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While your NexStar telescope requires little maintenance, there are a few things to remember that will ensure your
telescope performs at its best.
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Occasionally, dust and/or moisture may build up on the lens of your telescope. Special care should be taken when
cleaning any instrument so as not to damage the optics.
If dust has built up on the optics, remove it with a brush (made of camel's hair) or a can of pressurized air. Spray at an
angle to the lens for approximately two to four seconds. Then, use an optical cleaning solution and white tissue paper to
remove any remaining debris. Apply the solution to the tissue and then apply the tissue paper to the lens. Low pressure
strokes should go from the center of the corrector to the outer portion. Do NOT rub in circles!
You can use a commercially made lens cleaner or mix your own. A good cleaning solution is isopropyl alcohol mixed
with distilled water. The solution should be 60% isopropyl alcohol and 40% distilled water. Or, liquid dish soap diluted
with water (a couple of drops per one quart of water) can be used.
To minimize the need to clean your telescope, replace all lens covers once you have finished using it. This will prevent
contaminants from entering the optical tube.
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The optical performance of your telescope is directly related to its collimation, that is the alignment of its optical system.
Your telescope was collimated at the factory after it was completely assembled. However, if the telescope is dropped or
jarred severely during transport, it may have to be collimated.
To check the collimation of your telescope you will need a light source. A bright star near the zenith is ideal since there is
a minimal amount of atmospheric distortion. Make sure that tracking is on so that you won't have to manually track the
star. Or, if you do not want to power up your telescope, you can use Polaris. Its position relative to the celestial pole
means that it moves very little thus eliminating the need to manually track it.
Before you begin the collimation process, be sure that your telescope is in thermal equilibrium with the surroundings.
Allow as much as 45 minutes for the telescope to reach equilibrium if you move it between large temperature extremes.
To verify collimation, view a star near the zenith. Use your high power eyepiece — 9mm focal length. It is important to
center a star in the center of the field to judge collimation.
the star. If you see a systematic skewing of the star to one side, then re-collimation is needed.
Figure 6-1 -- Even though the star pattern appears the same on both sides of focus, they are asymmetric. The
dark obstruction is skewed off to the left side of the diffraction pattern indicating poor collimation.
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Slowly cross in and out of focus and judge the symmetry of
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