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Thread: Beam show basics?

  1. #1
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    Default Beam show basics?

    For those of you who are experienced doing "beam shows" at home or in small venues, can you give me an idea of how you set things up to give the best show without undue risk of blinding anyone?

    I'm looking for ideas on distances between the projector and audience, viewing angles, use of screens, use of fogger / hazer, etc.

    I'll probably be working with 100mW blue, 200(+) mW red, and 300 mW green lasers, RGB configuration, 30K scanners, controlled by a Pangolin FB3. I want to provide the best view possible, with the least chance of getting anyone hurt!

    On a similar note - how do you guys position and setup your digital cameras for some of those awesome beam shot photos I've seen posted?!

    Thanks!

    RR
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
    Sweet.....

  2. #2
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    northern maine.
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    Default

    stuka-

    to clarify,i would ask if by beam show you mean straight beam shots without scans?
    of course with the right software you can do both in the same show.

    i have tons of experience using bounce mirrors and the difference they make is huge.
    you can encompass the whole room and you get different point sources thus alleviating the tedium you can get from a single point source.
    doing beam/mirror chases while scanning is the "mutt's nutts"as someone said in another thread.

    of course,keep your mirrors high up over the crowds heads and do your adjusting before the show starts and no one is in you setup area.

    a key for me is doing a double bounce from the back of the room and returning to mirrors in front adjacent to the laser.
    back of room mirrors can work by themselves but often the effect is lost because no one is looking to the back of the room.
    also,with scanners,you can't place the initial target mirrors too far apart or you will be outside the range of your scan angle.

    just use the second bounce mirrors to get width.
    that's another advantage a relatively primitive beambox has in this regard,you can target as wide as you want.
    sometimes i turn modules 180degrees and hit mirrors high and behind the stage.
    that's nice because i get the front of room beam with no need for a double bounce.
    symetrical(sp) patterns are good but the geometry of the venue often dictates otherwise
    for these you can make sure your beams cross at the same point at the same height by walking out,looking and walking back and adjusting.
    repeat till you need a beer
    oh yeah i forgot...
    up the ladder,down the ladder... also repeat till wiped
    use fs mirrors of course and get creative.

    peace,
    wes

    edit,i won't go on too long, but i would suggest a hazer.
    this will give a steady base of particles.
    i just run mine all night as the fluid consumption is very low.
    you can always add fog but fog alone is not my preference.
    peace
    Last edited by wes; 07-19-2007 at 07:17.

  3. #3
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    Default

    Thanks for the info - great ideas for room-crossing beamshots!

    Starting out, I will probably be limited to basically my home or very small venues, and just the projector. I'll want to utilize the capabilities of the hardware to create multicolor scanned beam effects. With this in mind, what kind of distance do you need between the viewers and the projector to get a safe viewing angle for the audience?

    Also, what is the real advantage to using a "scrim" screen that I have heard some of the other folks refer to on this forum?

    Thanks!

    Randy
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
    Sweet.....

  4. #4
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    Smile RE: Scrims

    Hi Randy;

    A scrim allows the scanned image to "float" in the air. Because a scrim is so thin and porous (think window screen), the audience often can't see it if the room is already dark. So when you start scanning an image, you get a bright reflection off the nearly-invisible scrim hanging in the air. The result is that you see your image just hanging there in the middle of the room. (Magic!) Also, some portion of the beam will make it through the scrim, so you will end up with a second, dimmer image on the wall behind the scrim.

    I've seen this used to great effect on stage. They set the projector at the front of the stage and aimed it back towards the backstage area. They had a scrim about 15 feet in front of the projector, then another one about 25 feet away, and finally a white screen about 40 feet away at the very back of the stage. Sitting in the audience, you ended up seeing 3 distinct copies of the same scanned image. Obviously the first two were smaller than the main one on the screen in the back, but the effect was pretty cool nonetheless.

    I've also seen small scrims used for the very center of the scan angle on a projector that was aimed out towards the audience. Outside of the scrim area the show was beams and fans, but inside of the scrim area they displayed graphics and text. (Of course, the text had to be reversed, because the audience was behind the scrim.)

    When you get back home and have some time, pick up some window screening at a hardware store and experiment with it; you'll be able to re-create these effects pretty easily.

    As far as a safe distance for viewing beams, that's up to you. If you're doing a professional show, there are the CDRH guidelines that need to be followed, but in your home you probably won't be able to comply with those gidelines. (Unless you've got *really* high ceilings, that is!) I normally do shows in my living room, which is about 28 ft long by 14 ft wide. I set the projector on the lid of the vertical case for the stereo, which is about 20 ft from the wall that I display on. Then I roll it out a few feet into the room.

    For graphics shows I crank in about 40% positive offset on the Y galvo to put the scanned image on the sloped ceiling. But for beamshows I lower the Y offset to bring the very bottom edge of the beams down to just above head level near the back wall. Then people can watch the show standing up from back there, or from a seated position on the couch in front of that area. Once in a great while I'll lower the Y offset down below the horizontal plane so I can scan a circle and put someone inside it. This is risky, because a scanner failure at that point could potentially end up sending a static beam into someone's eye. I normally dial the power back a bit when I do this too. (You can talk about the risks all you want, but everyone should experience being inside a scanned cone of light at least once!) That's where my avitar picture came from, BTW...

    Adam
    Last edited by buffo; 07-23-2007 at 05:46.

  5. #5
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    Default

    Great info - thanks as always!

    Randy
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
    Sweet.....

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