The field flattener & reducer for the ASKAR FRA 400 is a dedicated corrector with a reducing power of 0.7X. It shorten the focal length from 400mm to 280mm and the focal ratio from f/5.6 to f/3.9 halving the exposure time. The working distance between the flattener and the sensor is 55mm.
The flattener/reducer can be connected to the focuser of the Askar FRA 400 using the M62x1 male thread, on the camera side there is the universal M48x0.75 male thread. The flattener has an internal M48 x 0.75 thread to accept any standard 2" filter.
Spot diagram SharpStar 400 + 0.7x dedicated reducer