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19097Re: Linear Focuser

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  • gjcaunter
    Dec 9, 2008
    • 0 Attachment
      Hi Timm,

      Thanks for the reply. As I said the center allen screw, if it is
      present, is obscured by a quality control sticker. Pressing the
      sticker in creates a dimple revealing the hole. I can't tell if
      there's a screw in it without removing the sticker. Maybe I should
      just whip it off and hope it goes back on.

      As for the thumb screw, unless I'm going mad there is no evidence of
      it. I don't recall ever seeing it either attached or loose in the
      case. If it had been screwed into the bottom at any point there's a
      chance it would have left a depression in the case foam, but there is
      none.

      Looking at the FLT98 the situation is the same as with the 2.5" SCT
      focuser on the same site. The FLT98 also has two extra thumb screws
      either side of the central rotation lock on top - again, I have the
      holes but mine have little black slotted screws in them.

      Seems odd that tension adjustment would be omitted. I think I'll query
      William Optics about this in any case. It will still be interesting to
      hear what others discover about the Megrez 90 focuser.

      Thanks again,
      Gareth

      --- In William-Optics@yahoogroups.com, "Timm Bottoni" <t.bottoni@...>
      wrote:
      >
      > Hi Gareth,
      >
      > Take a look at the picture on the WO website of the underside of the
      > focuser on the WO FLT98CF and see if yours looks the same...
      > http://www.williamoptics.com/telescopes/flt98_spec.php#
      >
      > I could be wrong, so you should probably contact WO directly on these
      > but on my SCT focuser the large silver thumbscrew on the bottom should
      > be there on yours as well. It is used to lock the travel in place,
      > but I honestly don't think I will ever need to use it because with the
      > tension adjusted I don't have any backlash or movement in mine. I
      > also don't do astrophotography either though, so with a camera, etc,
      > this might be needed to make sure there is no chance of slippage while
      > moving the scope around. The center allen screw is used for
      > adjusting the tension on mine. Maybe it's different on yours, or
      > maybe WO goofed and forgot something, or maybe something wiggled out
      > in shipping and you didn't spot it when you took it out.
      >
      > Who knows, but if someone else has the new M90 with the new focuser,
      > please speak up and help out.
      >
      > Timm
      >
      >
      > --- In William-Optics@yahoogroups.com, "gjcaunter" <gjcaunter@> wrote:
      > >
      > > Dear Anat,
      > >
      > > Hi, I'm Gareth and this is my first post on the WO Yahoo group. I was
      > > looking for information about the LinearPower focuser and this
      > > discussion caught my eye.
      > >
      > > I actually have a new WO Megrez 90 APO with the LinearPower focuser in
      > > my hands. Unfortunately there is a lot of backlash which I would like
      > > to try and correct. I had looked though all the documentation
      > > beforehand but found nothing relating to this design.
      > >
      > > Notable differences worth mentioning between the one pictured on the
      > > WO website and my own are: mine lacks the large silver ring (this is
      > > only relevant to SCTs I presume), and the central allen-screw and
      > > large thumb screw on the bottom are absent. There are threaded holes
      > > where both of these are located in the images on the website - the one
      > > that has the allen-screw is covered by a quality-control sticker on my
      > > Megrez. I'm 99% sure I haven't lost any screws (so to speak, you may
      > > disagree).
      > >
      > > Is it too early to ask if you or anyone else has experience with this
      > > focuser? I would appreciate any advice about how to adjust it.
      > >
      > > Best regards,
      > > Gareth
      > >
      > > --- 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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