ZWO 0.75x Reducer for 65mm Quad APOZWO has released a brand new FF65APO 0. 75 full frame reducer with a four element optical design. It has a reduction factor of 0. 75x, which gives the FF65APO f 6. 4 astrograph a shortened focal ratio of f 4. 8 and a shorter focal length of 312mm. This allows for less total integration time and a wider field of view, bringing more convenience and possibilities for your wide field deep sky imaging. The back focus distance is the standard 55mm. It also