Digital SLR Astrophotography (Practical Amateur Astronomy)

235 Pages·2007·3.87 MB·English

by  Michael A. Covington

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PracticalAmateurAstronomy
DigitalSLRAstrophotography
Inthelastfewyears,digitalSLRcamerashavetakentheastrophotographyworldby
storm.Itisnoweasiertophotographthestarsthaneverbefore!Theyarecompactand
portable,easytocoupletospeciallensesandalltypesoftelescopes,andaboveall,
DSLRcamerasareeasyandenjoyabletouse.Inthisconciseguide,experienced
astrophotographyexpertMichaelCovingtonoutlinesthesimple,enduringbasicsthat
willenableyoutogetstarted,andhelpyougetthemostfromyourequipment.He
coversawiderangeofequipment,simpleandadvancedprojects,technical
considerations,andimageprocessingtechniques.Unlikeotherastrophotography
books,thisonefocusesspecificallyonDSLRcameras,notastronomicalCCDs,
non-DSLRdigitalcameras,orfilm.Thisguideisidealforastrophotographerswhowish
todeveloptheirskillsusingDSLRcamerasandasafriendlyintroductiontoamateur
astronomersorphotographerscuriousaboutphotographingthenightsky.Further
information,usefullinks,andupdatesareavailablethroughthebook’ssupporting
website,www.dslrbook.com.
Michael Covington,anavidamateurastronomersinceage12,hasdegreesin
linguisticsfromCambridgeandYaleUniversities.Hedoesresearchoncomputer
processingofhumanlanguagesattheUniversityofGeorgia,wherehisworkwonfirst
prizeintheIBMSupercomputingCompetitionin1990.Hiscurrentresearchand
consultingareasincludecomputersinpsycholinguistics,naturallanguageprocessing,
logicprogramming,andmicrocontrollers.Althoughacomputationallinguistby
profession,heisrecognizedasoneofAmerica’sleadingamateurastronomersandis
highlyregardedinthefield.Heisauthorofseveralbooks,includingthehighly
acclaimedAstrophotographyfortheAmateur(1985,SecondEdition1999),CelestialObjects
forModernTelescopes(2002)andHowtoUseaComputerizedTelescope(2002),whichareall
publishedbyCambridgeUniversityPress.Theauthor’sotherpursuitsincludeamateur
radio,electronics,computers,ancientlanguagesandliteratures,philosophy,theology,
andchurchwork.HelivesinAthens,Georgia,USA,withhiswifeMelodyand
daughtersCathyandSharon,andcanbevisitedonthewebat
www.covingtoninnovations.com.

Practical Amateur Astronomy
Digital SLR Astrophotography
Michael A. Covington
CAMBRIDGEUNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 8RU, UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521700818
© M. A. Covington 2007
This publication is in copyright. Subject to statutory exception and to the provision of
relevant collective licensing agreements, no reproduction of any part may take place
without the written permission of Cambridge University Press.
First published in print format 2007
ISBN-13 978-0-511-37853-9 eBook (NetLibrary)
ISBN-13 978-0-521-70081-8 paperback
Cambridge University Press has no responsibility for the persistence or accuracy of urls
for external or third-party internet websites referred to in this publication, and does not
guarantee that any content on such websites is, or will remain, accurate or appropriate.
SoliDeogloria

Contents
Preface pagexiii
Part I Basics 1
1
TheDSLRrevolution 3
1.1 WhatisaDSLR? 3
1.2 ChoosingaDSLR 6
1.2.1 Majormanufacturers 6
1.2.2 Shoppingstrategy 7
1.3 Choosingsoftware 8
1.3.1 Photoediting 9
1.3.2 Astronomicalimageprocessing 9
1.3.3 Freeware 9
1.3.4 Judgingsoftwarequality 10
1.4 IsaDSLRrightforyou? 10
1.5 Isfilmdeadyet? 12
2
Maintechnicalissues 14
2.1 Imagefiles 14
2.1.1 Filesize 14
2.1.2 Rawvs.compressedfiles 14
2.1.3 “Digitalfilm”andcamerasoftware 15
2.2 Focusing 15
2.3 Imagequality 16
2.3.1 Combiningimages 16
2.3.2 Overcomingskyfog 16
2.3.3 Dark-framesubtraction 16
2.3.4 TheNikon“stareater” 17
2.3.5 Grain 17
2.4 Sensorsizeandmultiplier(zoomfactor) 19
2.5 Dustonthesensor 19
vii
Contents
2.6 ISOspeedsettings 21
2.7 Noreciprocityfailure 21
2.8 Howcolorisrecorded 22
2.8.1 TheBayermatrix 22
2.8.2 Low-passfiltering 23
2.8.3 TheFoveon 23
2.9 Nebulaeareblueorpink,notred 23
3
Basiccameraoperation 26
3.1 Takingapicturemanually 26
3.1.1 Shutterspeedandaperture 26
3.1.2 Manualfocusing 26
3.1.3 ISOspeed 28
3.1.4 Whitebalance 28
3.1.5 Doyouwantanautomaticdarkframe? 29
3.1.6 Trippingtheshutterwithoutshakingthetelescope 30
3.1.7 Mirrorvibration 30
3.1.8 Vibration-reducinglenses 32
3.2 Thecameraasyourlogbook 32
3.3 Limitinglightemissionfromthecamera 33
3.4 Menusettings 33
3.4.1 Thingstosetonceandleavealone 33
3.4.2 Settingsforanastrophotographysession 34
3.4.3 UsingNikonMode3 35
3.5 Determiningexposures 35
3.6 Cool-downbetweenlongexposures 36
4
Foursimpleprojects 38
4.1 TelephotoMoon 38
4.2 AfocalMoon 39
4.3 Starsfromafixedtripod 40
4.4 Piggybacking 44
4.5 Goingfurther 45
Part II Cameras,lenses,andtelescopes 47
5
Couplingcamerastotelescopes 49
5.1 Opticalconfigurations 49
5.1.1 Typesoftelescopes 49
5.1.2 Typesofcoupling 50
5.2 Fittingitalltogether 53
5.3 Opticalparameters 55
5.3.1 Focallength 55
5.3.2 Aperture 56
5.3.3 f-ratioandimagebrightness 56
viii