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Fire effect lighting on walls


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#1 Jaxon Bridge

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Posted 07 July 2007 - 05:49 PM

I am planning a scene in a burning apartment. We don't actually see the fire (because I don't have the money), but I plan to simulate it by showing orange flickering light on the walls.

I am thinking about the best way to do this. My initial guess is to use orange gel over the lights, and have people wave things in front of the lights.

Also a smoke machine, I'm thinking.

I would think this might be difficult to pull off. Anyone tried this or have some more specific advice how to accomplish it?

-jaxon

Edited by Jaxon Bridge, 07 July 2007 - 05:51 PM.

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#2 Frank DiBugnara

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Posted 07 July 2007 - 06:26 PM

You can rent something called a flicker box. It is simply a box that passes current through it and causes the tungsten lamp to flicker. The good ones have several knobs on it that allow you to control the rate of the flicker and the intensities of both the high and the low end of the flicker. It can be believable if set up right.

In terms of the quality of light and which instrument to use: If you have the ability before the shoot, it might be fun to actually light a fire somewhere and study what the light does as it bounces off various parts of the room. I did this the other night as I was getting bored with the fireworks show. I kept looking the other way at how the light was hitting faces and wondering what the best way to recreate it would be.
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#3 Eon Mora

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Posted 07 July 2007 - 07:12 PM

I was working on a project with a very similar situation. the gaffer tried something I've never seen before: taking a flex fill, (you may need more than one depending) and bouncing whatever you use to source the fire in the silver or gold side, and shuffle and shake it around. Of all the fire techniques I've see this seems to be the best by far. flicker boxes are good but I've only had good experience with them when you've got multiple boxes on multiple lights at different rates and even then they're not the most natural.

i recently tried the flex fill trick on something and it worked great. its the kind of thing that is easy, cheap and looks natural.
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#4 Michael Nash

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Posted 07 July 2007 - 07:57 PM

This has been discussed here many times, so try doing a search.

Magic Gadgets makes a 3-channel flicker box called a Shadowmaker, that allows for 3 units at up to 2K per channel. I just used it again on the feature I just wrapped, and with 3 2K mighties plugged into it I got plenty of light and didn't have to gel the lights. It has different effects pre-programmed into it, and allows you to set the high and low levels on each channel, and the speed of the effect. By keeping the high level below 100%, you get a completely natural fluctuation in color temperature for flames.

Without a flicker box though, you'll still get a more convincing effect with two or more different lights. You can diffuse these lights slightly and have grips subtly wave their fingers in irregular patterns between the light and the diffusion. It takes some practice, and less is more. Don't be inclined to overdo it. The more extreme the effect, the more fake it tends to look.

Dimming aside, I've never felt the need to go any stronger than full CTO on tungsten to create a realistic fire color. Again, don't overdo it. Too strong or too red just looks fake and theatrical.
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#5 Jaxon Bridge

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Posted 07 July 2007 - 07:59 PM

I was working on a project with a very similar situation. the gaffer tried something I've never seen before: taking a flex fill, (you may need more than one depending) and bouncing whatever you use to source the fire in the silver or gold side, and shuffle and shake it around. Of all the fire techniques I've see this seems to be the best by far. flicker boxes are good but I've only had good experience with them when you've got multiple boxes on multiple lights at different rates and even then they're not the most natural.

i recently tried the flex fill trick on something and it worked great. its the kind of thing that is easy, cheap and looks natural.


great idea! i wonder what color gel i should get or if it would be necessary to mix colors on different lights. i'm thinking two sources each bounced into their own flex-fill. maybe two different shades of orange? i wish i could light a fire to analyze!
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#6 Jaxon Bridge

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Posted 07 July 2007 - 08:31 PM

This has been discussed here many times, so try doing a search.

Magic Gadgets makes a 3-channel flicker box called a Shadowmaker, that allows for 3 units at up to 2K per channel. I just used it again on the feature I just wrapped, and with 3 2K mighties plugged into it I got plenty of light and didn't have to gel the lights. It has different effects pre-programmed into it, and allows you to set the high and low levels on each channel, and the speed of the effect. By keeping the high level below 100%, you get a completely natural fluctuation in color temperature for flames.

