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19060Re: Linear Focuser

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  • James M. Postle, Sr.
    Dec 1, 2008
    • 0 Attachment
      I am very happy to see the Linear Focuser come to market.

      MSS's FF-2 was a gift to the market which fit on a Rack and Pinion
      (R&P) Focuser. This in comparison with the "Ball Bearing" ratio
      units. I have taken the Orion 100ED focuser's Roller Plates (2)
      merged them into a Celestron 150 Focuser. There is "NO" "Draw Tube"
      slop.

      Now, if someone would continue on with the FF-2 (Gear Driven) and
      merge a Linear Focuser then the telescope world would be a far better
      place. Meaning, I would buy one.

      With my personal use, I have never found any problems with backlash.
      This, as having gear drives in two places. And... Using a properly
      made Telescope R&P Focuser I believe problems with backlash to be a
      myth. As such, I feel a R&P Focuser and the Mercury FF-2 to be of the
      finest designed Focuser I own. Superior to the Crayford Standard.

      So, currently, the Linear Focuser is of limited use of which I would
      like to see expanded.

      Postle



      --- In William-Optics@yahoogroups.com, "aruangra" <aruangra@...>
      wrote:
      >
      > Hi Timm
      >
      > Many thanks for the clear description. I am excitedly waiting for
      > Megrez 90 with the new linear power focuser.
      >
      > Regards,
      > Anat
      >
      >
      > --- In William-Optics@yahoogroups.com, "Timm Bottoni" <t.bottoni@>
      > wrote:
      > >
      > > Hi Anat,
      > >
      > > Yes, sort of like a rack and pinion, it has a steel rack and a
      nylon
      > > gear that turns with the focuser knobs, but it is different in
      several
      > > ways, more sophisticated compared to the rack and pinions
      focusers I
      > > have seen before because the entire weight rides on a steel bar
      with
      > > steel ball bearings at all times on both sides of the steel
      bar.
      > >
      > > Both ends are held in place by three inset screws, so the 2"
      piece is
      > > not threaded.
      > >
      > > The SCT threads screw onto the back of the C8 directly, and that
      is
      > > the silver part you see in pictures. That part is not threaded
      onto
      > > the rest of the focuser. There are three inset screws that hold
      it in
      > > place in a channel that allows it to rotate, and these three
      screws
      > > are adjustable for tension of the rotation. The focuser is
      locked in
      > > place by a thumbscrew.
      > >
      > > The end where the diagonal inserts also has three screws that
      allow
      > > the end piece to also rotate, but there is no thumb screw, it is
      held
      > > in place and tightened to the tapered flange by the three inset
      > > screws. WO stated that a custom adapter could be made to attach to
      > > this, but I have not seen any more info on what that might be.
      > >
      > > Another nice improvement is the dual set screws on the brass
      retaining
      > > ring, rather than only one like my refractor has.
      > >
      > > Does that answer your questions?
      > >
      > > Take care,
      > >
      > > Timm
      > >
      > > --- In William-Optics@yahoogroups.com, "aruangra" <aruangra@>
      wrote:
      > > >
      > > > Dear Timm
      > > >
      > > > Thanks for your review. So it is a rack and pinion focuser.
      Right?
      > > > I see that the 2" adapter can be unscrewed from the 2.5" tube.
      Could
      > > > you tell me the thread size of the 2.5" tube? The thread is very
      > > > useful to rigidly fix a camera and accessories with a proper
      adapter.
      > > >
      > > > Best regards,
      > > > Anat
      > > >
      > > >
      > > >
      > > >
      > > > --- In William-Optics@yahoogroups.com, "Timm Bottoni"
      <t.bottoni@>
      > > > wrote:
      > > > >
      > > > > Hi William,
      > > > >
      > > > > I'll try and explain it without picturesf for now, but will
      include
      > > > > pictures and details in my upcoming review.
      > > > >
      > > > > First - DON'T TAKE IT APART if you have one, trust me, I
      know. ;-)
      > > > >
      > > > > The Linear Power focuser uses a rack and pinion design to
      move the
      > > > > focuser forward and back, which is very different from any
      other
      > > > > focuser I have seen. The entire focuser tube runs on a steel
      rail
      > > > > that is sandwiched between two sets of ball bearings. I am
      not sure
      > > > > how the two speed focuser works, if it is on tension or gears,
      > but it
      > > > > is incredibly smooth.
      > > > >
      > > > > The tension is adjusted easily using an allen wrench, and is
      > locked in
      > > > > place using a thumb screw. The ability to adjust the tension
      > is very
      > > > > forgiving, and allows for easy adjustment to meet your weight
      > > > > requirements.
      > > > >
      > > > > I have never used a FeatherTouch or other brand of crayford
      or rack
      > > > > and pinion, but this design allows for the travel to stay
      incredibly
      > > > > smooth at any tension from too loose to too tight.
      > > > >
      > > > > It is a 2.5" design, and the thread on the SCT end, and the
      > inside of
      > > > > the draw tube is 2" internal. Everything is ultra flat black
      > inside,
      > > > > and the SCT is shorter in it's travel than the refractor ones
      I see
      > > > > pictured on the WO site, which makes sense since the travel
      tube
      > must
      > > > > stop at the threaded SCT ring, it can't go inside the back
      like a
      > > > > refractor one could.
      > > > >
      > > > > Based on my testing so far, this design is excellent and
      capable of
      > > > > handling a much heavier load than the Crayford design of the
      one
      > on my
      > > > > Megrez 80FD. If WO has a way to make it work on the ZS110,
      I think
      > > > > it will probably preform very nicely.
      > > > >
      > > > > I'll post the pictures and full review in the next couple of
      weeks.
      > > > >
      > > > > Timm
      > > > >
      > > > >
      > > > > --- In William-Optics@yahoogroups.com, "William Roy Penney"
      > > > > <penneywilliam@> wrote:
      > > > > >
      > > > > >
      > > > > > Hi Tim,
      > > > > >
      > > > > > Do you or anyone else have any details or information about
      > the new
      > > > > > linear focuser? Is it another crayford type or rack and
      pinion?
      > > > > > I would like to replace the focusser on my Z110, and maybe
      the
      > > linear
      > > > > > focuser is the "beefed up focuser" which was supposed to be
      > > available
      > > > > > soon from WO (several years ago) but did not eventuate.
      > > > > >
      > > > > > Merry Xmas
      > > > > >
      > > > > > William
      > > > > >
      > > > >
      > > >
      > >
      >
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