RE: [APML] Photographic test of Meade 8" f/4 Schmidt-Newton

[Walter Koprolin <a9125657@unet.univie.ac.at>]

> > The use of a spherical mirror makes the optical
> > system coma-free, one of the advantages of a
> > Schmidt camera.
>
> That would be true if the corrector were at the
> radius of curvature, as it is in a Schmidt camera.
> With the corrector of a Schmidt-Newtonian actually
> within than the focal distance, the system is
> unfortunately neither free of coma nor free of
> spherical aberration (Schmidt cameras are free of
> both), according to Rutten and van Venrooij. But
> the coma is much better than with a standard
> Newtonian design.

I stand corrected, you are right there.

  Walter Koprolin
  http://www.astro.univie.ac.at/~koprolin/

_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo