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WO reducer mark 3 and Megrez 90; problem with miss-shaped stars.

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  • Mikael
    Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8 reducer/flattener mark 3. I am having problems with miss-shaped stars in the edge of my photos, see an
    Message 1 of 7 , Mar 2, 2012
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      Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8 reducer/flattener mark 3. I am having problems with miss-shaped stars in the edge of my photos, see an example here.

      I got the suggestion that I should try changing the distance between the camera and the flattener. What is the appropriate distance between the sensor and the flattener for my system?
    • robert adamson
      Hi did anyone provide an answer to this query? robert From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com] On Behalf Of Mikael Sent: 02
      Message 2 of 7 , May 14, 2012
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        Hi did anyone provide an answer to this query?

         

        robert

         

        From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com] On Behalf Of Mikael
        Sent: 02 March 2012 15:42
        To: William-Optics@yahoogroups.com
        Subject: [William Optics] WO reducer mark 3 and Megrez 90; problem with miss-shaped stars.

         



        Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8 reducer/flattener mark 3. I am having problems with miss-shaped stars in the edge of my photos, see an example here.

        I got the suggestion that I should try changing the distance between the camera and the flattener. What is the appropriate distance between the sensor and the flattener for my system?


      • inZet
        The correct distance is 56mm. This is easy on Nikon cameras 46mm lens-to-chip distance, plus 10mm T-ring. On Canon, distance is 45mm so you have to add a 1mm
        Message 3 of 7 , May 15, 2012
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          The correct distance is 56mm. This is easy on Nikon cameras 46mm lens-to-chip distance, plus 10mm T-ring. On Canon, distance is 45mm so you have to add a 1mm ring. If the correct distance is not set, you get diamond stars at the edges of your image: but you get elonged stars in any case.
          With large sensors like those of modern DSLRs, field curvature at the edges is a serious issue.
          The WO Type III corrects 80% of the field; the Televue TRF-2005 for 90%; the Borg DG-L 0.85 #7887 you get a 100% corrected field.
          I own your same (amazing!) telescope and I bought the Borg. Never seen round stars at the edges on user images taken with our telescope model and the WO flatteners. With the Borg, they are perfect.

          Bye,
          Gianluca


          --- In William-Optics@yahoogroups.com, "robert adamson" <j.r.adamson@...> wrote:
          >
          > Hi did anyone provide an answer to this query?
          >
          >
          >
          > robert
          >
          >
          >
          > From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
          > On Behalf Of Mikael
          > Sent: 02 March 2012 15:42
          > To: William-Optics@yahoogroups.com
          > Subject: [William Optics] WO reducer mark 3 and Megrez 90; problem with
          > miss-shaped stars.
          >
          >
          >
          >
          >
          > Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8 reducer/flattener mark
          > 3. I am having problems with miss-shaped stars in the edge of my photos, see
          > an example here. <http://www.martenssonphoto.se/photo/m101_12.html>
          >
          > I got the suggestion that I should try changing the distance between the
          > camera and the flattener. What is the appropriate distance between the
          > sensor and the flattener for my system?
          >
        • robert adamson
          Gianluca Many thanks robert ... From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com] On Behalf Of inZet Sent: 15 May 2012 15:07 To:
          Message 4 of 7 , May 16, 2012
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            Gianluca
            Many thanks

            robert

            -----Original Message-----
            From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
            On Behalf Of inZet
            Sent: 15 May 2012 15:07
            To: William-Optics@yahoogroups.com
            Subject: [William Optics] Re: WO reducer mark 3 and Megrez 90; problem with
            miss-shaped stars.

