To: atm{at}shore.net
From: Andy Saulietis 
Reply-To: Andy Saulietis 


Re 40" Nasmyth f-30:

You might want to consider the Mersenne variant of the Cassegrain
design..the secondary is made to produce a collimated beam which is then
refocused by a high quality small refractor..the f# is the same as that of
the refractor. Clyde Bone has made a 30" version of this..it's also a
Nasmyth with 2 folding flats on the elevation axis, the refractor swivels
up/down making the eyepiece accessible from even a wheelchair.

The refractor can have an annular low-x fov surrounding the main central
fov, from the sky surrounding the secondary mirror.

Disadvantages? 4 reflections, complex collimation, expense of a 5-6"
short fl Apo reimaging scope. Andy Saulietis
ISS Enterprises
PO Box 19
Mayhill NM 88339


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http://www.pvtnetworks.net/~iss/starend1.htm
505-687-3067 voice/fax, call voice or e-mail to set up e-mail: iss{at}pvtnetworks.net

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