Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Chapter 1 Earth and sky
- Chapter 2 Moon and planet observer's hardware
- Chapter 3 The Solar System framed
- Chapter 4 Stacking up the Solar System
- Chapter 5 Our Moon
- Chapter 6 Mercury and Venus
- Chapter 7 Mars
- Chapter 8 Jupiter
- Chapter 9 Saturn, Uranus and Neptune
- Chapter 10 Small worlds
- Chapter 11 Comets
- Chapter 12 Our daytime star
- Appendix 1 Telescope collimation
- Appendix 2 Field-testing a telescope's optics
- Appendix 3 Polar alignment
- Index
Appendix 2 - Field-testing a telescope's optics
Published online by Cambridge University Press: 05 November 2012
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Chapter 1 Earth and sky
- Chapter 2 Moon and planet observer's hardware
- Chapter 3 The Solar System framed
- Chapter 4 Stacking up the Solar System
- Chapter 5 Our Moon
- Chapter 6 Mercury and Venus
- Chapter 7 Mars
- Chapter 8 Jupiter
- Chapter 9 Saturn, Uranus and Neptune
- Chapter 10 Small worlds
- Chapter 11 Comets
- Chapter 12 Our daytime star
- Appendix 1 Telescope collimation
- Appendix 2 Field-testing a telescope's optics
- Appendix 3 Polar alignment
- Index
Summary
The majority of today's amateur astronomers do not make their own telescope optics. Nonetheless, most of us are aware of the basic procedures involved and are familiar with the basic principles of the Foucault and Ronchi grating optical tests. I would, however, wager that very few telescope users realise that simple versions of these tests can be used to evaluate the overall accuracy of both figuring and alignment of the assembled telescope's optics with much greater ease than the toiling mirror maker can assess the individual components in his/her workshop.
The easiest method involves using a Ronchi grating. Many optical firms, especially those dealing in telescope optics and telescope-making materials, sell these gratings. They are very cheap to buy. If a choice is given select a grating of at least four lines per millimetre (100 lines per inch), with more lines per millimetre providing a more sensitive test.
Simply mount a small piece of the grating over the central hole in a dummy eyepiece (a collimation tool described in Appendix 1) and you have all you need to make the evaluation.
- Type
- Chapter
- Information
- Observing the Solar SystemThe Modern Astronomer's Guide, pp. 469 - 472Publisher: Cambridge University PressPrint publication year: 2012