Re: ATM stopping a newtonian.

[Hermit <klowther@cisnet.com>]

Sam Michael wrote:
> 
> Why is it that we do not stop the aperture of a newtonian to be the same
> size as the mirror.  If one has a 6" mirror in an 8" tube.  Shouldn't one
> stop the aperature at something much closer to 6"?
> 
> I am looking at baffeling a newtonian and am confused as to why the tube end
> is left large.  This would seem to allow off-axis light to enter the tube
> and hit the mirror...
> 
> I am sure I am going to kick myself when I hear the answer.
> 

Less thermal problem with a larger tube.  Also off axis light isn't
going to enter the eyepiece like in a cass or refractror.

-- 
Ken Lowther
Youngstown, Ohio
http://www.atmsite.org
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