Starguide - A Practical Guide to Astro-Photography

Actual Step

Collimation Preparation

updated: 2024-05-04

Purpose

Prepare the collimation

Previous Step

Equipment Check

Next Step

Collimation Tools

Prep 1

Place the optical tube on a table or move the telescope to a horizontal position on the mount. It is helpful to point the telescope at a homogeneous bright surface (paper, house wall, ...). 

Now insert the collimator into the mount of your focuser. It is helpful to align the labeling with the collimation screws to make it easier. Gently press your hand against the back of the collimator. This will ensure that the collimator is optimally positioned in the focuser. Tighten the collimation screws slightly. 

WARNING: It is better not to touch the central locking screw on the second mirror, as this can cause the mirror to be completely out of alignment. 

However, if all 3 adjustment screws are very tight, the central locking screw can be loosened very gently with a Phillips screwdriver. However, it is always safer to loosen only one of the locking screws to allow the other two to move freely.

Prep 2

Remove all extension rings except for one 25 mm extension ring, install the focuser tilt adapter and the focuser at the end of the ring.

Prep 3

If possible remove the internal baffle on the main mirror that blocks obliquely incident light (this is possible e.g. on the TSO 203/1624 RC PRO)

Prep 4

Move the focuser out until the edge of the primary mirror is clearly visible in the reflection in the secondary mirror and is no longer obscured by the tube of the focuser.

Prep 5

Illuminate the scope: This is best achieved by placing a piece of white paper in front of the telescope at a distance of 10 cm so that the collimation screws of the secondary mirror can still be easily reached, and illuminating this paper screen from behind.

Prep 6

Have all the necessary tools ready 

> see next step Collimation Tools