Re: [ATM] Rotating the OTA

["Donald Good" <donald.good@comcast.net>]

Ken,
I also suggested to Larry off list something similar to your suggestion, the
Mersenne Nasmyth a la Clyde Bone, which has been posted before:
http://astro.umsystem.edu/atm/ARCHIVES/NOV96/msg00524.html
For a picture, see:
http://www.rtmcastronomyexpo.org/archives/photos/94RTMC06.jpg

A relay lens in the light path between the parabolic secondary and the
Nasmyth diagonal keeps down the size of the secondary obstruction and may
allow opportunities for optical corrections.

For more information, search the archives http://astro.umsystem.edu/atm/ for
"Mersenne"

While the Springfield mount is great for its stationary eyepiece and
equatorial tracking, it usually has to have a permanent pedestal mounting, a
proportionaly larger diagonal, an odd counterweight, and a high viewing
position (around 80% of the FL) so it does not scale well to larger
apertures.

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Ken Hunter
Sent: Monday, January 01, 2007 5:32 PM
To: Mel Bartels; atm@atmlist.net
Subject: Re: [ATM] Rotating the OTA

I know Larry personally and suggested (off-list) that he consider a fork
mounted Newtonian on an Az-El mount with the eyepiece co-axial to the
elevation axis. This way he can wheel his chair around the mount and the
eyepiece height will be non-changing. He can use a tube that is twice the
length of the normal Newtonian with some compensating weight at the skyward
end for balance or keep the short tube and insert a tertiary mirror near the
primary to shoot the photons out the side thru the Elevation trunion.
   
  Ken Hunter
   

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