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Re: Solved - Unable to focus DSI III with Brightstar filter wheel / IR block

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  • Wayne
    ... Good idea Don. Trouble is, I am now faced with how to get the front of the FR to mate with the back of the filter wheel. I have more adapters here than you
    Message 1 of 17 , Feb 23, 2013
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      --- In LX200GPS@yahoogroups.com, "Don D'Egidio" <djd521@...> wrote:
      >
      > Wayne,
      >
      > You should get less vignetting if you place the FR after the filter wheel.
      >
      > Don
      >
      Good idea Don.
      Trouble is, I am now faced with how to get the front of the FR to mate with the back of the filter wheel.
      I have more adapters here than you could shake a hairy stick at (I'm not sure of the relevance of the hairy stick in this case, but hey ho).
      So, my problem now is finding an adaptor with the male threaded diameter of the SCT adapter at one end(to acrew into the FR, and the male threaded diameter of the filter wheel at the other. What beast is this???

      Clear skies

      Wayne
    • John Mahony
      ... If the filters are 1.25 , you d get a bit of vignetting since the reducer lens is 1.5 diameter. BTW some vignetting is normal in nearly any
      Message 2 of 17 , Feb 23, 2013
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        ----- Original Message -----

        > From: Wayne <waynebyrne@...>

        > --- In LX200GPS@yahoogroups.com, "Don D'Egidio" <djd521@...>
        > wrote:
        >>
        >> Wayne,
        >>
        >> You should get less vignetting if you place the FR after the filter wheel.
        >>
        >> Don
        >>
        > Good idea Don.

        If the filters are 1.25", you'd get a bit of vignetting since the reducer lens is 1.5" diameter.

        BTW some vignetting is normal in nearly any astrophotograhy.  That's why imagers take flat field images to compensate. 

        > Trouble is, I am now faced with how to get the front of the FR to mate with the
        > back of the filter wheel.
        > I have more adapters here than you could shake a hairy stick at (I'm not 
        > sure of the relevance of the hairy stick in this case, but hey ho).
        > So, my problem now is finding an adaptor with the male threaded diameter of the
        > SCT adapter at one end(to acrew into the FR, and the male threaded diameter of
        > the filter wheel at the other. What beast is this???

        Scopestuff has virtually every adapter imaginable.  
        Start with an SCT-threaded T adapter between scope and filter wheel (any length should work, but keeping it short is usually better).  Then, assuming your filter wheel has male T-threads in back, use scopestuff part# TAFF
        http://scopestuff.com/ss_taff.htm

        to put the reducer behind the filter wheel.
        Then another SCT-threaded T adapter (of appropriate length) between the reducer and camera.  


        I believe the 3.3 comes with a short SCT-T adapter and (T-thread) extension tubes of various lengths, so I'd use that in back to get the separation distance you want.

        -John
      • John Mahony
        Always start with a good dew shield first before adding heat.  Heat requires a heavy duty power supply and heat rising in front of the OTA can cause your own
        Message 3 of 17 , Feb 23, 2013
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          Always start with a good dew shield first before adding heat.  Heat requires a heavy duty power supply and heat rising in front of the OTA can cause your own bad seeing.  The best dew shields are easily made yourself for a few $, and are flexible (easy to store).  Here's my standard reply on this issue:

          <http://tech.groups.yahoo.com/group/LX200GPS/files/dewshield.txt>

          -John


          ----- Original Message -----
          > From: Wayne <waynebyrne@...>
          >
          > My last venture out into the cold revealed I am now prone
          > to dew problems. I have recently moved locale and this was not a problem before.
          > I have purchased an IDDHM dew controller from Astrosmart and await it's
          > delivery. Also purchased a heater band and Telrad heater element. As I plan to
          > retire soon, I think it best to get these things now. "She who must be
          > obeyed" will not allow such extravagances? after I pack up working. Cheaper
          > to purchase from the States, even after adding our beloved Customs Duty (the
          > b@*^&*%s)...er...Blighters
          >
        • paul valleli
          Don, 13mm sounds just about right when I look at my experiments with the F/3.3 and my Canon 20D. That is why it works pretty well for video on my StellaCam3
          Message 4 of 17 , Feb 23, 2013
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            Don,
            13mm sounds just about right when I look at my experiments
            with the F/3.3 and my Canon 20D.
            That is why it works pretty well for video on my StellaCam3 from Adirondack
            Video. ( 1/2-inch Diagonal). I would expect similar performance
            with the MallinCam.
            Starman Paul


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