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question on focusers

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question on focusers was created by jfa15ie

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
18 years 5 months ago #1299

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Replied by Seanie_Morris on topic Re: question on focusers

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.
Midlands Astronomy Club.
Radio Presenter (Midlands 103), Space Enthusiast, Astronomy Outreach Co-ordinator.
Former IFAS Chairperson and Secretary.
18 years 5 months ago #1304

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Replied by gnason on topic Re: question on focusers

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
Gordon

SDAS

Stargazer am I
It seems that I was born
to chart the evening sky

Mark Knopfler - Sailing to Philadelphia
18 years 5 months ago #1305

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Replied by dave_lillis on topic Re: question on focusers

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).
Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor
18 years 5 months ago #1313

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Replied by jfa15ie on topic Re: question on focusers

Sean, Gordon, Dave

Thanks for the sound advice.

James
18 years 5 months ago #1367

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