An odd eyepiece problem..

[DustInMyEyes]

I was able to pick up some used eyepieces today, but have come across an odd problem. I think it is probably just user error, but wanted to post as I genuinely can't figure this out.

I picked up the following Sirius Plossl pieces: 10mm, 17mm, 26mm, and 35mm. When I came home I wanted to give them a spin and make sure they work. The 10 & 17 fit just fine, but the 26 and 35 won't insert in the EP holder. These are from the same set and are the same sizes, they just BARELY don't squeeze by. Any thoughts on why this be?

[Islander]

Have you made sure that the EP retaining screw in the holder is fully unscrewed?

[NGC 1502]

One thing to check - If the 10 & 17 fit ok but the others won't, maybe they have been dropped and put the chrome barrels out of round ?

A close examination should show if this is the case. One solution perhaps, is to wrap the chrome barrels with tape, then VERY carefully try squeezing them back

into round using a vice. Use caution and check frequently by trying to see if they fit.

Regards, Ed.

[DustInMyEyes]

Thank you for your replies.

Islander--yes, that was my first thought. I verified it wasn't being blocked by the screws.

Ed--thanks for the idea. I am looking at it now and it doesn't appear to be off in that way, but if I get to a "nothing to lose" point this may be the direction I need to head. It really doesn't look any different than the others, though. Such an odd problem...

[glowjet]

If the barrels do not look damaged in any way and appear round, you may need to check with a vernier or a 1"-2" micrometer, as they could be ever so slightly oversize by just a few thousandths of an inch. Your only recourse then is to lightly emery cloth the barrels down till they fit after first protecting the glass elements in some way or another. I think this problem has arisen before with different makes of ep`s

John

[DustInMyEyes]

If the barrels do not look damaged in any way and appear round, you may need to check with a vernier or a 1"-2" micrometer, as they could be ever so slightly oversize by just a few thousandths of an inch. Your only recourse then is to lightly emery cloth the barrels down till they fit after first protecting the glass elements in some way or another. I think this problem has arisen before with different makes of ep`s

John

An excellent idea, thank you! It really shouldn't need much shaved off. Would the glass be protected if I ensure I'm holding the piece completely vertically and wipe excess metal downwards? Thanks again for the tip.

[nightfisher]

Another thing to try, get some different barrels of cheap ep`s

[Adrian]

I have one eyepiece that wouldn't fit into my barlow, although it fit in the focusser. On careful examination I found that the barrel had a slightly fat bottom edge (a lip, sort of) that was stopping it. I couldn't really see it, but I could feel it. I ground it down with a dremel &, although not pretty, it fits now.

Worth checking for this, though?