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Large LED bulbs for film lighting?

Hey folks -

I'm just getting into amatuer filmmaking. I took a class on low budget lighting and we spent a great deal of time talking about scouting locations properly for lighting. Two things you really have to worry about are power draw and heat. With movie lighting, it's easy to blow the circuits because several 1000 watt bulbs draw a lot of power, and then also they create a lot of heat. This makes it easy for them to melt plastic filters, their housing, even blow up the bulbs themselves. That's why you hear the director call "Lights! Camera! Action!" -- because the lights are shutdown between takes to cool off.

Of course, most of these problems are caused by the fact that these are incandescent bulbs, which waste a lot of energy as heat. A lot of these problems could be sovled by more effecient lighting techniques -- say LED bulbs.

I know that LED bulbs are just now getting into home lighting, but I wonder why they aren't used in more film lighting. Film lights are expensive anyway, so I would guess LED lights could compete more effectively than in the home.

Why are LEDs so small?

Is it possible to get an LED bulb that kicks out 1000 watts of light, yet leave a small current and heat footprint?

Reply to
lawpoop
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do multicoloured LED spotlights.

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Reply to
Andy Baxter

P.S. they aren't on their site, but this was reported in the Sep 2003 issue of electronics world, so maybe they still do them, or know someone who does.

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Reply to
Andy Baxter

I don't think you can get as good a white color with LEDs as with incandescents. White LEDs tend to be on the blueish side.

Also, LEDs are less efficient than incandescents if operated at full power. To beat the efficiency of incandescents, I believe you need to reduce the power level quite a bit and add more LEDs to make up for the lost light.

-Bill

Reply to
Bill Bowden

(snip) Most white LEDs are really blue LEDs thinly coated with a phosphor that absorbs blue light and emits yellow. The combination of blue (that gets past the phosphor) and yellow fool the eye into seeing roughly white. But there are big chunks of the visible spectrum missing, specifically green and red. So green or red objects (things that absorb blue and yellow, but reflect green or red light) look off color and dim when illuminated by white LEDs.

Reply to
John Popelish

As it turns out, a 1,000 watt incandescent puts out about 90-100 watts of light, maybe 500-600 watts of infrared and 300-400 or so watts of non-radiant heat (roughly).

1,000 watts dumped into the most efficient LEDs out there, with those LEDs being run at full power, may get you 150 watts of visible light, not much infrared, and almost 850 watts on non-radiant heat (roughly). The ratio of heat to light actually increases due to lack of getting rid of heat as infrared. Just to make things worse, LEDs are less tolerant of high temperatures than incandescents. So, heat issues in fixtures are a reason to use incandescent lamps (including halogen lamps) over LED.

But the main reason is that high power LEDs and high power LED cluster lamps are expensive. A 5-watt LED in small quantities costs around $30, give-or-take.

There are LED stage and filming lights, but they are not yet in really widespread use. Advantages of LED stage and filming lights in general are, at least theoretically:

  1. Ability to achieve some shades of colored light more efficiently than with incandescents and filters
  2. Ability to change color electrically
  3. Strobing capabilities that incandescents don't have

But for high efficieny of producing light for filming, what they tend to use is special metal halide lamps such as HMI and the like.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

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