Hi, I just wanted to know what the back focus is for the Celestron EDGE HD 8" for a ZWO ASI224MC when:
1) When not using a focal reducer; and
2) When using the 0.7x focal reducer
Appreciate your help 🙂
D12108386 If you don't use a reducer, don't have a back focus requirement. If you use a 0.7x reducer, the back focus requirement of it should be 105mm
D12108386 When not using a focal reducer
Since it consists of compound optics, the EdgeHD has an optimal backfocus even when no additional focal reducer is used.
Use the numbers (and spot sizes versus backfocus in graphs) here:
https://www.innovationsforesight.com/support/celestron-edgehd-back-focus-tolerance/
Chen
