Eyepiece tightness question.

[MaxBlancke]

Another dumb question.
While trying to set up my Nextron 8i, I noticed that my diagonal, barlow, and eyepieces were all pretty loose fits. Tightening the little set screws moved each component off center a little bit, and a bit out of parallel in some cases. That made it hard to set up and collimate properly.

To be more specific, I was able to wrap a .03" shim around each accessory, and they fit much better, or at least it does not bug me so much that way.

Is it normal to have such a loose fit, and if so, is there a reason for it?

[Lady Fraktor]

There should be a bit of free play between the different surfaces so nothing binds.
Manufacturing tolerances are not always as good as they should be either which is a problem.
I have a premium diagonal that I have to patiently work eyepieces into as the tolerances are to tight.
Getting eyepieces out is just as painful

[Bigzmey]

Unfortunately entry level accessories often come just with single set screw and loose tolerances which create off centering problems you have described.

The only way around is to upgrade the telescope visual back and diagonal to better quality which come with at least brass compression ring or better self-centering adaptor.

[gregl]

If you have the skills or know someone who does, you can drill and tap for additional setscrews so you'll have three equally spaced. Then tighten each equally until just tight enough. And I'd use nylon setscrews to reduce the chances of scoring the barrels of whatever you put in there.

[MaxBlancke]

Thanks for the replies. I ordered a visual back with a collet-type attachment. I am shopping a bit for a better diagonal, but am not yet up on the advantages of the various types.
Worst case, I can keep some strips of .03 shim material in my kit. If I had a lot more time to waste, I might put an internal groove, brass compression ring, and additional screw on my existing diagonal. However, it is a stock Celestron, and probably ought to be upgraded anyway.

[gregl]

Although you are on track to a solution, for others reading, Baader makes a series of eyepiece clamps and adaptors that look like they would solve the problem: https://www.baader-planetarium.com/en/a ... lamps.html