Patrick Moore’s Practical Astronomy Series Other titles in this series Telescopes and Techniques (2nd Edn.) Astronomy with Small Telescopes Chris Kitchin Stephen F. Tonkin (Ed.) The Art and Science of CCD Astronomy Solar Observing Techniques David Ratledge (Ed.) Chris Kitchin The Observer’s Year Observing the Planets Patrick Moore Peter T. Wlasuk Seeing Stars Light Pollution Chris Kitchin and Robert W. Forrest Bob Mizon Photo-guide to the Constellations Using the Meade ETX Chris Kitchin Mike Weasner The Sun in Eclipse Practical Amateur Spectroscopy Michael Maunder and Patrick Moore Stephen F. Tonkin (Ed.) Software and Data for Practical Astronomers More Small Astronomical Observatories David Ratledge Patrick Moore (Ed.) Amateur Telescope Making Observer’s Guide to Stellar Evolution Stephen F. Tonkin (Ed.) Mike Inglis Observing Meteors, Comets, Supernovae and How to Observe the Sun Safely other Transient Phenomena Lee Macdonald Neil Bone The Practical Astronomer’s Deep-Sky Astronomical Equipment for Amateurs Companion Martin Mobberley Jess K. Gilmour Transit: When Planets Cross the Sun Observing Comets Michael Maunder and Patrick Moore Nick James and Gerald North Practical Astrophotography Observing Variable Stars Jeffrey R. Charles Gerry A. Good Observing the Moon Visual Astronomy in the Suburbs Peter T. Wlasuk Antony Cooke Deep-Sky Observing Astronomy of the Milky Way: The Observer’s Steven R. Coe Guide to the Northern and Southern Milky Way AstroFAQs (2 volumes) Stephen Tonkin Mike Inglis The Deep-Sky Observer’s Year The NexStar User’s Guide Grant Privett and Paul Parsons Michael W. Swanson Field Guide to the Deep Sky Objects Observing Binary and Double Stars Mike Inglis Bob Argyle (Ed.) Choosing and Using a Schmidt-Cassegrain Navigating the Night Sky Telescope Guilherme de Almeida Rod Mollise The New Amateur Astronomer Martin Mobberley Care of Astronomical Telescopes and Accessories A Manual for the Astronomical Observer and Amateur Telescope Maker M. Barlow Pepin With 82 Figures All illustrations in this book are by the author, unless otherwise noted. British Library Cataloguing in Publication Data Pepin, M. Barlow Care of astronomical telescopes and accessories : a manual for the astronomical observer and amateur telescope maker. (Patrick Moore’s practical astronomy series) 1. Telescopes–Maintenance and repair I. Title 522.2′0288 ISBN 185233715X Library of Congress Cataloging-in-Publication Data Pepin, M. Barlow. Care of astronomical telescopes and accessories : a manual for the astronomical observer and amateur telescope maker / M. Barlow Pepin. p. cm. — (Patrick Moore’s practical astronomy series, ISSN 1617-7185) Includes bibliographical references and index. ISBN 1-85233-715-X (pbk. : alk. paper) 1. Telescopes–Amateur’s manuals. I. Title. II. Series. QB88.P46 2004 522.2–dc22 2004049148 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be repro- duced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. Patrick Moore’s Practical Astronomy Series ISSN 1617-7185 ISBN 1-85233-715-X Springer-Verlag London Berlin Heidelberg Springer Science+Business Media springeronline.com © Springer-Verlag London Limited 2005 Printed in the United States of America The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and there- fore free for general use. The publisher makes no representation, express or implied, with regard to the accuracy of the infor- mation contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Observing the Sun, along with a few other aspects of astronomy, can be dangerous. Neither the publisher nor the author accepts any legal responsibility or liability for per- sonal loss or injury caused, or alleged to have been caused, by any information or recommendation contained in this book. Typeset by EXPO Holdings, Malaysia 58/3830-543210 Printed on acid-free paper SPIN 10901120 To my Sun and Stars: Mary, Danielle and Jeannette Foreword Many new books about astronomical telescopes are published each year, but this one, by M. Barlow Pepin, is unlike any other – at least as far as I know. The emphasis has shifted lately. Amateur telescope making is less popular than it used to be because professionally made telescopes are much cheaper than they were only a year or two ago. But there is no point in having a good telescope unless it is well cared for, and many observers pay too little attention to this. It is not only a question of common sense; expert guidance is also needed, and in this book M. Barlow Pepin gives it. He goes into detail with regard to all aspects of telescope care and maintenance, and even experienced observers will learn a great deal from it. Astronomy is one of the very few sciences in which amateurs can make valu- able contributions, but good, well-maintained equipment is essential. If you want to get the best out of your telescopes and other astronomical instruments, then this is the book for you. Sir Patrick Moore CBE, FRS vii Preface and Acknowledgments This book fills a gap left by earlier works of general practical advice, most of which are either out of date or long out of print. It is both a contribution and a tribute to its predecessors’ tradition