The 2.5" 94EDPH f/4.4 full-frame reducer is dedicated for Sharpstar 94EDPH astrograph. At one end of the reducer, there is M74×1 thread, tapped for the connection to the 94EDPH’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 reducer is designed with a four-element air-spaced lens structure, supporting full-frame imaging and the image circle reaches 50mm, effectively controlling unwanted vignette. The practical focal ratio of the Sharpstar 94EDPH when used with this reducer is f/4.4, and the focal length can be shortened to 414mm. It’s preferred by many deep-sky astrophotographers.
Another improvement is that the f/4.4 reducer is also designed with a 360-degree rotator, which is of great convenience for composition when imaging the deep-sky objects. The above-mentioned M48 thread is suitable for the connection for standard 2" filters.