Artificial Star
Collimation, in its simplest terms, is the alignment of the mirrors or other optical surfaces in the telescope. A telescope that is out of collimation will typically not perform as well as a lesser telescope (25-50% less aperture) that is in collimation. If you put the extra money into a larger telescope, you are not reaping any benefits of it unless the scope is collimated. Also, no telescope will allow you to reach a crisp focus at the high power end unless collimation is perfect. It is well worth the time and effort.
The star can be mounted on a table, or attached to a standard photo tripod using the ¼-20 adaptor provided on the bottom of the unit.
These can be used at star parties to provide a star for everyone. It never moves, so there are no tracking or centering issues to worry about. It is unaffected by atmospheric disturbances so you can get an accurate collimation under any seeing conditions.
The placement of the star depends on the telescope. For an 8" SCT we recommend approximately 100 feet. The further away from the scope, the better until you start loosing contrast in the eyepiece. Indoor use is a possibility although it is recommend collimation with the scope in position.
The procedure for collimating your particular telescope should be outlined in its manual. Please read the instructions there first. It will tell you the location of the collimation screws and any cautionary notes concerning collimation adjustments.
Our expert comment:
The artificial star is the best method for adjusting optics with a folded beam path. It is ideal for Cassegrain, SC, RC, ACF, Edge-HD and Maksutov telescopes.
Newtonian telescopes and short refractors require extension tubes to focus the artificial stars. The length of the sleeves varies depending on the instruments and the distance of the artificial star. Suitable sleeves for 2-inch focusers are available under the product numbers: 4575, 4576 and 4574.
Suitable sleeves for 1.25 inch focusers are available under: 6840, 12053, 14075 and 22009.
(Bernd Gährken)