Patrick Moore s Practical Astronomy Series

Transcription

1 Patrick Moore s Practical Astronomy Series For further volumes:

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3 Amateur Telescope Making in the Internet Age Finding Parts, Getting Help, and More Robert L. Clark 123

4 Robert L. Clark Westminster, MD 21157, USA ISSN ISBN e-isbn DOI / Springer New York Dordrecht Heidelberg London Library of Congress Control Number: Springer Science+Business Media, LLC 2011 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed on acid-free paper Springer is part of Springer Science+Business Media (

5 Acknowledgments Many people should share in the credit or blame for this book, some for direct contributions and some for encouragement and support of the activities leading up to this book. Of the first group my wife, Nancy, tolerated lots of things not getting done as time went to the book. She copied files and pictures, providing needed technical support. Gerry Frishkorn from the Westminster Astronomical Society provided the neat photo of a spider from his famous binoculars. He also checked and detected errors in my math. Numerous folks from the same club provided leads for the supplier appendix. Cousins Ann Herbert and Faith Marchal provided help with the conversion material. Cousin Hughes Gemmill gave me some old Dallmeyer lenses with which I learned how to get them unglued and cleaned. In the second group are Duane Shie, who is inspiring as a dumpster diver; George Lockwood, who was always available for idea testing and ebay hints; Teresa Rosales; Blas Chavez; Roger Baker; and Mark Dennis, who helped with the lugging of telescopes and their parts. The folks at Springer publishing have been very tolerant of the questions of a beginning author and have provided important guidelines. v

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7 Contents 1 Introduction... 1 Tools... 3 AbsolutelyNecessary... 3 VeryHelpfulorNecessaryforParticularTasks... 3 NicetoHave... 3 Ergonomics What s Not Included in this Book General Advice SafetyTips To Buy or Build a Telescope Telescope Types and Designs Telescope Types Reflector Telescopes Refractor Telescopes Telescope Design Considerations A Real Simple Telescope Build a Good Copyscope The Small Copyscope OpticalParts Mechanical Parts The Medium Copyscope OpticalParts Mechanical Parts The Large Copyscope OpticalParts vii

8 viii Contents Mechanical Parts How to Make Your Copyscope Focal Length Alignment Mounting a Copyscope The 80 mm Refractor Telescope Description and Capabilities Specifications and Components Newtonian Telescopes Typical Newtonian Telescopes TheObjectiveMirror MirrorMounting A Spider in Your Telescope MirrorCells Simple Collimation The F17 4-Inch Refractor The Rotating Star Diagonal The Back Two Bulkheads The Diagonal Mirror MountingtheRefractorUsingaCradle Focusers, Eyepieces, Barlows, and Finders Focusers Telescoping Tubes RackandPinionDesign HelicalDesign CrayfordDesign Eyepieces EyeRelief Exit Pupil Achromats Very Modern Wide Angle Eyepieces Compound Projection and Camera Lenses BarlowLenses ImageInverter(ErectingLens) Finders Requirements for a Workable Finder Scope Satisfying the Finder Requirements Peep Sight Finder Laser Pointer as a Finder Tubes Closed Tube Approaches Wooden Tubes

9 Contents ix Getting Started AssemblyoftheTube UsingGussets Wood Tubes Without Gussets Open Tubes Truss Tubes Building a 12.5-Inch Newtonian with Rotating Cage DimensionsoftheTube(Box) Diagonal Spider Upper Tube Rotation Doughnuts to Preserve Alignment Stabilizers Mounting Ergonomic Mounts Mounting Types Supports Balance and Moment Wedges An Ergonomic Altazimuth Mount Evaluation, Quality Testing, and Optical Aberrations HowGoodDoesItNeedtoBe? CommonFaults Focal Length Quality Testing PossibleConstructionProblems Lenses Mirrors Mirror Reflective Coatings Optical Quality Terminology Wavelength-Based Measurements RaysandWaves Scratch and Dig Optical Surface Specifications Scatter (Spot) Diagrams StrehlRatio Quality of Flat Mirrors TestingaFlat OpticalAberrations QuickandEasyTests Junk Collecting and Working with Modern Materials Junk Collection (Creative Cross Utilization) LensRestoration/UsedLenses LensCementing

10 x Contents Getting a Lens Apart Polishing and Coating Ideas NoDrag,NoProgress HowLongWillItTake? LapMaking WorkingwithPVCPipe PVC Eyepiece Canisters ForNCanisters OtherUsesforPVC AligningParts Telescope Mounts LensCells RetainingRings Floor Underlay GluesandCements Appendix I Web Suppliers of Telescope Building Parts and Materials Alphabetical Listing of Suppliers Products Supplier Codes by Product Appendix II Telescope-Building Books and Websites BookMust-Haves Magazines Websites Appendix III Polishing Log Appendix IV Units and Conversions General Conversions WoodStockandHardwareConversions European Plywood Standards Timber Hardware Index

11 About the Author Although Clark was born in New Hampshire, he spent his early teen years in the New York City area. There he became acquainted with the Theodore Roosevelt Museum of Natural History and at the associated Hayden Planetarium, operated, at that time, by Newton and Margaret Mayhall. Their book Skyshooting provided his first introduction to the idea that someone with only moderate skills can build good scientific instruments. The three volumes of Amateur Telescope Making, edited by Albert G. Ingalls, completed the process of addiction. Clark received a B.S. degree in Mathematics from Stanford University. He then served in the US. Air Force at Strategic Air Command headquarters in Nebraska. After his discharge he did graduate work in Mathematics and Computer Science at the University of Maryland. After a few years spent in the Military Operations Research industry, he migrated to a university teaching position that lasted 33 years at the University of the District of Columbia. Throughout all this time he continued to be enamored by the process of building telescopes and actually built a few as time permitted. Since retirement he has allowed the addiction to occupy a large part of his enthusiasm, as is made evident by Fig Clark now resides in Westminster, Maryland, where he has built a hilltop observatory and is active with the Westminster Astronomical Society. xi