odd optics

I am perplexed. My very old Meade LX 8" sees double. I am using this scope to learn astrophotography here in Costa Rica. But.... focusing has been disappointing even with a Hartmann mask.

The doubling problem is easily detected when looking at Saturn. The edge-on rings are distinctly double on either side of "focus". And when focused, Saturn is blurred.

The mirrors have been recoated some years ago by the previous owner. He did the work and this is not recommended by Meade. I do not know if this may have caused the problem.

I have repeatably coliminated this scope at high power but the double image persists. Different eyepieces are no improvement.

Does anyone have a suggestion which may fix this problem?

Thanks for any help

Dan Fender

The coating (regardless of who did it) is not the problem, but rather the optical surface of the mirror is not a true & smooth parabola. It is *stepped* with the outer zone & central zone each coming to focus at a slightly different place. This mirror was a Dud from day one & refiguring (or replacement) is the only solution. I've run into this same situation while making & testing my own mirrors. Meade is primarily an Importer/rebrander (always was) plus the people in their Customer Service Dept do not make mirrors so that is why they could not properly advise you on this issue.

There have been threads before regarding double images in Newts. It was agreed that the most likely cause was due to different path lengths in the scope caused by thermal layers in the tube. That is pretty much the only thing that can cause multiple images. A poorly finished mirror will smear the image but not create distinctive multiple images.

I have seen double images in more than one Newt but I have no experience with SCTs.

good luck,
dan