Simple Collimation Tool for Newtonian Telescopes
This collimation cap is a practical aid when collimating a Newtonian telescope. In the absence of a more intricate collimation tool like a Chesire eyepiece or a laser collimator this simple tool can be a great help in finding proper collimation for your Newtonian telescope. Just insert it in the 1.25" focuser and look through the small hole in the center. Now you can do the alignment without accidentally moving your eyes off the center of the focuser, which would result in bad alignment. You only need to center the secondary, the primary, the reflection of the secondary on the primary and the reflection of the collimation cap on the secondary. As soon as everything is concentric the telescope is properly collimated.
If you own a laser collimator the collimation cap helps you center the secondary in front of the focuser - something that couldn't be done with the laser alone.
Provides a centric view and thus a good adjustment in Newtonian telescopes