Re: [ATM] Coulter Vs GSO mirrors

[Jarvis Krumbein <jkoptic@juno.com>]

I've been using a Coulter 13.1" mirror (from an old blue tube Coulter
DOB) for many years.  I built a new scope around this mirror after
testing the mirror as I couldn't manage the weight of the original.  The
mirror is excellent and passes all the star tests.  I've also seen some
very bad Coulter mirrors of about the same vintage.  If you can test the
mirror, do so and then make your decision.  I also assume that the price
on the Coulter mirror is considerably less than the GSO.  If this is the
case, I'd go for the Coulter unless it's got astigmatism problems.  You
can always refigure later if necessary but for normal visual observing it
will be OK.

Jarvis Krumbein

On Fri, 6 Oct 2006 08:49:23 +1000 "Corona Australis"
<corona_australis@westnet.com.au> writes:
> Hi Folks,
> 
> Looking for informed opinions. I have been churning over the
> idea of building my own dob style telescope. Using a 12" f/5
> mirror supplied from GSO. However there is a Coulter 13.1" f4.5 
> Pyrex mirror that has become available. I fully understand the
> dynamics of the two mirrors ie: focal length and diameter are
> different. I'm more interested in what wouldbe the better quality 
> made mirror of the two, or would the two be of similar quality.
> It's just that I have never heard anything of Coulter mirrors
> and what their reputation is like. 
> 
> Or maybe lets say to you experienced telescope builders, if you
> had to decide which mirror to use which one would you go for.
> The Coulter mirror had been stored for some years with the 3M 
> plastic protector still on it but has been removed and used 
> recently. Where as a mirror from GSO would be brand new.
> 
> any thoughts would be greatly appreciated
> 
> regards
> 
> Ozzy
> 
> PS: Yes I know I real telescope builder would probably make
> his/her own mirror. But I'm just not setup or skilled enough
> for that.
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> 
> 
 
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