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Mirror alignment and collimation

Collimation of your telescope will give you the best view of the night sky. This step-by-step, beginner’s guide shows you how.

Collimation is the process of aligning the optical components of the telescope. Correct alignment will give the optimal resolution (sharpness) and maximum light gathering for your stargazing sessions.

Also see my other beginner’s guides, including getting started with a new telescope, cleaning and centre spotting your primary mirror.

Guide based on the Celestron AstroMaster 130EQ, but the same principals apply to all reflector telescopes.

Full mirror alignment and collimation guide

Time needed: 50 minutes

These steps are broken down into key stages. Follow the link to each guide in turn.
For the primary mirror I’ve provided steps for both manual and laser alignment techniques.

  1. Position and align the secondary mirror

    First, checking and aligning the secondary mirror. This is the time-consuming part of carrying out full collimation. It should only need to be checked if experiencing poor image quality, after a knock to your scope or on a 12-18 month basis.

  2. Collimate the primary mirror (with a laser tool)

    Next, if you have a laser tool then follow this guide to quickly collimate the primary mirror.

  3. Manually collimate the primary mirror (without a laser tool)

    Finally, if you don’t have access to a laser tool, you can use a collimation cap.

Finishing up

Next – get out and enjoy your freshly collimated telescope! It’s worth performing a star test (“field collimation”) to help you further optimise your alignment.