Quote:

---

Hello Fellows,I'm no expert but on Amart a fellow had trouble with halo of light around planets etc. with an Orion 102 Mak and they told him to stop down aperture with 1/4 inch to 1/2 inch mask to test for turned edge.Something to try.But then if you are happy with the Mak why bother.Cheers.
Steve M

---

The mirrors on Orion's Maks are undersized, i.e. the light that passes through the edges of the corrector lens misses the edge of the mirror. A 1/2" wide annulus around the front of the corrector would only eliminate the very edge of the primary mirror (if it is the cause).

I've thought about it, and I think two things may be happening:
1) the light bent outward by the outer edge of the corrector may be reflecting from the side of the tube into the light path. This would be more severe the farther off-axis the image was, which seems to be the case.
2) There is inadequate front-end baffling of lateral light coming into the scope.

#1 could be solved (with some difficulty) by flocking the inside of the tube and outside of the primary baffle.

#2 could be solved with a dewshield of 6" length that is very unreflective internally.

Alternatively, the corrector might be filthy and scattering light. The eyepiece may be dirty and doing the same.

But I'd bet on light scatter in the tube, simply because I saw such a huge difference when I flocked my SCT, which doesn't cause the entering light to diverge as much as a Mak.

--------------------
Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie

Post Extras