DMX iris as projector douser?

Discussion in 'Multimedia, Projection, and Show Control' started by Joshualangman, May 20, 2019.

  1. Joshualangman

    Joshualangman Active Member

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    Hi all,

    Does anyone do this? Any reason not to? I'm concerned that the iris may be smaller than the lens even when full open. Does anyone make an iris-type product for a larger aperture than the typical S4 iris?

    Josh
     
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  2. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @Joshualangman Try Apollo and / or Rosco Labs for 'A' size irises; 'A' sizes have a larger aperture than 'B' or 'M' size irises. @GreyWyvern Have you any advice for our OP @Joshualangman ???
    Toodleoo!
    Ron Hebbard
     
  3. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Why bother? Why is an iris better than a flap or flag? The whole point of a projector douser is to "darken" video black. No one will, or should, notice how the sourced is further dimmed.
     
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  4. Joshualangman

    Joshualangman Active Member

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    The flag action has been noticeable in the past. Plan A was to do a custom gel string on a scroller, but this is plan B, and half as expensive, if it works.
     
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  5. Joshualangman

    Joshualangman Active Member

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    Although it occurs to me that irises don't close all the way … which would probably explain why no one else does this. So maybe this is a bad idea anyway.
     
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  6. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    In the olden days when Wybron made dousers as well as scrollers, they had the Eclipse. It was a venetian-blind type shutter. Some objected to parts of the mechanism staying in the path when open. The Eclipse II was a fully-closing iris type. You might try hunting one down. Came as large as 24" IIRC.

    [​IMG]
    Wybron Eclipse douser

    [​IMG]
    Wybron Eclipse II douser
     
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  7. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @Joshualangman In the cobwebs of my mind I believe I'm recalling an iris that had a little arm which swung up and blocked the tiny hole when irised down to its minimum diameter. Let's summon Control Booth's Super Trouper and Gladiator iris expert: @ship Can you help our O.P. @Joshualangman ?
    Toodleoo!
    Ron Hebbard
     
  8. ship

    ship Senior Team Emeritus Premium Member

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    c. 1950 Kliegl Dyna Beam
     
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  9. theatricalmatt

    theatricalmatt Well-Known Member

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    I've used City Theatrical projector dowsers, DMX Irises, and Wybron's Eclipse dowsers to dowse projectors.

    I like the City Theatrical dowser best, mainly because that's what it's supposed to do. (That being said, they overlooked its potential application for doing many other things besides....) That being said, the flag movement is often too noticeable by an audience, the motor is a little weak for very fast open and closes, and there's occasionally an issue with hysteresis; ie, it doesn't always make it to full open and full closed, especially if you're trying to eliminate the aforementioned noticeability aspect by only manipulating it from, say, 10 - 70% iinstead of 0 - 100%.

    The DMX Iris works surprisingly well, even with the small aperture remaining at center; maybe it's how we had the projector focused, maybe it's the distance we had it from the projector lens ... maybe any light bleed disappeared underneath the cyc light wash. The aperture size was never an issue, but I also used it in this specific application with a ~2500 lumen desktop projector with a fairly average lens, not a long-throw or extreme short throw lens.

    The Wybron Eclipse didn't work. Full stop. The vanes on the dowser were just too large, and no matter how close or far it was set from the projector, they cast shadows. We didn't try the 'iris' version of the Eclipse, as none were available to us.
     
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  10. Joshualangman

    Joshualangman Active Member

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    This is exceptionally helpful, theatricalmatt. Thanks.
     
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  11. ruinexplorer

    ruinexplorer Sherpa CB Mods Premium Member Fight Leukemia

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    I use the Eclipse 2 dousers, including partial close to feather video black in mostly dark projection. For the DMX iris, it depends on how close you have it to the lens and how large the image is at that point.
     
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  12. GreyWyvern

    GreyWyvern Apollo Staff

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    You would just need an iris that closes all the way, which some do. We have done scrollers (strings) for this purpose as well.
     
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  13. Joshualangman

    Joshualangman Active Member

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    Hi GreyWyvern, if we decide to do the gel string approach, I'll get in touch. Thanks.
     
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  14. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @Joshualangman Typing @ prior to GreyWyvern will cause the Control Booth 'Bat call' to flag Grey the next time he logs in. Mr. Wyvern is an Apollo staffer (and a good guy too.)
    Toodleoo!
    Ron Hebbard
     
  15. ship

    ship Senior Team Emeritus Premium Member

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    I found my photo's of the Iris Dowser plate on the Dyna Beam if anyone is interested in seeing how it worked. Let me know and I'll send/post the photos.
     
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  16. Scarrgo

    Scarrgo Well-Known Member

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    Interested....
     
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  17. ruinexplorer

    ruinexplorer Sherpa CB Mods Premium Member Fight Leukemia

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    If you could post photos, that would be wonderful.
     
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