A Primer on Back Focus in Astronomy
Discuss this article in the AstronomyConnect.com forums
- 1. Overview
- 2. Back Focus of Telescopes and Guide Scopes
- 3. Back Focus of Optical Components for Astrophotography
- 3.1 Required Back Focus of Field Flatteners, Focal Reducers, and Coma Correctors
- 3.2 Working Distance of Focal Reducers
- 3.3 The Back Focus of an Astronomy Camera and Flange Focal Distance
- 4. Understanding Optical Path Length
- 5. Additional Tips
- 6. Examples
- 6.1 William Optics 50mm f/4 ‘RotoLock’ Guidescope
- 6.2 Small Petzval Refractor, DSLR, and a NO Focal Reducer
- 6.3 Small Petzval Refractor, DSLR, and a Focal Reducer
- 6.4 Small Refractor, Astronomy Camera, Focal Reducer, and Filter
- 6.5 Schmidt-Cassegrain Telescopes and f/6.3 Focal Reducer
- 6.6 Celestron RASA Telescope
- 7. Summary