Eyepiece not focusing

ArcaneMagik (Craig) · #1 08-05-2010, 09:19 AM

I bought a new eyepiece for my telescope yesterday, and while using it last night I quickly found out I could not draw the focuser back enough to get it properly focused. The eyepiece is a Tele Vue Radian 8mm, and my scope is one of the Bintel 8" dobs.

Pulling the eyepiece slightly out and locking it in maybe an extra 5-10mm out of the focuser brought everything into focus. Can't remember how much I needed to pull it out as it was dark cold and I was too busy trying to get some use from the eyepiece.

I have done some quick searches and can't find anything related to the eyepiece and this kind of trouble.

Is there something I have missed with this? Is it a simple case of my scope's mirror alignment being out? What should I check next?

I am going to try it again tonight and play around with it some more.

I am loving the eyepiece despite this. Even with terrible viewing of Saturn (would not stay still!), it was a beautifully wide scene and a lot easier to find targets at high magnification compared to the 9mm plossl.

Robh (Rob) · #2 08-05-2010, 10:22 AM

Craig,

There is nothing wrong with your scope.
I had the same problem with some Tele Vue EPs I bought last year. I think the focal point of the EPs must be further up the barrel of the EPs.
I solved the problem by buying a 35mm extension tube (for a price estimate, BINTEL has them for $39).

Regards, Rob.

ArcaneMagik (Craig) · #3 08-05-2010, 10:39 AM

Awesome. Thanks Rob. Will drive over there today.

mswhin63 (Malcolm) · #4 08-05-2010, 10:42 AM

For some reason some eyepieces don't seem to work, I purchaced a Seibert 28mm and found the same problem.

Rob thanks for the suggestion I believe the eyepiece is good just that issue. I believe in mine I need a sleeve to extend out of the focuser, the extention ring on mine would still slide all the way through the focuser.