Without a flicker box though, you'll still get a more convincing effect with two or more different lights. You can diffuse these lights slightly and have grips subtly wave their fingers in irregular patterns between the light and the diffusion. It takes some practice, and less is more. Don't be inclined to overdo it. The more extreme the effect, the more fake it tends to look.

Dimming aside, I've never felt the need to go any stronger than full CTO on tungsten to create a realistic fire color. Again, don't overdo it. Too strong or too red just looks fake and theatrical.


Shadowmaker looks great; and just a plain old dimmer too when you need one without the flicker, I see.

Question about dimming and color temperature: is the CTO still necessary with a flicker box? When light is dimmed, how does this effect color temperature?
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#7 David Regan

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Posted 07 July 2007 - 10:04 PM

When light is dimmed, how does this effect color temperature?


When you dim a light you get a warmer color temperature, hence I believe Michael's point about not really needing much in the way of gels. As to why this occurs you'd better ask someone else I don't really know the specifics

Good Luck
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#8 Jaxon Bridge

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Posted 07 July 2007 - 10:12 PM

When you dim a light you get a warmer color temperature, hence I believe Michael's point about not really needing much in the way of gels. As to why this occurs you'd better ask someone else I don't really know the specifics

Good Luck


In other words, the Kelvin temperature decreases? Warmer, in terms of temperature, usually means an increase (ie "the temperature outside is warmer today than yesterday"), but perhaps when discussing color temperature, it means a move to a warmer appearance, but actually a decrease in CT, right?
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#9 Jaxon Bridge

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Posted 07 July 2007 - 10:14 PM

Dimming aside, I've never felt the need to go any stronger than full CTO on tungsten to create a realistic fire color. Again, don't overdo it. Too strong or too red just looks fake and theatrical.


Michael - do you use the CTO when dimming, or only when you are not dimming (ie using a shadowmaker box, for example)?
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#10 Eon Mora

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Posted 07 July 2007 - 10:26 PM

great idea! i wonder what color gel i should get or if it would be necessary to mix colors on different lights. i'm thinking two sources each bounced into their own flex-fill. maybe two different shades of orange? i wish i could light a fire to analyze!


mix up the gels. put full CTO on one and maybe half straw on the other. play around and see what looks right.
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#11 Chris Keth

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Posted 08 July 2007 - 12:04 AM

mix up the gels. put full CTO on one and maybe half straw on the other. play around and see what looks right.


This is a great way to sell a fire effect. Fires are never one temperature throughout. There are hot places and cooler places. I like Full CTO on one, straw on one, and a nice golden yellow on another.

If you're shooting fast film or video, there's a rather nice cheap solution to this. Wire a fluorescent starter in the hot line to power the bulb. It will make a flicker that can be controlled depending on the wattage of the bulb. You can get nice random effects by doing this with a few bulbs of different wattages since they will flicker at different rates.

Edited by Chris Keth, 08 July 2007 - 12:07 AM.

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#12 David Regan

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Posted 08 July 2007 - 08:17 AM

In other words, the Kelvin temperature decreases? Warmer, in terms of temperature, usually means an increase (ie "the temperature outside is warmer today than yesterday"), but perhaps when discussing color temperature, it means a move to a warmer appearance, but actually a decrease in CT, right?


Yes you are correct, 'warm' colors indicate a lower temperature Kelvin, and 'cool' colors indicate a higher temperature Kelvin.
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#13 Shane Bartlett

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Posted 08 July 2007 - 09:27 AM

I was working on a project with a very similar situation. the gaffer tried something I've never seen before: taking a flex fill, (you may need more than one depending) and bouncing whatever you use to source the fire in the silver or gold side, and shuffle and shake it around.


