Reducer Lens .7X - EdgeHD 800The EdgeHD . 7x Focal Reducer Lens makes your EdgeHD 800 one full f stop faster than f 10, doubling the equivalent exposure at f 10 4 element lens design Maintains similar flat field performance as native EdgeHD optical design Increases field of view by 43% (double by area) to better capture wide field images Optimized for APS C sized sensors, including most DSLR cameras and Nightscape CCD cameras Provides generous 105 mm back focus to accomodate