0.85x Focal Reducer/Corrector for Sky-Watcher Evostar 100 ED APO is designed for serious Astro-Imagers. Optimized for the Sky-Watcher Evostar 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. Features:
55mm back focus
M48 threads (not standard T-thread)
Drops Evostar 100 from f/9 to f/7.56
Note: The length of the threads on the reducer/corrector are too long for the ZWO OAGs and cannot be threaded all the way in without changes such as a threaded ring added to consume some of the threads on the reducer, which can affect back focus. Alternately the reducer threads can be machined down.