Celestron 0.7x EdgeHD Reducer

0.7x

It shortens focal length by 30 percent, so an EdgeHD 8 goes from 2032 mm to about 1422 mm and frames noticeably more sky. That is often the difference between a galaxy filling the frame awkwardly and sitting in it properly.

f/10 to f/7

Light per pixel scales with the square of the focal ratio, so f/7 collects roughly twice as fast as f/10. An hour of exposure does what two hours did before, which is the main reason imagers buy this.

Matched to EdgeHD optics

It is computed for the EdgeHD's aplanatic design rather than being a generic reducer, so stars stay round to the corners instead of trading coma for field curvature. A generic 0.63x reducer on an EdgeHD gives away much of what the telescope was built for.

Model-specific

There are separate versions for the 8, 9.25 and 11 inch EdgeHD tubes and they are not interchangeable. Confirm your exact model before ordering, and expect to work out the correct sensor spacing during setup.