Re: [ATM] determining secondary size and fully illuminated field

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

ONe of the things to remember here is that the light falloff
isn't all that bad in reality.  For a wide low power view, you
may see faint stars pop into view at some point in the eyepiece.
Edtended objects will tend to be darker at the edges than you'd
expect.  You really need to convert the percentage values into
magnitude differences to see how they affect the view.  For high
power views, you'll only be seeing the central part of the FOV
anyway and that is the 100 percent part of the FOV so you won't
be able to tell any difference in the amount of light getting to
your eye.
I'll also note that on a Newtonian telescope, the outer parts of
the FOV will have comtic images and the aberration is caused by
the edges of the mirror not being the right shape for tthe
off-axis image so a bit of deletion of that part of the image
won't really affect the image as much as you'd think as most of
that light is spewed out into the tail of the camaticc image
anyway
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net


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