Lenses (For Zeiss, Pentax, Praktica, Mamiya, Zenit) Weight: Approx. 30g Package List: 1 * Lens Adapter