The Askar 91F 0.75x reducer brings the 91F focal ratio down to f/5.2, providing a wider field of view and faster exposure times. This triplet design reducer supports a 44mm full-frame image circle and includes field flattening capabilities, making it ideal for capturing large nebulae, star clusters, and faint, fast-moving celestial objects. Standard 55mm back focus from M48 thread with M59x1 threads on both ends. The included adapter has built-in M48x0.75 2" filter thread.