Book contents
- Frontmatter
- Dedication
- Contents
- Preface
- Acknowledgements
- Prologue A Tale of Two Scopes
- 1 Telescope and Observing Fundamentals
- 2 Refractors
- 3 Binoculars and Spotting Scopes
- 4 The Newtonian Telescope and Its Derivatives
- 5 The Cassegrain Telescope and Its Derivatives
- 6 Telescope Maintenance, Collimation and Star Testing
- 7 Telescope Accessories
- 8 Telescope Mounts
- 9 The Art of Visual Observing
- 10 Visual Observations of the Moon and Planets
- 11 Imaging the Moon and Planets
- 12 Observing and Imaging the Sun
- 13 Observing and Imaging with an Astro-Video Camera
- 14 DSLR Deep-Sky Imaging
- 15 Imaging with Cooled CCD Cameras
- 16 Auto-Guiding and Drift Scan Alignment
- 17 Spectral Studies
- 18 Improving and Enhancing Images in Photoshop
- Index
- Plate Section
7 - Telescope Accessories
Finders, Eyepieces and Binoviewers
Published online by Cambridge University Press: 05 June 2014
- Frontmatter
- Dedication
- Contents
- Preface
- Acknowledgements
- Prologue A Tale of Two Scopes
- 1 Telescope and Observing Fundamentals
- 2 Refractors
- 3 Binoculars and Spotting Scopes
- 4 The Newtonian Telescope and Its Derivatives
- 5 The Cassegrain Telescope and Its Derivatives
- 6 Telescope Maintenance, Collimation and Star Testing
- 7 Telescope Accessories
- 8 Telescope Mounts
- 9 The Art of Visual Observing
- 10 Visual Observations of the Moon and Planets
- 11 Imaging the Moon and Planets
- 12 Observing and Imaging the Sun
- 13 Observing and Imaging with an Astro-Video Camera
- 14 DSLR Deep-Sky Imaging
- 15 Imaging with Cooled CCD Cameras
- 16 Auto-Guiding and Drift Scan Alignment
- 17 Spectral Studies
- 18 Improving and Enhancing Images in Photoshop
- Index
- Plate Section
Summary
This chapter covers the two major accessories that are used with virtually all telescopes – finders and eyepieces – along with some possible upgrades, such as an improved focuser. A finder and, usually, a pair of eyepieces are supplied with all telescope/mount packages, but if an optical tube assembly is being bought by itself these may not be provided, so allowing you to choose those that will fit your needs best. When coupled with a 2-inch wide-field eyepiece, the short-focal-length refractors that are now in common use have sufficiently large fields of view that a finder may well not be needed. With the increasing use of computerised ‘go-to’ mounts a finder will be used only during the initial alignment on bright stars. This has made it possible for finders without ‘magnitude gain’ (i.e., not employing a small telescope) to be commonly used.
Over the years, telescope eyepieces have become increasingly sophisticated – but also more expensive. It is now very easy to spend more on a high-quality eyepiece than the initial cost of a telescope, particularly if it is bought second-hand, and this rather goes against the grain. It was only after I had spent a large sum buying my Takahashi fluorite refractor that I felt justified in spending a significant amount on eyepieces. They did not then seem quite so expensive! One general point with respect to eyepieces: the simple eyepieces that are often provided with beginner’s telescopes, perhaps with just three elements, are not necessarily of low quality. The fact that fewer glass elements are used can be a good thing, in that there are fewer internal interfaces between the optical elements themselves and the air surrounding them, so minimising scatter and light absorption and thus giving higher-contrast images. ‘Simple’ eyepieces are much prized by planetary observers for whom contrast is so important. Their only real loss as compared with premium eyepieces is the fact that the available field of view will be smaller.
- Type
- Chapter
- Information
- An Amateur's Guide to Observing and Imaging the Heavens , pp. 100 - 118Publisher: Cambridge University PressPrint publication year: 2014