Re: [ATM] considering different design

[Jarvis Krumbein <jkoptic@juno.com>]

I was able to use the Porter Turret Scope right after it had been
refurbished many years ago (probably about 40 more or less).  The
original 16" plate glass primary  had been replaced by a fine 12" Pyrex
mirror.  The performance was excellent with an incredibly dark
background.  M13 looked better in the Turret than it did through a
particularly fine 16" from the Montclair NJ club which I believe took
first in optical excellence at that particular Stellafane.

Jarvis Krumbein

On Sun, 9 Jan 2005 10:30:00 -0800 (GMT-08:00) jeffmorgan@mindspring.com
writes:
> What is the optical performance of the Porter scope? Seems given the 
> location and fame of this scope quite a few people would have looked 
> through it. The only references I've seen to it were mentions by 
> Walter Scott Houston in his column. IIRC, the mentions were all 
> favorable particularly in terms of contrast.
> 
> -----Original Message-----
> From: Bob May <bobmay@nethere.com>
> Sent: Jan 8, 2005 2:31 PM
> To: atm@atmlist.net
> Subject: Re: [ATM] considering different design
> 
> Odd that nobody has mentioned that the Porter Turret Telescope at 
> Stellafane
> is the same design.  A flat on the dome reflects the sky to the 
> paraboloid
> mirror out at the end of the long truss which reflects it back to 
> the center
> of the flat where the light passes through a hole into the dome 
> where the
> eyepiece is mounted.  Very nice for the northern climates where snow 
> is more
> prevelant on the ground than that funny green stuff as the observer 
> is
> inside where it can be warm without any heat getting out to disturb 
> the air
> outside.
> Bob May
> bobmay@nethere.com
> http://nav.to/bobmay
> http://bobmay.astronomy.net
> 
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