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Mirror Making event

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  • Jones Lyle A. (DNREC)
    Since I have heard from no one except Terry Young about the mirror making event, I should assume that the mirror making event is off for this year and I
    Message 1 of 6 , Nov 30, 2004
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      Since I have heard from no one except Terry Young about the mirror making event, I  should assume that the mirror making event is off for this year and I should cancel I reservation at the St. Jones Reserve.  Lyle  

    • Jerry Truitt
      I would be interested in doing it. I contacted Newport Glass they said they would e-mail me a quote but I have not received it yet. I also talked to Dr.
      Message 2 of 6 , Nov 30, 2004
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            I would be interested in doing it. I contacted Newport Glass they said they would e-mail me a quote but I have not received it yet. I also talked to Dr. Hanagan who said he would be willing to participate.
            However I agree if we don't have enough enthusiasm to even respond we should cancel the event and not leave people hanging.
      • David M Groski
        The 4.25 Schiefspegler or Schief for short or sometimes called Sheepspringler is all spherical tilted optics telescope. It is unique in that the both the
        Message 3 of 6 , Dec 2, 2004
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          The 4.25" Schiefspegler or Schief for short or sometimes called
          'Sheepspringler' is all spherical tilted optics telescope. It is unique in
          that the both the primary mirror and secondary mirror have the same but
          opposite sign radius of curvature. What this means is that the convex tool
          used to grind the concave primary becomes the secondary. Once the primary
          is figured to a sphere it is used the test the figure on the secondary by
          interference. The light path is unobstructed and the F-ratio is 27. The
          'scope is designed for high resolution lunar,planetary and double star
          work. It performs as well or better then a refractor and has no color. I
          took the original Anton Kutter design that was published back in the 1961
          and used a program that tweaked it. The original design had about 1/4 of
          residue coma. In my design this had been reduced to below 1/10 wave. Bill
          Cheng has built one and it was displayed at last years Mirror Making class.
          It gave some truly excellent images. He had it this years Stellafane.
          Unfortunately the skies weren't clear long enough for a form optical
          judging, but a number of people including the former head of the optically
          judging committee did look through it and stated that it star tested
          perfectly. It was one of the possible projects for a future mirror making
          event.

          - Dave



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        • Tom Dove
          I might be interested; last year s seminar was a lot of fun and I m thoroughly enjoying my 6 f/8 Dob that I ground the mirror for there. I must have missed
          Message 4 of 6 , Dec 2, 2004
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            I might be interested; last year's seminar was a lot of fun and I'm thoroughly enjoying my
            6" f/8 Dob that I ground the mirror for there. I must have missed the announcement in the
            newsletter for the next event.

            What projects are proposed? By springtime, cabin fever should have me ready for another
            project as long as it doesn't duplicate something I already have.

            -- Tom Dove
          • James T. Morgan
            Thanks for the explanation, this sounds cool but at F27 how long is the scope? Can you remove the central obstruction in a regular Newtonian by tilting the
            Message 5 of 6 , Dec 3, 2004
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              Thanks for the explanation, this sounds cool but at
              F27 how long is the scope?

              Can you remove the central obstruction in a regular
              Newtonian by tilting the optics? This intrigues me
              and I suspect that it introduces a host of other
              problems so it is not so easy to do. Just wondering
              how wonderful it would be to gain that area back for
              viewing.

              James




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            • David M Groski
              James, The optical path is folded and the secondary amplifies. The scope is about 3 long. There are pictures of Bill s scope on the Stellafane s website
              Message 6 of 6 , Dec 3, 2004
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                James,
                The optical path is folded and the secondary amplifies. The 'scope is
                about 3' long. There are pictures of Bill's 'scope on the Stellafane's
                website under 'All scope entered .... " for 2004. Both the primary and
                secondary are tilted so they cancel out the aberrations introduced by
                tilting. Planetary detail is very sharp. I know a number of people looked
                through Bill's scope at last year's mirror making class and were very
                impressed with the quality.
                Herschel was the first to tilt the primary on a Newtonian to get read of
                the secondary. This only works well for a f/35 or longer system up to about
                a 6" mirror, but it also leads to a really long tube !



                "James T. Morgan"
                <morganjt56@yahoo
                .com> To
                delmarvastargazers@yahoogroups.com
                12/03/2004 10:20 cc
                AM
                Subject
                [delmarvastargazers] Mirror Making
                Please respond to event scheifspegler
                delmarvastargazer
                s@yahoogroups.com









                Thanks for the explanation, this sounds cool but at
                F27 how long is the scope?

                Can you remove the central obstruction in a regular
                Newtonian by tilting the optics? This intrigues me
                and I suspect that it introduces a host of other
                problems so it is not so easy to do. Just wondering
                how wonderful it would be to gain that area back for
                viewing.

                James




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                by return e-mail and delete this e-mail from your system. Unless
                explicitly and conspicuously designated as "E-Contract Intended",
                this e-mail does not constitute a contract offer, a contract amendment,
                or an acceptance of a contract offer. This e-mail does not constitute
                a consent to the use of sender's contact information for direct marketing
                purposes or for transfers of data to third parties.

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