Re: [ATM] Tough questions about Aperature Stops

["Bob May" <bobmay@nethere.com>]

The coma problem is fully in the primary.   Tilt it and you then
have a poorly collimated telescope.
The off-axis aperture masks merely decrease the amount of light
getting to the primary mirror of the telescope which can help
with aberrations that are built onto the surfaces of the mirrors.
The other thing is to decrease the size od the aberrations from
the seeing conditions so that a better view may be obtained.
Aperture masks for looking at bright on-axis objects do work and
do work well.
I'll also note that by putting a second and a third off-axis
aperture, you get a focusing device that works well as the two or
three telescopes that thus get made will only focus at one point
and that is when the images from those telescopes are focused at
the same point.
Bob May
bobmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
Replace the obvious words with the proper character.

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