Re: [ATM] 1.25in Versus 2inch focuser.

[James Crombie <jamescrombie@jamescrombie.com>]

Marco

I would go with a 2" focuser just to keep my options open in terms of 
eyepeices.  Just think of having to turn down a neibour at a star party 
who wants to try all of his Naglers on your scope :-)
  I would personally recommend the Starlights Instruments, Feathertouch 
focuser.  I put one on my 15" and as a machinist and an ATMer think its 
one of the best out there.

James Crombie
http://www.jamescrombie.com

Marco wrote:

>Which should I consider for the following scope:
>
>20in F5 mirror. I ran SEC and consulted my local mirror
>supplier and 83mm (3.27in) seems to be the best match
>in both Kriege/Berry's book and in SEC.
>
>However in Berry's book it is recommended that in a scope of this
>size, parameters give a practical limt of around 0.5 degrees FOV.
>
>Doing some calculation tells me that I only need a 1.25in focuser
>as a 24mm panoptic will supply me with a field of around 39 arcmin
>which is more than ample.
>
>My question is, what advantage would I get from fitting a 2in focuser if
>the 1.25inch eyepiece gives me my maximum practical field of view.?
>
>For that matter, is there any point in fitting a 2in focuser to anything F5 
>or faster?
>
>any illuminating ideas?!!
>
>Marco. 
>
>_______________________________________________
>ATM mailing list http://www.atmlist.net/
>
>
>  
>
_______________________________________________
ATM mailing list http://www.atmlist.net/