The Askar 0.75X Full-Frame Reducer was designed to shorten the focal length of the 65PHQ to 312 mm (f/4.8). When connected to the 65PHQ, this high quality quaduplet reducer can effectively shorten the exposure time and dramatically increase the field of view, bringing more convenience and possibilities for your deep-sky astrophotography.

The backfocus is the standard 55mm. The 65PHQ Reducer includes an adapter with both M54 and M48 threads.  See the drawing of the adapter for more details.