Celestron CR-150 HD T E L E S C O P E B A S I C S, Attaching the Accessories, The Star Diagonal

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T E L E S C O P E B A S I C S

T E L E S C O P E B A S I C S

Attaching the Accessories

Once your telescope has been fully assembled, you are ready to attach the accessories and have a look. This section deals with basic telescope opera- tions that are common to all Celestron refractor telescopes.

There are several accessories that come standard with all the Celestron refractor telescopes. The installation and use of each of these is described in this section.

The Star Diagonal

The star diagonal uses a mirror that reflects the light at a right angle to the light path of the telescope. This allows you to observe in positions that are physi- cally more comfortable than if you were to look straight through. To attach the star diagonal:

1.Turn the set screw on the accessory adapter until it no longer extends into (i.e., obstructs) its inner diameter of the visual back.

2.Slide the chrome portion of the star diagonal into the accessory adapter (see figure4-1).

3.Tighten the set screw to hold the star diagonal in place.

If you wish to change the orientation of the star diagonal, loosen the set screw on the visual back until the star diagonal rotates freely. Rotate the diagonal to the desired position and tighten the set screw.

The Eyepiece

The eyepiece, or ocular, is an optical element that magnifies the image focused by the telescope. The eyepiece(s) fits into either the accessory adapter directly , the star diagonal, or an erect image diagonal (see Optional Accessories section). To attach an eyepiece:

1.Loosen the set screw on the star diagonal so that it does not obstruct the inner diameter of the eyepiece end of the diagonal.

2.Slide the chrome portion of the eyepiece into the star diagonal (see figure 4-1).

3.Tighten the set screw to hold the eyepiece in place.

To remove the eyepiece, loosen the set screw on the star diagonal and slide the eyepiece out. You can then replace it with another ocular.

20 • Telescope Basics

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Contents 6 Refractor Model #21017The CR-150HD Assembling the CG-5Equatorial Mount T A B L E O F C O N T E N T Sii Table of Contents Using the Lens Cap Aperture Stop Table of ContentsI N T R O D U C T I O N 4 IntroductionHow to Use This Manual AWordofCaution Introduction6 Introduction The Refractor Optical SystemThe Mount A S S E M B L I N G Y O U R C R - 1 5 0 H D Unpacking Your CR-150HDThe CR-150HD Tripod Head Setting Up the Tripod Adjusting the Tripod HeightAssembling the CG-5Equatorial Mount Attaching the Accessory Tray 10 The CR-150HDAttaching the Equatorial Mount Attaching the R.A. Slow Motion Knob 12 The CR-150HDAttaching the Declination Slow Motion Knob 1.Lock the DEC clamp to hold the mount in place 14 The CR-150HDAttaching the Telescope to the Mount Tube Rings Dovetail BracketBalancing the Telescope in R.A 16 The CR-150HDBalancing the Telescope in DEC COMPLETELY18 The CR-150HD Adjusting the Mount in AltitudeAdjusting the Mount in Azimuth Technical Specifications Disassembling and Transporting Your CR 150 HDStoring Your CR- 150 HD OPTICAL TUBEAttaching the Accessories T E L E S C O P E B A S I C SThe Star Diagonal The Eyepiece1 1/4 Accessory Focuser TensionAdapter Built-inT-Adapter22 Telescope Basics FocusingAttaching the Finder Aligning the Finder Image Orientation YourFirstLookDaytimeObserving NEVER POINT YOUR TELESCOPE AT THE SUN UNLESSNighttime Observing 26 Telescope Basics Calculating MagnificationDetermining Field of View GeneralPhotographyHints Your Celestron telescope can be used for both terrestrial and astronomical photography. Your telescope has a fixed aperture and, as a result, a fixed f/ratio. To properly expose your subjects photographically, you need to set your shutter speed accordingly. Most 35mm single lens reflex SLR cameras offer through-the-lens metering that lets you know if your picture is under or overexposed. This is important for terrestrial photography where exposure times are measured in fractions of a second. In astrophotography, the exposures are much longer, requiring that you use the “B” setting on your camera. The actual exposure time is determined by how long you keep the shutter open. More on this in the section on “Celestial Photography.” 28 Astronomy Basics A S T R O N O M Y B A S I C SThe Celestial Coordi- nate System Motion of the Stars Astronomy BasicsPolar Alignment EquatorDefinition 30 Astronomy BasicsFinding the Pole Latitude Scales 32 Astronomy BasicsPointingatPolaris DeclinationDrift 34 Astronomy BasicsAligning the R.A Setting Circle Polar Alignment FindersObserving the Moon Observing thePlanets C E L E S T I A L O B S E R V I N GUsing the Lens Cap Aperture Stop Observing the SunSOLAROBSERVINGHINTS Celestial Observing38 Celestial Observing Using the Setting CirclesObserving Deep-SkyObjects StarHopping 40 Celestial Observing Viewing Conditions TransparencySky Illumination Seeing42 Celestial Observing C E L E S T I A L P H O T O G R A P H Y Celestial PhotographyShort Exposure Prime Focus Lunar PhaseCrescent QuarterThe exposure times listed here should be used as a starting point. Always make exposures that are longer and shorter than the recommended time. Also, try bracketing your exposures, taking a few photos at each shutter speed. This will ensure that you will get a good photo. If using black and white film, try a yellow filter to reduce the light intensity and to increase contrast Piggyback 46 Celestial PhotographyEktar 1000 color print Konica 3200 color print Projection Photography 48 Celestial PhotographyTelescope Maintenance Care and Cleaning of the OpticsT E L E S C O P E M A I N T E N A N C E 50 Optional Accessories O P T I O N A L A C C E S S O R I E SDual Axis Drive System - #93523 Super Modified Achromatic SMA EyepiecesOptional Accessories 52 Optional Accessories Motor Drive System - #93518THEMESSIERCATALOG NGC#Const Type54 The Messier Catalog NGC# LIST OF BRIGHT STARS EpochStar Name ConstellationFOR FURTHER READING Astronomy TextsAtlases General Observational AstronomyCELESTRON ONE YEAR WARRANTY Item #21017-INST Price $10.00 Celestron International 2835 Columbia StreetTorrance, CA Tel Fax