            The correct distance is 56mm. This is easy on Nikon cameras 46mm
            lens-to-chip distance, plus 10mm T-ring. On Canon, distance is 45mm so you
            have to add a 1mm ring. If the correct distance is not set, you get diamond
            stars at the edges of your image: but you get elonged stars in any case.
            With large sensors like those of modern DSLRs, field curvature at the edges
            is a serious issue.
            The WO Type III corrects 80% of the field; the Televue TRF-2005 for 90%; the
            Borg DG-L 0.85 #7887 you get a 100% corrected field.
            I own your same (amazing!) telescope and I bought the Borg. Never seen round
            stars at the edges on user images taken with our telescope model and the WO
            flatteners. With the Borg, they are perfect.

            Bye,
            Gianluca


            --- In William-Optics@yahoogroups.com, "robert adamson" <j.r.adamson@...>
            wrote:
            >
            > Hi did anyone provide an answer to this query?
            >
            >
            >
            > robert
            >
            >
            >
            > From: William-Optics@yahoogroups.com
            > [mailto:William-Optics@yahoogroups.com]
            > On Behalf Of Mikael
            > Sent: 02 March 2012 15:42
            > To: William-Optics@yahoogroups.com
            > Subject: [William Optics] WO reducer mark 3 and Megrez 90; problem
            > with miss-shaped stars.
            >
            >
            >
            >
            >
            > Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8 reducer/flattener
            > mark 3. I am having problems with miss-shaped stars in the edge of my
            > photos, see an example here.
            > <http://www.martenssonphoto.se/photo/m101_12.html>
            >
            > I got the suggestion that I should try changing the distance between
            > the camera and the flattener. What is the appropriate distance between
            > the sensor and the flattener for my system?
            >




            ------------------------------------

            www.williamoptics.com www.williamopticsracing.comYahoo!
            Groups Links
          • robert adamson
            Hi Mikael Did you get a reply to this question, I have the same problem and am using a Sbig ST8300 Best regards robert From: William-Optics@yahoogroups.com
            Message 5 of 7 , May 28, 2012
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              Hi Mikael

              Did you get a reply to this question, I have the same problem and am using a Sbig ST8300

               

              Best regards

              robert

               

              From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com] On Behalf Of Mikael
              Sent: 02 March 2012 15:42
              To: William-Optics@yahoogroups.com
              Subject: [William Optics] WO reducer mark 3 and Megrez 90; problem with miss-shaped stars.

               



              Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8 reducer/flattener mark 3. I am having problems with miss-shaped stars in the edge of my photos, see an example here.

              I got the suggestion that I should try changing the distance between the camera and the flattener. What is the appropriate distance between the sensor and the flattener for my system?


            • Mikael
              Hi and thanks for the answer! Astrophotography has been off-season here in Sweden until now. I totally forgot about this post until a couple of days ago when I
              Message 6 of 7 , Aug 26, 2012
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                Hi and thanks for the answer! Astrophotography has been off-season here in Sweden until now. I totally forgot about this post until a couple of days ago when I had my astrophoto season premiere.

                Clear skies!
                Mikael


                --- In William-Optics@yahoogroups.com, "inZet" <gsordiglioni@...> wrote:
                >
                > The correct distance is 56mm. This is easy on Nikon cameras 46mm lens-to-chip distance, plus 10mm T-ring. On Canon, distance is 45mm so you have to add a 1mm ring. If the correct distance is not set, you get diamond stars at the edges of your image: but you get elonged stars in any case.
                > With large sensors like those of modern DSLRs, field curvature at the edges is a serious issue.
                > The WO Type III corrects 80% of the field; the Televue TRF-2005 for 90%; the Borg DG-L 0.85 #7887 you get a 100% corrected field.
                > I own your same (amazing!) telescope and I bought the Borg. Never seen round stars at the edges on user images taken with our telescope model and the WO flatteners. With the Borg, they are perfect.
                >
                > Bye,
                > Gianluca
                >
                >
                > --- In William-Optics@yahoogroups.com, "robert adamson" <j.r.adamson@> wrote:
                > >
                > > Hi did anyone provide an answer to this query?
                > >
                > >
                > >
                > > robert
                > >
                > >
                > >
                > > From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
                > > On Behalf Of Mikael
                > > Sent: 02 March 2012 15:42
                > > To: William-Optics@yahoogroups.com
                > > Subject: [William Optics] WO reducer mark 3 and Megrez 90; problem with
                > > miss-shaped stars.
                > >
                > >
                > >
                > >
                > >
                > > Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8 reducer/flattener mark
                > > 3. I am having problems with miss-shaped stars in the edge of my photos, see
                > > an example here. <http://www.martenssonphoto.se/photo/m101_12.html>
                > >
                > > I got the suggestion that I should try changing the distance between the
                > > camera and the flattener. What is the appropriate distance between the
                > > sensor and the flattener for my system?
                > >
                >
              • john robert adamson
                Hi I have the same issue with my Megrez 90, still persisting with the WO M3 until funds allow the upgrade. I am not so troubled as I am using a ST8300 which is
                Message 7 of 7 , Aug 27, 2012
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                  Hi
                  I have the same issue with my Megrez 90, still persisting with the WO M3
                  until funds allow the upgrade. I am not so troubled as I am using a ST8300
                  which is not a full sized chip