of handing down craft knowledge. Although the volume distills years of practical experience working with astronomical equipment and accessories, it doesn’t pretend to be complete in every detail. It would have been illogical to try to set down everything about maintaining equip- ment for every branch of the pursuit. Such a work would fill an already groaning bookshelf. Furthermore, I don’t cover things I have no personal experience with – that’s what compendium works are for, and there are some good ones around that cover most aspects of amateur astronomy. Several are included in the Bibliography. Finally, experts continuously cover new developments in fast- changing fields like electronic imaging, optical fabrication methods, narrowband imaging and robotic systems. This work concentrates on the practical acquisition and maintenance of the optics and mechanics that support such endeavors. Despite the fabulous armchair journeys we can now make on the Internet, using optics under the sky is still what makes the pursuit of amateur astronomy enjoyable. Even the best astronomical equipment requires both care and appreci- ation to yield good results. Acquiring and caring for it takes patience and a few special skills. There is still time, place and a need for hands-on work. Years ago I carried a pencil sketch and part of a homemade mount into a machine shop and asked if they could make a simple modification. The foreman in blackened coveralls took a look and said, “Sure, come back tomorrow, it should cost you about twenty.” The last time I tried this, a fellow in a golfing shirt looked up from his computer and said, “Sure, send me a CAD file for our CNC guys, and we’ll work up a quote for next week. How many units do you need?” Just the software would have cost more than a new mount! The artisans aren’t gone, but they are increasingly hard to find. When you do, they are busier than the devil. Thus, all the more need for a work that covers a little history, with some basic fixes and workarounds for the practical amateur. That’s what Section II does. A few processes I have personally worked out and tested are outlined in Chapter 13. My hat is off as I write this, aware of the many individuals and groups whose collective knowledge is far greater than my own. It was fascinating to review the works of earlier authors around the world, many of whom lived at a time when a telescope was a rare commodity, and most equipment cobbled together in the garages and basements of dedicated enthusiasts. The mission here is the same as ix x Preface and Acknowledgments theirs: to impart some basics of contemporary instrument acquisition and main- tenance to new astronomers, and to provide a useful lookup resource for the old hands. There is always room for improvement. In fact, I fully expect to hear about matters that weren’t addressed. I wish to express sincere appreciation to my present editor John Watson. I am especially gratified for the opportunity here to acknowledge mentors such as series editor Sir Patrick Moore, the late solar observer Donald Trombino, FRAS and editors in the past, including Richard Berry who accepted my first efforts at publication, William J. Cook, Martin Neumann and Simon Mitton. For hints and help over the years I am indebted to Alan MacRobert, Roger Sinnott, supportive members of management and staff at Sky Publishing, and to the Astronomical League, the British Astronomical Society, the Royal Astronomical Society of Canada and the Vereinigung der Sternfreunde (VdS) of Germany. A wide range of amateur and professional optical historians, from Peter Abrahams to Drs. Albert van Helden and Wayne Orchiston, pointed the way to valuable references on historical techniques. Additionally, kudosto all the fine people on the business side whose hearts are in the right place, especially Al Nagler who gave open per- mission to use equipment of his design to illustrate a few basic instruments and accessories for the book. Thanks also to New Focus, Inc. of San Jose, California, and Aerotech, Inc. of Pittsburgh, Pennsylvania, for the loan of bench components for generating laser visualizations of light through the telescope, published before only as line drawings. Sincere regards to a host of observing companions too numerous to mention, and the many unseen folks, friendly voices in the dark from around the world. Here, too, is a nod to all amateurs’ patient spouses and offspring who have lain awake at night wondering “what could possibly be so interesting out there?” Finally, this volume is dedicated to fellow ATMs and Telescope Nuts, those people who insist on continuing to make contraptions out of odd glass and spare parts that rival or exceed the performance of the best manufactured equipment. The special community of amateur astronomers has endured for centuries. Our activities will doubtless continue long into the future as one of the most fascinat- ing pursuits in this or any other universe. If this volume eases the path for a few, or just helps to pass time on a cloudy night, it will have repaid the effort. M. Barlow Pepin Duncanville, Texas July, 2004 The author. Photo: L. Lattin.