How to Check the Collimation of the Optical System of Your Meade 8-inch Lightbridge Truss Tube Dobsonian Telescope

The Meade 8-inch Lightbridge Truss Tube Dobsonian Telescope is a great sky-viewing instrument. But 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.

Instructions

Difficulty: Moderate

1. Make sure the base is resting on the rubber feet, which should be on the floor.
2. Verify that the entire assembly will move easily up and down.
3. Verify that the entire assembly will move easily left and right.
4. Verify that the eyepiece is installed on the telescope.
5. Check the focuser and make sure the open end of the telescope is to your left.
6. Verify that the reflection of the primary mirror is in the middle of the surface of the diagonal mirror. If not, adjust with the collimation screws in the diagonal mirror housing until it is centered.
7. 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.
8. Verify that your adjustments are correct by focusing on a secondary star.
9. 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.

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