Leica APO-Extender-R 2x Tele-Converter

The dedicated Leica 2x APO Extender-R (also known as a teleconverter) will multiply the focal length of the existing lens by 2x, and will cut back the amount of light by 2 f/stops. For example, using a 2x teleconverter with the 280mm f/2.8 APO lens will effectively increase the focal length to 400mm. A lens set to f/2.8 will now be f/5.6