question on focusers

Hello folks

Hoping someone can educate me.

I am fairly new to astronomy and am considering buying a telescope with a 2" focuser. Does this present any problems using a 1.25" eyepiece? What are the relevent issues regarding the relative size of the focuser and the eyepiece?

Yours in ignorance

James

Hi james,
If the focuser is a permanenet one on the telescope tube, then you hav 2 choices:
1) You can use your existing 1.25" eyepieces with the 2" focuser, but you will have to get an adapter (2" down to 1.25") which your eyepieces sit in, in the focuser. Or
2) buy some new 2" eyepieces! ( www.andromedaoptics.com might be able to help)

Hope this is of some help!

Seanie.

I am fairly new to astronomy and am considering buying a telescope with a 2" focuser. Does this present any problems using a 1.25" eyepiece? What are the relevent issues regarding the relative size of the focuser and the eyepiece?
James

Absolutely no problems at all. Many refractors and indeed other types, come with 2" focusers. You can quite happily use a 2" focuser with a 1.25" diagonal and 1.25" eyepieces. It also gives you the option of using a 2" diagonal and 2" eyepieces. 2" diagonals normally come with a 1.25" adapter so you can use your 1.25" eyepieces as well, although this arrangement brings no extra benefits over a 1.25" diagonal.

Hope this explains what you asked.

Gordon

Hi,
As far as I can make out, there are really 2 reasons for going to a 2" focuser.

1, Alot of the wide field of view eyepieces are 2".

2, Photography/imaging, 35mm film photography is better done with a 2" barrel, it wont ge long from now when CCD cameras requiring 2" barrels will be (relatively) cheaply available (I hope).

I think its best to have a 2 inch focuser, this gives you the choice of using either 2" or 1.25" eyepieces instead of been stuck with one size, a choice is always better (adapters are easily available).

Sean, Gordon, Dave

Thanks for the sound advice.

James