Re: ATM another question

[UC007@aol.com]

In a message dated 97-09-21 22:17:30 EDT, atm@tiac.net writes:

<< It's possible to make a rotating cage, but I just live with the focuser 
 positions.  IMHO it's too difficult to make one that maintains collimation, 
 especially at f/4.5 like mine.  Besides, the CCD camera has to put up with
the 
 strange positions more often than I do these days :-)
 
                  - Matt Marulla
                The ATM Page
                http://www.tiac.net/users/atm
  >>

IMHO the only way to rotate the focuser and maintain collimation short of a
lot of very expensive machining of very expensive castings, is to rotate the
whole telescope in its mounting saddle. This arrangement is non critical in
so far as smoothness of bearings and concentricity is concerned. As long as
the tube itself is stiff enough, the relationship between mirror, secondary
and focuser remains unchanged. 

One other thought, be sure that balance weight positions remain in their
correct relationship to the whole assembly. Usually, this is not a problem if
the tube is balanced around its longitudinal axis as well as through the
saddle trunions or declination axis as appropriate.

Good luck,
Bill Fries