How to Check the Collimation of the Optical System of Your Meade Lightbridge Truss Tube Dobsonian Telescope

By eHow Electronics Editor

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The Meade Lightbridge Truss Tube Dobsonian Telescope is a great sky-viewing instrument. If your telescope is bumped or treated roughly, you will probably need to adjust the collimation or mirror alignment of the unit. Here's how to check the collimation of the optical system on this telescope.

Instructions

Difficulty: Moderate

Step1
Make sure the base is resting on the rubber feet, which should be on the floor.
Step2
Verify that the entire assembly will move easily up and down.
Step3
Verify that the entire assembly will move easily left and right.
Step4
Verify that the eyepiece is installed on the telescope.
Step5
Check the focuser and make sure the open end of the telescope is to your left.
Step6
Verify that the reflection of the primary mirror is in the middle of the surface of the diagonal mirror. If not, adjust the collimation screws in the diagonal mirror housing until it is centered.
Step7
View through the focuser and make sure that the reflection of the diagonal mirror is centered in the reflection of the primary mirror. If not, adjust the collimation screws located at the rear of the primary mirror.
Step8
Verify that your adjustments are correct by focusing on a secondary star.
Step9
Bring the focus in and out on the telescope. If you see concentric circles, the collimation was successful. If you see oblong or elongated circles, you will need to repeat the steps above.

Tips & Warnings

  • Utilize only finger strength to tighten and adjust the truss knobs. Overtightening can cause stripping and other damage to occur.
  • Never adjust the screws farther than two turns. A quarter-turn on the collimation screws will make significant adjustments to the alignment of the unit.
  • Don't overtighten the bolts on the system. Overtightening the bolts can strip the threads and you will have to reorder the screws or the inserts from the factory.

Comments

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rboston said

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on 6/2/2008 For Step #6 & #7, do I take the EP out of the focuser to accomplish these steps?

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eHow Article:  How to Check the Collimation of the Optical System of Your Meade Lightbridge Truss Tube Dobsonian Telescope

eHow Electronics Editor

eHow Electronics Editor

Category: Electronics

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