0.85x Focal Reducer/Corrector for Sky-Watcher PRO 100 ED APO is designed for serious Astro-Imagers. Optimized for the Sky-Watcher PRO 100 ED APO, this superb quality accessory effectively reduces the telescope’s focal length by a factor of 0.85x and provides much improved field-edge correction.
55mm back focus
M48 threads (not standard T-thread)
Drops ProED 100 from f/9 to f/7.56