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To tilt or not to tilt a dome

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  • Matthew Linke
    Hi all, We are leaning (tilting?) toward a tilted dome, but are trying to decide on the degree of tilt. None of us is really interested in a very steep tilt.
    Message 1 of 4 , Aug 8, 2013
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      Hi all,

      We are leaning (tilting?) toward a tilted dome, but are trying to decide on
      the degree of tilt. None of us is really interested in a very steep tilt.
      It's only a 30 footer. I have have heard of everything from a few degrees
      to twenty-something. I am intrigued by the approximately ten degree tilts
      I have heard of. Many of you have tilted domes. I would love to hear pros
      and cons. As in all things with the process, money will come into play at
      some point.

      Regards,

      Matt Linke

      --
      Matthew Linke
      Planetarium Director
      State Chair, Great Lakes Planetarium Association (GLPA)

      University of Michigan Museum of Natural History Planetarium
      Room 4508 Museums
      1109 Geddes Ave.
      Ann Arbor, MI 48109
      734-647-1381 (voice)
      734-647-2767 (fax)
      www.ummnh.org
    • Drew
      Matthew: First dome I ever worked in was in Roanoke VA at the Hopkins Plantarium. It is a 40-foot dome tilted 41-degrees. Now you have heard of much more
      Message 2 of 4 , Aug 9, 2013
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        Matthew:

        First dome I ever worked in was in Roanoke VA at the Hopkins Plantarium. It is a 40-foot dome tilted 41-degrees. Now you have heard of much more than 20-degrees!
        The purpose was three fold, there are 140 seats that need a clear view of the sky (Spitz 512) the five-pan, triple stacked slide system, and the 35/70mm film projector. The design is quite unique and was fun to work and learn in. It got me where I am today.
        There are a few other unique items that I won't go into here.

        I have worked in flat, tilted and extreme tilted. My favorite is what I have now, slightly stair stepped seating for 160 and a 12.5-degree tilted dome. I believe it to be the right thing for a dome that is used as a theater, planetarium, lecture and classroom facility and more.

        My choice: uni-directional seating and 10 to 15 degree tilt. I like both Spitz and Astro-Tech domes equaly.

        This is my two cents, let me know if it helps.

        Regards,
        Drew
        Rauch Planetarium
        Univ. of Louisville
      • Hari Nandakumar
        Hi Matt, I am probably biased, since ours is a tilted dome, but I see a lot of pro points for tilted domes. :) We have a 15 degree tilted dome and
        Message 3 of 4 , Aug 9, 2013
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          Hi Matt,

          I am probably biased, since ours is a tilted dome, but I see a lot of pro
          points for tilted domes. :)

          We have a 15 degree tilted dome and uni-directional seating. Nowadays, most
          of the fulldome shows available are more suited for unidirectional seating.
          Some of the other planetaria in India, which started out with concentric
          seating and optomechanical projection systems, ripped out their seats and
          converted to uni-directional seating when they upgraded to fulldome
          projection. Others are trying to roll their own shows to suit their
          concentric seating. So, in our case, the uni-directional seating and the
          tilted dome seems to be a good choice.

          There's a pic of our theatre at
          http://home.saispace.in/home/photo-gallery

          With a tilted dome and uni seating, the horizon can go lower down than with
          concentric seating without tilt, since stepped seats mean that the people
          in the back rows are not blocked by the people in front. The seats can be
          more upright, tilting at an angle rather than completely reclining, too.
          This could help with increasing seat density, too.

          There were some older threads some time back about concentric vs
          unidirectional seating, tilted domes, etc those may also be relevant for
          you:

          http://groups.yahoo.com/group/fulldome/message/1014

          http://groups.yahoo.com/group/fulldome/message/1139


          Yours,

          Hari Nandakumar
          Sri Sathya Sai Space Theatre
          Prasanthi Nilayam
          AP - 515134
          India
        • Donald Knapp
          Matt, Here s one caveat to consider with a tilted dome. Because of the tilt, you will not have a continuous horizon completely around the dome. This isn t a
          Message 4 of 4 , Aug 12, 2013
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            Matt,

            Here's one caveat to consider with a tilted dome. Because of the tilt, you
            will not have a continuous horizon completely around the dome. This isn't a
            problem if you're only presenting fulldome video, but it can be
            problematical when giving star presentations. For example, when I give a
            lesson on the seasons, I like the students to track the sun's apparent
            motion from horizon to horizon. With a tilted dome, if the students are
            facing south, this cannot be done properly when the sun is north of the
            celestial equator, because the the horizon stops at the east and west
            points.

            Just something to consider.

            Don Knapp
            Retired & Domeless
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