Reducer-Flattener from Sky-Watcher that is specifically designed to accompany the Esprit 120 telescope. It has a back focus of 95mm (55mm when back focus spacer and M48 ring are installed). This reducer-flattener reduces exposure time by 68%, compared to the native f/7. The f/ratio drops dramatically from f/7 (840mm) to f/5.4 (647mm). It is equipped with a built-in 2" filter cell to mount your imaging filters. When using a full frame camera, the field of view is 3.18 x 2.12- degrees, and with an APS-C crop sensor camera FoV is 2.08 x 1.39-degrees. This reducer-flattener has a 34mm fully illuminated field, but it can expertly handle full frame as well.