> Subject: (ATM) off-axis paraboloid mirrors
> Can anyone give me any solid information about how good/bad these things are
> for building an unobstructed scope? My gut feeling is that they'd have more
> abberation -- probably coma -- than a symmetrical paraboloidal mirror of the
> same diameter and focal length, but how much more, and what kind?
(I'm responding because I haven't seen anyone else respond.) I think you're correct, since it's a peripheral piece of a large short f/# paraboloid. Of course, since it's a small piece its aberrations aren't as bad as the large paraboloid. I can do a reasonable approximate calculation, or a more tedious but exact third-order calculation. I'll let you know what I find.
Clay Spence cspence@sarnoff.com