Evostar 72ED Reducer/Flattener (.85x)

Compatible with both APS-C and full frame sensors, APS-C (crop sensors) and smaller recommended 55mm back focus Drops f/ratio from native f/5.8 (420mm) to f/4.93 (355mm) Reduces exposure time by 38% compared to native f/5.8 5.8 x 3.87-degree field of view when used with a full frame camera 3.79 x 2.53-degree field of view when used with APS-C crop sensor  Includes thread-on adapter to mount reducer to Evostar 72ED focuser