Conventional Fixtures Altman 6" Fresnel w/ No Lens

Discussion in 'Lighting and Electrics' started by shiben, Oct 31, 2013.

  1. shiben

    shiben Well-Known Member

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    Hey all. I am trying to get some ballen shadow effects on a series of drops, and plan on using a altman fresnels with their fresnel lens removed to cover the drops with light. Anyone have an idea of the beam/field angle of a fresnel with no lens? Intuition says its wider but short of setting up a demo and doing math, I was wondering if anyone had ideas...
     
  2. BillESC

    BillESC Well-Known Member

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    At the flood setting it will be very wide, around 120 degrees.
     
  3. JD

    JD Well-Known Member

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    Might want to put a screen in a gel frame on it. Without the lens, lamp failure might be a bit nasty.
     
  4. shiben

    shiben Well-Known Member

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    Good idea. Will the screen get projected at all?
     
  5. shiben

    shiben Well-Known Member

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    Excellent. Thanks!
     
  6. JD

    JD Well-Known Member

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    I am thinking not as the filament area is not a tight point source and the screen would only be 3 inches in front. If there was more distance between the lamp and the screen it might show up. Only one way to know for sure.
     
  7. Wood4321

    Wood4321 Active Member

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    I would remove the reflector as well, and I would replace the lens with a piece of tempered glass, just in case the lamp fails. Then you also don't have to worry about the screen being projected.

    Edit for clarification:
    Removing the reflector makes the the shadow projection a bit sharper, since the light is coming from a single source, and not from multiple. (The reflector acts as a large source, not a point)
     
  8. techieman33

    techieman33 Well-Known Member

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    You shouldn't see the screen projected, just like you don't see it in cyc lights with screens. I would go with Woodj32177's suggestion of glass though since the screen can cut down on overall light output.
     
  9. BillESC

    BillESC Well-Known Member

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    No need to remove the reflector. The time I did this, I was lighting set piece 45 RPM records ranging in size up to 28' in diameter. The three records were flown on the second and third electrics and the first electric was the only option to light them from. It worked extremely well. Very flat coverage.
     
  10. Les

    Les Well-Known Member

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    Also, you can't remove an Altman 6" fresnel's reflector without popping some rivets or breaking spot welds. I wouldn't attempt if it's not your light.
     
  11. techieman33

    techieman33 Well-Known Member

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    You could always put a piece of black wrap over the reflector and see what happens.
     
    Wood4321 likes this.
  12. shiben

    shiben Well-Known Member

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    Yeah I was looking at it and its probably more work than its worth even if it was screws or something. Its already a much nicer shadow than even a source 4 90 is bringing out, and with a much smaller unit. Im pretty happy with what Im getting.

    As for the glass/screen thing, I wish I could afford glass but I have to do 30 of these things and somehow also get 2 lamps, so screen it is.
     

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