The 2x Converter from Samyang effectively doubles the focal length of whatever lens it is used with. It can be used on any lens equipped with a T-mount or T-mount adapter. Samyang converters use high quality glass with anti-reflective coatings. The converter can also be used for telescopes that have the T-mount system.
Note: As with any tele converter there is a loss of light, for 2x converters this is approximately of 2 EV stops.