Focal Reducers for Astronomy
Figure 1 – Focal reducers of various designs and manufacturers. Image credit and copyright Agena AstroProducts.
- 1. Introduction
- 2. How Focal Reducers Work
- 2.1 Some Basic Definitions
- 2.2 Using a Focal Reducer at the Working Distance
- 2.3 Adjusting the Reduction Factor of a Focal Reducer
- 3.Types of Focal Reducers
- 3.1 Overview
- 3.2 Focal Reducers for Refractors
- 3.3 Focal Reducers for Compound Telescopes
- 3.4 Focal Reducers for Newtonians
- 3.5 Focal Reducers for Ritchey-Chretien and Field Flattened Scopes
- 3.6 Focal Reducers in 1.25" and 2" Barrel Formats
- 4. Practical Considerations of Focal Reducers
- 4.1 Field of View and Image Circle
- 4.2 Back Focus Requirements of Focal Reducers
- 4.3 In-Focus Travel
- 5. Summary
- 6. References
- Appendix