Meade 16" Lightbridge questions

[George]

I finally got a Dob and my aperture fever is now under control.

Since I have at least one important question to ask, and this seems to be the first thread on this scope, I thought I'd list the questions (and links to answers) as they come in this OP (opening post) to serve as a reference for others.

1) Bright objects (e.g. Saturn) have an echo image very close to the original. Why?


Is it stray light due to the open truss tube?

[RickJ]

Certainly not due to the open truss. I've seen double images when I get careless and the seam from two lenses in my glasses bisects the exit pupil. One will be in focus, the other not.

Likely easily solved by an experienced amateur at the eyepiece but difficult from afar as I don't know how it behaves or what it looks like when the scope moves or the head moves the eye around the exit pupil. Sounds like some kind of internal reflection issue but that's only a guess. If you project the moon or better yet a 1st magnitude star (Vega) onto a sheet of white paper held up to the focuser (no eyepiece) does this form a second image. I would suspect not. If it does something very serious may be wrong with the optics. Rare but did see it once many many years ago.

Rick

[Tog]

I have a 16" sonotube Meade and I've never noticed this issue. Do you see it in all eyepieces? I'm wondering if the ring that holds the EP elements together might be loose enough that you've got an air pocket large enough to get an internal reflection in the EP itself. I have one that I have to tighten every now and then. I can usually tell when I pick it up because I can hear it rattle.

[George]

Thanks for the help!

I used only the 2" eyepiece supplied with the scope. This scope is at my father's little ranch and I had forgotten that the other eyepieces were elsewhere. I should be able to get back down there this week and try the other eyepieces.

It seems odd that I only notice the fuzzy secondary image for bright objects. The brightness level of this anomaly does seem to vary with eye angle into the eyepiece.

Also, the collimation seems to be holding nicely in spite of the jostling I give it when I haul it in the Gator. I did install a set of Bob's Knobs, which really helped me with my old 8" SCT since it requires regular adjustments.

The red dot finder supplied with it does not have the red ring feature, so I'm swapping it with one that does. [I have printed Messier charts with this ring superimposed for quick finding.]