The Sharpstar f/4.5 Reducer/Flattener for 61EDPH II is dedicated for Sharpstar's 61EDPH and 61EDPH II astrograph refractor telescopes and can also be a replacement reducer/flattener for the one included with the Radian 61 telescope. This reducer/flattener is upgraded from earlier versions and exhibits very little to no chromatic aberration for pristine astrophotography images. At one end of the reducer, there is M63x1 thread, tapped for the connection to the 61EDPH’s reducer and at the other end the reducer, there is M48x0.75 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 the M48 adapter is removed, though this often requires adding extra spacers to your imaging train.
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, which is a perfect focal length for wide-field imaging and beginners. 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.