Re: SV: ATM 18" f4.6 with a 2.6" diagonal

[spooner@page.az.net (Michael Spooner)]

Richard Schwartz wrote:
> 
> > A smaller diagonal will not lower coma-
> 
> I think  you are wrong about this.  A small enough diagonal will prevent
> light from the edge of the primary from reaching the focal plane.  This
> is the area that contributes the most to coma.  You can get the same
> effect by using a smaller mirror.  In fact, a small diagonal can cure
> turned down edge!

And using a large enough one, ALL wavefront errors will be unnoticeable.
                >^)