Meade 152ED Alignment question

Hi All,

I bought a Digitec star collimator and Artificial Star to help me
align my Meade 152ED.

I find that I get a nice set of diffraction rings in one direction
and a fuzzy blob in the other direction. Does anyone know why this
would be? Is this something that I can correct?

Thanks
Don

Hi Don,

After reading your profile (too many telescopes, too little time) I would suggest acquiring a copy of H.R. Suiter's book Star Testing Astronomical Telescopes, which should have the answers you need. Assuming your diffraction rings are concentric, your unbalance could be caused by spherical aberration. It certainly doesn't sound good.

Milt

It sounds like spherical aberration, but it might simply
be caused by having the artificial star too close to the
scope. You want it at least 200 feet away to check
the spherical.

Hi Don.

Try this link:

http://voltaire.csun.edu/roland/startest1.html

Henrik