Debbie, remember that the star-test is just for "tweaking". The telescope should be at least eyeball-collimated first, and not grossly misaligned. Never collimate with a diagonal, or you could be compensating for misalignments in the diagonal, unless it is known with certainty that the diagonal is perfectly aligned. Most are not. You will need to wait for good seeing- high power is needed to see the diffraction rings large enough to interpret them. Depending on the size of your scope, Polaris may be too bright, but give it a try. I'd go for something a little higher, personally...less air to look through. I have "star-tested" using an artificial star years ago. I hung a silver Christmas-tree ball on a telephone pole, and aimed a mini-mag flashlight at it with a cover with a small hole in it. You need to be at least a hundred yards (more is better) from the artificial "star". Richard Berry also had an article in S&T on an easily-made artificial star some years ago. This way you can do the procedure without having to track, and not having to have clear skies. You still need relatively calm air along the optical path, however. Finally, make sure you have a reference. Dick Suiter's book "Star-Testing Astronomical Telescopes" is excellent, with computer-generated diffraction patterns representing just about any optical problem likekly to be encountered. While aimed primarily at the fabricator, there is much useful stuff on collimation. Don't just turn screws randomly. If the diffraction pattern looks symmetrical, you're collimated. If it isn't, and turning the screws doesn't improve it, the problem may not be mis-collimation at all. Good luck, hope this helps. Chuck --- UTAHDEB@aol.com wrote:

Chuck

That makes sense. I should collimate on Polaris during good seeing? What kind of diagonal should I use if any at all?

Debbie

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