Celestron 0.7x Edge HD Reducer Lens The EdgeHD .7x Focal Reducer Lens Makes Your EdgeHD 1100 One Full F-Stop Faster Than f/10, Reducing Your Exposure Time by One-Half to Capture the Same Brightness of Object 5-element lens design Maintains similar flat-field performance as native Edge HD optical design Increases Field of View by 43% to Better Capture Wide Field Images Threads Directly onto the 3.25" threads of the EdgeHD which Reduces Mechanical Vignetting and Allows for use with Larger (Full Frame) Sensors and Off-Axis Guiders