Celestron CR-150 HD 1 1/4 Accessory, Focuser Tension, Built-inT-Adapter, Screw, Thread

Page 21

1 1/4" Accessory

Eyepieces are commonly referred to by focal length and barrel diameter. The focal length of each eyepiece is printed on the eyepiece barrel. The longer the focal length (i.e.,thelargerthenumber) thelowertheeyepiecemagnification(i.e.,power)andthe shorter the focal length (i.e., the smaller the number) the higher the magnification. Generally,youwilluselow-to-moderatepowerwhenviewing. Formoreinformation onhowtodeterminepower,seethesectionon“CalculatingMagnification.”

Barrel diameter is the diameter of the barrel that slides into the star diagonal or accessory adapter. Your CR-150 HD refracting telescope can use eyepieces with both a 1-1/4" barrel diameter and 2" barrel diameter. To use a 2" barrel eyepiece, the 1 1/4" accessory adapter must first be removed. To do this, simply loosen the two chrome thumbscrews located around the focuser barrel (see figure 4-1) and remove the 1 1/4" adapter. Once removed, a 2" eyepiece or accessory can be inserted directly into the focuser barrel and secured with the two thumb screws.

		1 1/4" Accessory	Focuser Tension
		Adapter	Focuser Tension
	Built-inT-Adapter	Adapter	Screw
	Built-inT-Adapter		Screw
	Thread

2" Focuser
Barrel	FocuserKnob

	Figure 4-1

Telescope Basics • 21

Image 21

Contents Model #21017 The CR-150HD6 Refractor T A B L E O F C O N T E N T S ii Table of ContentsAssembling the CG-5Equatorial Mount Table of Contents Using the Lens Cap Aperture Stop4 Introduction I N T R O D U C T I O NIntroduction How to Use This Manual AWordofCautionThe Refractor Optical System The Mount6 Introduction Unpacking Your CR-150HD A S S E M B L I N G Y O U R C R - 1 5 0 H DThe CR-150HD Setting Up the Tripod Adjusting the Tripod Height Assembling the CG-5Equatorial MountTripod Head 10 The CR-150HD Attaching the Accessory TrayAttaching the Equatorial Mount 12 The CR-150HD Attaching the R.A. Slow Motion KnobAttaching the Declination Slow Motion Knob 14 The CR-150HD 1.Lock the DEC clamp to hold the mount in placeTube Rings Dovetail Bracket Attaching the Telescope to the Mount16 The CR-150HD Balancing the Telescope in R.ACOMPLETELY Balancing the Telescope in DECAdjusting the Mount in Altitude Adjusting the Mount in Azimuth18 The CR-150HD Disassembling and Transporting Your CR 150 HD Technical SpecificationsStoring Your CR- 150 HD OPTICAL TUBET E L E S C O P E B A S I C S Attaching the AccessoriesThe Star Diagonal The EyepieceFocuser Tension 1 1/4 AccessoryAdapter Built-inT-AdapterFocusing Attaching the Finder22 Telescope Basics Aligning the Finder YourFirstLook Image OrientationDaytimeObserving NEVER POINT YOUR TELESCOPE AT THE SUN UNLESSNighttime Observing Calculating Magnification Determining Field of View26 Telescope Basics 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.” A S T R O N O M Y B A S I C S The Celestial Coordi- nate System28 Astronomy Basics Astronomy Basics Motion of the StarsEquator Polar AlignmentDefinition 30 Astronomy BasicsFinding the Pole 32 Astronomy Basics Latitude ScalesPointingatPolaris 34 Astronomy Basics DeclinationDriftPolar Alignment Finders Aligning the R.A Setting CircleObserving the Observing the MoonPlanets C E L E S T I A L O B S E R V I N GObserving the Sun Using the Lens Cap Aperture StopSOLAROBSERVINGHINTS Celestial ObservingUsing the Setting Circles Observing Deep-SkyObjects38 Celestial Observing StarHopping 40 Celestial Observing Transparency Viewing ConditionsSky Illumination Seeing42 Celestial Observing Celestial Photography C E L E S T I A L P H O T O G R A P H YLunar Phase Short Exposure Prime FocusCrescent 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 46 Celestial Photography PiggybackEktar 1000 color print Konica 3200 color print 48 Celestial Photography Projection PhotographyCare and Cleaning of the Optics T E L E S C O P E M A I N T E N A N C ETelescope Maintenance O P T I O N A L A C C E S S O R I E S 50 Optional AccessoriesDual Axis Drive System - #93523 Super Modified Achromatic SMA EyepiecesOptional Accessories Motor Drive System - #93518 52 Optional AccessoriesNGC# THEMESSIERCATALOGConst Type54 The Messier Catalog Const Epoch LIST OF BRIGHT STARSStar Name ConstellationAstronomy Texts FOR FURTHER READINGAtlases General Observational AstronomyCELESTRON ONE YEAR WARRANTY Celestron International 2835 Columbia Street Torrance, CA Tel FaxItem #21017-INST Price $10.00