This thread was started merely to gather information on the green laser as a star-pointer, Don, but I agree with you completely. Manual collimation, with a star-test for tweaking is the best way to go, but many folks either can't get the knack or don't want to take the time. Some just like gadgets. The collimators that project a grid are a step in the right direction. Rich and I used one on my 10" last year, and while it was close, a star-test later revealed that collimation was in fact off by about 1/10" at the image plane. While this may be satisfactory for visual use at low to medium powers, it is totally unacceptable for a "fast" Dob, imaging of any kind, or high-magnification viewing. Chuck --- "Don J. Colton" <djcolton@piol.com> wrote:
In my experience I have found lasers worse than useless for collimating Newtonians. See the June 2002 issue of Sky and Telescope for an explanation of the problems. As a test I set up a Newtonian telescope with the diagonal offset almost an inch in the wrong direction and by tilting the diagonal and adjusting the main mirror the laser converged as it is supposed to do; but the star images were terrible. A sight tube, Chesire and autocollimator are far superior for collimation.
Several times I have seen laser collimated telescopes that were dramatically out of collimation with shadow of the secondary far off to one side.
I have not tried the new holographic lasers that project a pattern so I can't comment on them.
Clear Skies Don Colton
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