Effectively reduce the 400 mm focal length of the Askar FRA400 astrograph to 280 mm by adding the dedicated Askar f/3.9 Reducer to your imaging set-up!  The reduction factor of the full frame FRA400 reducer is 0.7X, and put another way, takes your f/5.6 FRA400 refractor to a fast f/3.9, cutting your exposure times in half!  Telescope side threads are M68x1 and the camera side has M48 x 0.75 threads that accept 2" filters as well as a M48 T-ring or adapter.  Back focus is 55 mm from the M48 thread.