The 2.3″ 61EDPH f/4.5 full-frame reducer is dedicated for Sharpstar 61EDPH and 61EDPH II astrographs. At one end of the reducer, there is M63×1 thread, tapped for the connection to the 61EDPH’s reducer and at the other end the reducer, there is M48×0.75 thread for the connection of most stock cameras. The back focus is 55mm after the attachment of a camera.The maximum back focus can be extended up to 99mm if users add extra spacers(not included).
The reducer is designed with a three-element air-spaced lens structure, supporting full-frame imaging, effectively controlling unwanted vignette. The practical focal ratio of the Sharpstar 61EDPH when used with this reducer is f/4.5, and the focal length can be shortened to 275mm. It’s preferred by many deep-sky astrophotographers.
Another improvement is that the f/4.5 reducer is also designed with a 360-degree rotator, which is of great convenience for composition when imaging the deep-sky objects.