Re: ATM 16" F/33 valid design?

[Joe Mayenschein <mayen1@mwt.net>]

Hi Frank,

Do you have that issue of S&T?  I have a copy of the article and the secondary
is a sphere just a plain old edmund type of lens.  Granted f-70 I also think is
crazy,  but As I wondered how "Fast" you could go,, or just for thoughts,, I
wonder what the raytrace said about his original scope. The pic of saturn
looked pretty good.

Joe

Frank Ward wrote:

> Joe, You ask
>
> >See with that say 10" f-6 primary,  how "Fast"
> >you could make it with simple "Edmund" Specials lenses used as the convex
> >secondaries (spherical of course)  how fast (low of a f- ratio) can it go
> before
> >undesirable image degradation occurs.
>
> The only problem I have with this idea is the fact that no telescope I know
> of
> uses a parabolic primary and a spherical secondary.  No matter what the
> focal
> length you won't get a focused image. I know I'm wrong in a lot of
> conceptual
> optics but thats pretty basic. Now, if you had a prolate ellipsoid
> primary.......
>
> Best wishes,
>
> Frank Ward
> Atlanta, GA