Re: [ATM] design question

[Michael Lindner <mikell@optonline.net>]

On Tue September 13 2005 3:00 pm, Kevin Williams wrote:
> the scope has a 2" focuser, and I use an adapter to use my 1 1/4 eyepieces,
> I took off the adapter, and moved the eyepiece into the hole by holding it,
> and I could focus, I estimate I had to hold the eyepiece 1/2" lower then
> the focuser top (fully racked in) get it to focus
>
> 2 questions
> what did I do wrong?

Perhaps nothing. If you bought a mirror, it's possible that the actual focal 
length is slightly different from the "nominal" focal length.

> how much and which way do I need to move the  primary mirror? or something
> else?

Since the eyepeices have to be moved *closer* to the mirror to focus, to fix 
it you move the mirror closer to the focuser. If you moved the mirror forward 
1/2" then that eyepiece would come to focus with the focuser all the way in, 
so you should move it up an addition 1/2" or so. You might want to try all 
your eyepieces and see where they focus relative to each other to make sure 
the new position of your primary will allow all of them to focus in the 
focuser's range.

clear skies
-- 
Michael Lindner
http://www.starastronomy.org *** http://home.att.net/~mikel
http://www.atmsite.org *** http://www.atmlist.net
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