You want to collimate your Newtonian telescope to get the best possible image out of it and need a collimation aid that is precise but inexpensive.
Long metal tube with crosshairs
The collimation eyepiece is simple but absolutely effective. With practice, you will be able to collimate your Newtonian telescope in just a few minutes - especially if simply finely collimating your telescope for optimal imaging. The eyepiece consists of a long metal tube, a reticule and a 45° base. The reticule gives you the orientation required for the optical axis.
Collimation of refracting telescopes
If you use the eyepiece for checking the collimation of a refracting (lens) telescope, then you will see as many reflections as there are lenses in the telescope. If all the reflections are round and centred, then your telescope is well collimated.