                  robert

                  -----Original Message-----
                  From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
                  On Behalf Of Mikael
                  Sent: 26 August 2012 14:08
                  To: William-Optics@yahoogroups.com
                  Subject: [William Optics] Re: WO reducer mark 3 and Megrez 90; problem with
                  miss-shaped stars.

                  Hi and thanks for the answer! Astrophotography has been off-season here in
                  Sweden until now. I totally forgot about this post until a couple of days
                  ago when I had my astrophoto season premiere.

                  Clear skies!
                  Mikael


                  --- In William-Optics@yahoogroups.com, "inZet" <gsordiglioni@...> wrote:
                  >
                  > The correct distance is 56mm. This is easy on Nikon cameras 46mm
                  lens-to-chip distance, plus 10mm T-ring. On Canon, distance is 45mm so you
                  have to add a 1mm ring. If the correct distance is not set, you get diamond
                  stars at the edges of your image: but you get elonged stars in any case.
                  > With large sensors like those of modern DSLRs, field curvature at the
                  edges is a serious issue.
                  > The WO Type III corrects 80% of the field; the Televue TRF-2005 for 90%;
                  the Borg DG-L 0.85 #7887 you get a 100% corrected field.
                  > I own your same (amazing!) telescope and I bought the Borg. Never seen
                  round stars at the edges on user images taken with our telescope model and
                  the WO flatteners. With the Borg, they are perfect.
                  >
                  > Bye,
                  > Gianluca
                  >
                  >
                  > --- In William-Optics@yahoogroups.com, "robert adamson" <j.r.adamson@>
                  wrote:
                  > >
                  > > Hi did anyone provide an answer to this query?
                  > >
                  > >
                  > >
                  > > robert
                  > >
                  > >
                  > >
                  > > From: William-Optics@yahoogroups.com
                  > > [mailto:William-Optics@yahoogroups.com]
                  > > On Behalf Of Mikael
                  > > Sent: 02 March 2012 15:42
                  > > To: William-Optics@yahoogroups.com
                  > > Subject: [William Optics] WO reducer mark 3 and Megrez 90; problem
                  > > with miss-shaped stars.
                  > >
                  > >
                  > >
                  > >
                  > >
                  > > Hello. I have a Megrez 90 (621mm f/6.9) and a WO 0.8
                  > > reducer/flattener mark 3. I am having problems with miss-shaped
                  > > stars in the edge of my photos, see an example here.
                  > > <http://www.martenssonphoto.se/photo/m101_12.html>
                  > >
                  > > I got the suggestion that I should try changing the distance between
                  > > the camera and the flattener. What is the appropriate distance
                  > > between the sensor and the flattener for my system?
                  > >
                  >




                  ------------------------------------

                  www.williamoptics.com www.williamopticsracing.comYahoo!
                  Groups Links
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