Star-Testing the Telescope

Collimating Orion StarMax™ and Apex™ Maksutov-Cassegrain Telescopes

(StarMax 90,102, and 127, Apex 90, 102, and 127) (9821,9824,9826,9820,9823,9825)

Collimating is the process of aligning a telescope’s optics. Your StarMax or Apex’s primary mirror was aligned at the factory and should not need adjustment unless the telescope is handled roughly. This manual contains information on how to test the collimation of your telescope and instructions for proper alignment should that be needed.

Before you start adjusting the primary mirror of your tele- scope, make certain that it is actually out of collimation by performing a star test.

Take your telescope out at dusk and let it acclimate to the outside temperature; this usually takes 30-60 minutes. When it is dark, point the telescope upwards at a bright star and accurately center it in the eyepiece’s field of view. Slowly de-

Out of collimation	Collimated

Figure 1: A star test will determine if a telescope’s optics are properly collimated. An unfocused view of a bright star through the eyepiece should appear as illustrated on right if optics are perfectly collimated. If circle is unsymmetrical, as in illustration on left, scope needs collimation.

focus the image with the focusing knob. If the telescope is correctly collimated, the expanding disk should be a circle (Figure 1). If the image is unsymmetrical, the scope is out of collimation. Also, the dark shadow cast by the secondary mir- ror should appear in the very center of the out-of-focus circle, like the hole in a donut. If the “hole” appears off-center, the telescope is out of collimation.

If you try the star test but the bright star you have selected is not accurately centered in the eyepiece, the optics will always appear out of collimation, even though they may be perfectly aligned. It is critical to keep the star centered, so over time you will need to make slight corrections to the tele- scope’s position in order to account for the sky’s apparent motion.

Collimating the StarMax/Apex

To collimate your telescope, remove the diagonal and eye- piece and look into rear opening of the tube (also remove the dust cover from the front of the tube). This should be done indoors, with the telescope pointed at a white wall in a well- lit room. Try to keep your eye centered with respect to the rear opening of the tube as best as possible. Using an Orion Collimating Eyepiece will aid greatly in keeping your eye cen- tered and is strongly recommend.

Alternatively, you can make a crude collimating tool out of an empty, black plastic 35mm film canister. It will not have crosshairs, so it won’t be as precise, but it will be better than nothing. Cut 1/2" from the top lip of the canister and put a 1/16" to 1/8" diameter hole in the center of its bottom. Insert the film canister collimating tool into the focuser like an eye- piece with the bottom end out.

IN 183 Rev A 03/02