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19439Re: [William Optics] Re: Focuser Sag

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  • Ed
    Mar 2, 2009
      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 substantially greater.

      Just a thought..............

      Forever clear skies & great seeing!
      Cheers, Ed
      RASC - Calgary Centre
      POD Astro Dome Observatory
      N 51° 05' 10.06" W 113° 58' 22.24"

      ----- Original Message -----
      From: "Timm Bottoni" <t.bottoni@...>
      To: <William-Optics@yahoogroups.com>
      Sent: Monday, March 02, 2009 3:43 PM
      Subject: [William Optics] Re: Focuser Sag

      > Hi Greg,
      > Is there a way to eliminate a variable and actually measure what you
      > think is focuser sag? It may be that it is related to the Vixen
      > product. Perhaps it is really an alignment issue that is not visible
      > but this is just a guess.
      > It seems more likely to me that this might be the direction to look
      > since, the 66 and 90 WO scopes have completely different designs,
      > focal lengths, focuser designs, etc. If the two products act the
      > same, and the are so different, it would lead me think that the
      > problem lies somewhere else, since what is the probability that those
      > two completely different products would exhibit the exact same problem
      > with the Vixen, but not with each other. Maybe through process of
      > elimination and careful measuring you can figure out the root cause.
      > Hope it helps somehow. Give us more feedback when you can and we
      > will try to help while it's still cold out and we are too chicken to
      > go outside and freeze our butts off.
      > Timm
      > --- 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.
      > >
      > > Greg
      > >
      > ------------------------------------
      > www.williamoptics.com www.williamopticsracing.comYahoo!
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