You can also use sheets of regular household aluminum foil, if you don't have a flexfill, or if your flex is too large for the space you have to work with. I agree it looks much more natural than dimmers and flicker effects. I've done two interior fire scenes, and for both I used an ungelled tungsten fill light, one light pointed away from the subject, gelled with Roscolux #19 Fire (http://rosco.com/us/...olux.asp#colors), and a second light gelled with CTS, bounced into a sheet (or sheets) of foil and wiggled around at whatever speed suits your vision. Add a little fog. Looks great.

You'll have to fiddle with placement, or use a lower wattage lamp like a tweenie for the #19, else the red will be too heavy.
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#14 Jaxon Bridge

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Posted 08 July 2007 - 11:22 AM

I was working on a project with a very similar situation. the gaffer tried something I've never seen before: taking a flex fill, (you may need more than one depending) and bouncing whatever you use to source the fire in the silver or gold side, and shuffle and shake it around.
You can also use sheets of regular household aluminum foil, if you don't have a flexfill, or if your flex is too large for the space you have to work with. I agree it looks much more natural than dimmers and flicker effects. I've done two interior fire scenes, and for both I used an ungelled tungsten fill light, one light pointed away from the subject, gelled with Roscolux #19 Fire (http://rosco.com/us/...olux.asp#colors), and a second light gelled with CTS, bounced into a sheet (or sheets) of foil and wiggled around at whatever speed suits your vision. Add a little fog. Looks great.

You'll have to fiddle with placement, or use a lower wattage lamp like a tweenie for the #19, else the red will be too heavy.


These are all great ideas; i'm very happy with the responses, thank you!
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#15 Stuart Brereton

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Posted 08 July 2007 - 12:20 PM

Foil blankets, like those found in First aid kits are an excellent and cheap alternative to flexfills.
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#16 Michael Nash

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Posted 08 July 2007 - 06:21 PM

Michael - do you use the CTO when dimming, or only when you are not dimming (ie using a shadowmaker box, for example)?


I'll use full CTO when not dimming, or a slight grade of CTO when the highest output on the flicker gag looks too white. I just do it by eye.
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#17 Jaxon Bridge

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Posted 08 July 2007 - 06:26 PM

I'll use full CTO when not dimming, or a slight grade of CTO when the highest output on the flicker gag looks too white. I just do it by eye.


This might be a really silly questions but how do you eyeball color temperature?
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#18 Michael Nash

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Posted 08 July 2007 - 06:28 PM

This might be a really silly questions but how do you eyeball color temperature?


You just get to know it after awhile. You can eyeball strengths of CTO, just like you can eyeball 1/2 stop or 1 stop difference.
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#19 Jaxon Bridge

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Posted 08 July 2007 - 06:50 PM

You just get to know it after awhile. You can eyeball strengths of CTO, just like you can eyeball 1/2 stop or 1 stop difference.


This is a remarkable thing to hear. I didn't know the human eye could register color temperature. You're saying that as a light dims, you can also see the warming of its tone towards orange, even though you are using no gels? I'd think the vast majority of people only notice the obvious, that the light output was diminishing.

I guess if I had more lighting experience, I'd perhaps see this was a silly question. But I am truly astonished.

Are you one of those guys on that show, Heroes? :huh:

Edited by Jaxon Bridge, 08 July 2007 - 06:50 PM.

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#20 Michael Nash

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Posted 11 July 2007 - 05:31 PM

You're saying that as a light dims, you can also see the warming of its tone towards orange, even though you are using no gels?


Color temperature changes are easiest to see when there's a "white" reference color visible. If you have a raw tungsten light hitting a subject, and you turn on another one with 1/4 CTO on it, you should be able to see that it's different. Maybe you won't know immediately what density of gel it is, but you can see that it's different.

An entire set that's lit "warmer" than tungsten is easy to see by eye as well, especially when you first step onto the set. But the longer you spend in the presence of a single color, the more your eye/brain starts to "neutralize" that color and you start to see it as white.

"Seeing" color temperature is really no special talent, it's just something you develop practice with over time. With practice should be able to pick up a piece of CTO gel and identify it as 1/4, 1/2, or full just by looking at it. The way light looks through that gel takes a little more practice, though -- the brighter the light is (relative to ambient levels), the "whiter" the color tends to look.
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