Re: [ATM] undercorrecting?

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

Ah, here comes another argument that will end up along the lines
of the Apodizing argument.
First off, when the mirror is in close equilibrium, the shape
will be the shape that it was supposedly made to and thus if you
do an undercorrected mirror then the mirror will be
undercorrected and not giving the optimum images.  What this all
means is that you have to then calculate how fast you want the
mirror to be coolong and keep it at that rate for the whole
night.
When you sit down and really look at the final results, unless
you are near the performance spec of the scope (high power to
where the Airy Disc is visible) the difference in viewing will
pretty much be invisible to the viewer of the image.  To a camera
(we won't even bother to discuss a film camera!), if the pixel
size is larger than the Airy Disc size, the difference in imaging
won't be really any different, especially if the focus isn't
perfect for a particular image.
I feel that if you want an undercorrected surface, you make it to
about 1/8th wave accurate but undercorrected and you will still
have a decently good scope no matter what happens.  If you really
want to have the "perfect" scope, you really shouldn'/t have
built a Newtonian scope in the first place!
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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