Re: ATM 4 tubes truss structure questions...

[Aplanatic@aol.com]

Hi Benoit:

> I saw the pictures at the Fairborn observatory
>  
>  See 
>  
>  http://schwab.tsuniv.edu/t4.html

This implementation has way too much diffraction for an imaging scope.  The 
idea behind the truss structure is to form triangles in both the x- and y- 
directions.  If the truss tubes do not enter the light path (highly 
recommended), and the truss structure has symmetry about the optical axis 
(not necessary but recommended) then the minimum number of truss tubes would 
be six, I believe.  I always use eight, out of personal preference.

Dave.