19436Re: Focuser Sag
- Mar 3, 2009Greg,
Have you thoroughly examined your mounting of the 66 or 90 on
the Vixen looking for mount flexure? As you have the same issue with
the 66 and 90 together to a much, much lesser degree; I'm thinking
that the difference between the optical axes of the scopes is what is
behind the varying drift. The difference between the refractors is
quite small. But between the Vixen and either of the WO scopes is
Just a thought..............
Forever clear skies & great seeing!
RASC - Calgary Centre
POD Astro Dome Observatory
N 51° 05' 10.06" W 113° 58' 22.24"
--- In William-Optics@yahoogroups.com, "Greg" <gbenecke1@...> wrote:
> I have both a Mergrez 90 and Zenithstar 66 SD that I use both as
imaging scopes and guide
> scopes with each other and with a Vixen R200SS Newt. I notice that
when mated with the
> R200SS as guide scopes there is an appreciable drift in the guiding
that I attribute to the WO
> focusers. The R200SS has a Moonlite focuser on it that is rock
solid, so any drift I think is
> from flexure in the focusers of the WO scopes. Interestingly when
the WO scopes are used
> with each other the drift is almost nil. I think this is because
they sag in a similar fashion.
> Does anyone have any thoughts on how to fight the battle of the
sag? I have taken apart and
> tightened and adjusted everything in the focusers and made some
improvement, but some
> flex still remains. I have looked at replacing the focusers with
something like the Moonlite,
> but one copy would cost as much or more than I paid for the 66.
> I have been entertaining drilling and tapping holes for set screws
to lock down the tubes but
> there goes the resale value if I ever want to sell them. Any
thoughts are appreciated.
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