Re: ATM Secondary Mirrors

[Steve Bell <sb635@delphi.com>]

Dave McCarter wrote:
> 
> 
> The other day I was out observing, and noticed while some one else was
> looking at the moon through my scope that a ring of light was passing
> around the diagonal mirror! This is a MEADE STARFINDER 10", and in the
> catalog the secondary is listed as 2.60 inches. I measured it when I got
> home, and found it was 2.25 inches. Mel, run that through your vignette
> program! Man am I steamed!
> 

This brings up another interesting question. Do the manufacturers of
fast Newtonians (Meade, Orion, etc.) offset their diagonals? I have it
by second-hand knowledge that the NGT 12.5", the fine scope put out by
JMI, does *not* have its diagonal offset. A person who I've exchanged
email with, who just recently purchased a NGT 12.5", asked them this
specific question. They said that they used to, but that they no longer
do. He didn't say why.

-- 
Clear skies,
Steve Bell
email: sb635@delphi.com
Astrophoto page: http://people.delphi.com/sb635