Re: ATM (no subject)

["James O'Malley" <omalleyj@eclipse.net>]

On Wed, 18 Aug 1999, Reed Alan Spaulding wrote:

> 
> 
> I'm building an eight inch scope and have been considering a modified
> hershlinian scope design.  I,ve never actually seen a scope of this
> design, so I'm wondering if there are some probloms associated with this
> design and if that is the reason why I haven't seen any telescopes of
> this design at Stellafane.  Thank you in advance for your responces.
> 
> 
I had read somewhere (R&vV?) that the easiest way to do this was to use a
spherical mirror with a long enough F ratio to still be diffraction
limited. You have to live with coma that is asymetric across the field if
you use an off-axis portion of a parabola. I *think* the limit for an 8"
was F/12 if you stay with a sphere. 
-------------------------------------------------------------------------------
Jim O'Malley    |
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