Meade LXD55 instruction manual

Page 42

Note: A small paper ring is attached to the primary mir- ror. This ring was attached at the factory for purposes of laser collimation. The ring will not diminish your tele- scope's imaging capabilities and does not need to be removed.

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Fig. 32: Correct (1) and incorrect (2) collimation as viewed during a star test.

4.Perform an actual star test to confirm the accuracy of steps 1 through 3. Using the SP 26mm eyepiece, point the telescope at a moderately bright (second or third mag- nitude) star, and center the image in the main telescope's field of view.

5.Bring the star's image slowly in and out of focus until you see several disks sur- rounding the star's center. If steps 1 through 3 were done correctly, you will see con- centric (centered with respect to each other) circles (1, Fig. 32).

An improperly collimated instrument will reveal oblong or elongated circles (2, Fig. 32). Adjust the 3 collimating screws on the primary mirror housing until the circles are concentric on either side of the focus.

In summary, the 4 adjustment screws on the plastic diagonal mirror housing change the tilt of the secondary mirror so that it is correctly centered in the focuser draw- tube, and so that the primary mirror appears centered when looking into the focuser. The 3 collimating knobs on the primary mirror change the tilt of the primary mirror so that it reflects the light directly up the center of the drawtube.

Alignment (Collimation) of the Schmidt-Cassegrain Optical System

The optical collimation (alignment) of any astronomical telescope used for serious purposes is important, but in the case of the Schmidt-Cassegrain design of the model SC-8, such collimation is absolutely essential for good performance. Take special care to read and understand this section well so that your model SC-8will give you the best optical performance.

As part of final optical testing, every Meade Schmidt-Cassegrain is precisely colli- mated at the Meade factory before shipment. However, vibrations in shipping can cause the optical system to become misaligned. Re-aligning the optics is, however, a straightforward process.

To check the collimation of your SC-8, center a bright star that is overhead, or use a “hot spot” of reflected Sunlight from a chrome car bumper, with the supplied 26mm eyepiece. Allow the telescope to adjust to the temperature of your observation site before proceeding; temperature differences between the optics and the outside air can cause distortion in the images.

With the star or hot spot centered, de-focus the image. You will notice that the out of focus star image looks like a ring of light surrounding a dark central spot; the dark cen- tral spot is in fact the shadow of the secondary mirror. Turn the focus knob until the ring of light fills about 10% of the eyepiece field-diameter. If the dark central spot is offset in (i.e., not concentric with) the ring of light, your telescope’s optical system is misaligned and requires collimation.

Follow these steps for collimation of the optical system:

a.The only adjustments possible, or necessary, on the SC-8 models are from the three screws (Fig. 33b) located at the edge of the outer surface of the secondary mirror housing.

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Contents Meade Instruments Corporation Page Contents Telescope Features 1 1% g f e$2% LXD55-SeriesYour Personal Window to the Universe Computer Control Panel see e LXD55 Tips Autostar Features FeaturesTour the Cosmos with Just the Push of a Button Tip Accessories How to Assemble Your TelescopeTelescope Assembly Getting StartedViewfinder assembly Schmidt-Newtonian models Balancing the Telescope Insert eyepiece into holder and tighten thumbscrewsAligning the Viewfinder Choosing an EyepieceToo Much Power? Observing by Moving the Telescope ManuallyActivate the Arrow Keys Autostar Models Only Slew Speeds Autostar Models OnlyTracking Objects Setting the Polar Home PositionObserve the Moon 16bObserve a Star using the Automatic Tracking Feature Using Autostars GO to Capabilities Autostar Models OnlyMoving Through Autostar’s Menus Autostar Models Only Initializing Autostar Autostar Models OnlyTraining the Drive Autostar Models Only Easy Alignment Autostar Models Only Go To Saturn Autostar Models OnlyUsing the Guided Tour Autostar Models Only Planet Saturn is over 800 million miles from the EarthAutostar Navigation Exercise To Calculate Sunset timeEntering Data into Autostar Navigating AutostarAutostars Menus Select Item ObjectMenus Object MenuUtilities Menu Event MenuGlossary Menu LXD55-SeriesSetup Menu EnterObserving Considerations Setup Menu Daylight SAVING, Surf the Web Adding Observing Sites To Add a Site to the user-defined site listTo Edit a Site Using Autostar to Find Objects Not in the Libraries To GO to a user-entered objectObserving Satellites LandmarksTo Add a landmark to the database To Check on the Available Memory To Select a landmark from the databaseTo perform a Landmark Survey Photography Few tips on photography with the LXD55-SeriestelescopesOptional Accessories 10 f/4Series 4000 Photo-Visual Page Maintenance General MaintenanceD e f g Page Defocused star images. Misaligned 1, 2, Aligned Meade Customer Service Inspecting the OpticsSpecifications 5 Model SN-6, SN-6EC Specifications4 Model SN-8, SN-8EC Specifications 10 f/4 Model SN-10 Specifications 9.3 Model AR-5, AR-5EC Specifications8 Model AR-6 Specifications 10 Model SC-8 Specifications Autostar SpecificationsAutostar Dimensions Setting Circles Appendix a Celestial CoordinatesOne-Star Polar Alignment Locating the Celestial PoleOne- and Two-Star Polar Alignment Two-Star Polar AlignmentPolar Alignment Viewfinder Axis Alignment ProcedureProcedure #1 To correct for attitude misalignment Method 1 Manual AlignmentProcedure #2 To correct for elevation misalignment Position aStar Charts TipsMethod 2 Axis Alignment Using Autostar City State/Prov./Country Latitude Appendix C Latitude ChartLatitude Chart for Major Cities of the World City Country LatitudeAppendix D EC Handbox To move the telescope using the Electronic Controller Modes of OperationSlew Speeds Tracking Rates Changing the Polar Mode Optional Autostar Computer Controller for LXD55 EC UsersHow to Attach the Optical Tube to the Mount Mounting the SC bracket and optical tube to the mountObjects in Space Appendix F Basic AstronomyAutostar Glossary MoonPlanets Deep-Sky ObjectsFurther Study Page Meade Instruments Corporation
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