How to emulate mercury vapor with (RGB) LED lights?

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  • This topic has 4 replies, 3 voices, and was last updated 1 month ago by Stip.
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  • #215921
    Stip
    Participant

      How do you best emulate mercury vapor light with LED lights, either RGB or daylight/tungsten?

      Over a decade back, David Mullen posted on another forum:

      Mainly I’ve used 1/4 CTO + 1/2 Plus Green on HMI’s (similar to a Cool White fluorescent color).

      Sometimes I’ve used tungstens in other scenes with Cyan 60 gel, though if matching to HMI’s with the combo I mentioned above, I use 3/4 CTB + 1/2 Plus Green on the tungsten.

      Though I find that real mercury vapors would be more like Full Plus Green rather than 1/2 Plus Green in terms of the greeness.

      I wonder what’s best practice with todays RGB and/or bi-color LED lights?

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    • #215924
      Roger Deakins
      Keymaster

        I would use some gel, just as David suggested. You could always get a swatch of small leaves of gel than match an LED to the color you prefer. Its either that or match a full color LED to a mercury vapor fixture.

        #215926
        Stip
        Participant

          Thank you!

          I’ll follow David’s routine then.

          A follow up question: did mercury vapor street lamps in the 70’s / 80’s have more tint than later variations?

          #215932
          dmullenasc
          Participant

            I think mercury vapor lamps vary somewhat in color just as Cool White fluorescents do, some have a lot more green in them. But you have to factor in how film stocks of the past reacted to that narrow wavelength in the cyan range versus how a digital sensor would react today.

            It gets to the point where you might as well just pick a degree of cyan you like — at the saturation level you like — when using an RGB LED rather than worry about the accuracy of recreating a lamp of the past (unless you are trying to match the LED to a real mercury vapor lamp in the shot.)

            Here’s a shot from a movie I did 15 years ago which had a real mercury vapor lamp on the corner of the trailer, and one on a streetlamp, shot on Fuji 500T pushed one-stop. But the pool of light over the phone booth was a tungsten parcan gelled with cyan:

            #215934
            Stip
            Participant

              Thank you!

              That’s a very good point – the goal would indeed be to emulate mercury vapor street lamps as they looked on film stocks (of the past). I have a good idea now where to start and what to look for.

              Thank you both for sharing your knowledge.

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