Re: [ATM] Fast primary unobstructed telescope

[Jarvis Krumbein <jkoptic@juno.com>]

Kevin, I don't think that there is any way you can have a totally
obstruction free system with this mirror but if you are willing to accept
a very small obstruction (for example 1") then a folded Gregorian is one
of the choices that you have.  You could also go for a Dall-Kirkham with
a small secondary and/or a transfer lens system of one sort or another
but I like the idea of the folded Gregorian.  You do intend to improve
the figure of the mirror don't you?  All the mentioned systems will
require either a parabolic or elliptical figure for the primary.

Jarvis Krumbein


On Mon, 29 Nov 2004 13:47:40 -0800 (PST) Kevin Whitefire
<chaosopher23@yahoo.com> writes:
> I have a primary that's 13.25" in diameter with f/D of
> 3.125, give or take a little.  Its exact ratio isn't
> closer than a quarter inch accuracy, using a solar
> focus on a white surface.  Its surface figure is
> smooth, slightly zonal, and hyperbolic in general.  So
> far, I have intent to use it as a Gregorian if I can't
> get an unobstructed design for it.
> 
> Is there an unobstructed telescope configuration that
> works with a fast primary like I have?  I don't care
> about the final f/D of the scope, but I want a visual
> system that can be used with common eyepieces.
> 
> Why am I doing this?  The same reason that causes
> people to climb mountains, the same reason that dogs
> chase cars.  They're there.  This problem is here.
> 
> A push in the right direction is all I need.
> 
> Kevin of Eastern Iowa
> Seeker of the Darkness
> 
> 
>                 
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