A collimation cap for quick collimation of a Dobsonian telescope. Equipped with an additional overlay with a sight to make telescope alignment easier.

Short description of collimation using a collimation cap:

1. Place the telescope on a stable surface and point it at a bright, uniform area (e.g. a wall or the twilight sky).
2. Remove the eyepiece and insert the collimation cap into the focuser.
3. Looking through the hole in the cap, adjust the secondary mirror so that it appears centered in the focuser and evenly illuminates the primary mirror.
4. Next, using the center marker (e.g. a dot) on the primary mirror, adjust the primary mirror with the collimation screws until the marker is positioned exactly in the center of the view (on the sight axis).
5. Recheck the alignment — all elements should appear concentric.
6. Remove the collimation cap and insert the eyepiece — the telescope is ready for observation.

The additional sight overlay makes it easier to precisely align the optical axis and speeds up the entire process.

You can line the inner part of the collimation cap with aluminum foil to make the process easier.

If any part is too loose or too tight, you can adjust its diameter using the contour compensation option.