| how do I light/shoot fire?
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 | how do I light/shoot fire?
by funkengine on Nov 12, 2001 at 8:58:54 pm |
Hey everyone. I'm planning a shoot within the next month in which I will have to record some fire/explosion type stuff. For your consideration: The fire will be from flash paper, which is about two stops brighter than a good, strong bic lighter. I'm shooting with a Canon XL1. My questions are:
1. How do I light the scene so that the flame doesn't get illegally bright while still having the surrounding scene visible and well-lit? I'm concerned that stopping down will mess up my surrounding scene. So then, do I light the scene to kingdom come and stop down? If I do that, will I lose the pop/pizzazz of the flame, since it will not contrast with the background as much?
2. Flash paper burns quickly, very quickly, and the shape of the flame is beautiful and changes around very fast. Would using a faster shutter speed help to capture some more distinct flame modelling?
I appreciate all your input.
Chris Yeiser
p.s. I'm going to post this on the Canon DV and Broadcast Video boards as well. I hope you don't mind.
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• | | | |  | Re: how do I light/shoot fire?
by JOHN SHARAF on Nov 12, 2001 at 9:58:32 pm |
The challange is to illuminate the rest of the scene as if the fire is the source light. A good trick is to use a gold mylar sheet, hang it on a c-stand and aim a quart light into it. By aiming the reflection and adding some subtle movement you can pretty much make it look like the fire is the source.
You need not aim it at the fire itself as that obviously creates its own illumination, but any background or person nearby will benefit from this treatment. Choose a size light or distance that brings the intensity almost to the brightness of the fire itself, remember it's only natural that the light falls off as the distance from the source increases. If the light cast by the fire is brighter than the fire itself even an unsophisticated viewer will sence something's wrong!
You can use your monitor to adjust the color to your likeing by further gelling the quartz light with more amber or red to pickup the tint of the actual fire.
There are commercial "flicker" generators available but this method is more organic and feels better to me. Another "organic" method is to make a "flicker stick" with strips of fire-like colored gels attached and jiggle it slowly in front of the movie light as it aims at the intended subject.
All these (and other) methods merely intend to recreate what you would otherwise observe when the action your filming transpires in the real world. Take a minute and observe the effect in reality and then do your best to summons some "tricks" to recreate what you saw on tape (or film). Because this is not an everyday observation for us modern people you must consciously study what it is you're trying to recreate!
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• | | | |  | More tricks for shooting fire...
by Leo Ticheli on Nov 12, 2001 at 10:39:56 pm |
I've used all the methods John described, except for the commercial flicker generators, and they all work well, especially the flicker-stick with hanging strips of various colors of warming gel. The trick is to get the giggle just right and to balance between a hard source which looks too artificial and a soft source which diffuses the light through the gels too much. I've also made a light source consisting of several household bulb bases all wired through individual mercury switches. You simply wobble the board and the lights go on and off in a random fashion, and the number of lights on or off is variable as well. Of course you gel each globe with a different color. This works very well, especially for close-ups.
I must say that these days I try to use the practical sources whenever I can; modern film stocks and very sensitive digital cameras make it possible to shoot at very low light levels and there's just nothing like the real thing... at least much of the time.
Now as to your question about balancing exposure for the flame itself and the surrounding scene, I'm afraid I don't have a satisfactory answer. Even the human eye with it's magnificent dynamic range can't properly expose the center of a flame without losing the surrounding area in black, unless the surrounding area is almost as hot as the flame... but then, what's the point? Film has quite a good range, but even with Kodak's best efforts, it is unlikely you will have enough detail in your overall scene if you expose for the flame itself. My HD camera does a pretty good job with this; I have a shot on my demo of a girl lit only by a single match and candle, but even then it's not possible to see all the detail in the flame without losing the detail in the shadow area, even by manipulating the knee.
There is a way to achieve this in post; with film you make two passes through the Rank, one exposed for the flame, the second exposed for the surrounding scene. If the scene is a lock-down, you just draw a mask around the fire and combine the two exposures into a single composite. You do the same thing shooting on tape, but you shoot exposed for the flame and then lift the level of the rest of the scene with the color corrector.
If the camera or the flame is moving in the shot, you may also have to do some motion-tracking or rotoscoping, but it's really not that big a deal if you talk to your Compositor first.
A friend of mine once suggested that the best solution for such situations is to, "learn to love it." Perhaps you will find that the burned out whites in your flame are indeed a thing of beauty!
Good shooting!
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• | | | | | Re: More tricks for shooting fire...
by Wes Malkin on Nov 15, 2001 at 4:13:19 pm |
Lots of great info here from Leo & John. I think the point of observing the flame naturally is important... see what it does to your eye. What does it do to objects around it... how much light is being bounced around?? Is is really a "flicker" or just a bright flash. If it's just a flash you might want to "cheat" a bit and apply a flicker so it's a little sexier.. depending on the shot of course. I always they to use the real fire for effect when possible if the actual flame is seen in the shot. It will be important to get the timing of the flash paper right for this to be effective. You don't want to have the "gag" going while the flame is not burning. With that being said balance of the light will be a very improtant issue here. Your levels will need to be low enough so the flicker will be noticable but not overexpose the flame. It was suggested that you do the gag twice at different exposures and composite the images... that sounds like a very good suggestion to me. If it were to be shot on film I'd either do as Leo suggested and do 2 passes or try one pass using a matte around the flame (with very soft edges) in transfer and correct the flame area in the shot so it didn't burn out. You'll need to be in a more expensive transfer facility, one that'll do multiple "windows" or mattes, but it's usually worth the $$ if you have the budget. To do this you'll need to keep the flame off the talent or it'll be a nightmare for your compositer or colorist. Don't forget that you can run tape through a davinci (color correction system) or most any film transfer suite and get wonderful results doing a tape to tape transfer/color correction. You might also try shooting the flame as a seperate element all together. Since you'll be compositing anyway, time the flame and make the gag the same length, then put the flash of flame in the shot. Try a test in AE but film will have much more range then tape so this might not work as well with your XL-1. Remember that fire is bright and personally I don't see a big issue with letting it be bright. You may lose detail but take into consideration the big picture. What do you want to say with the shot?? Good luck!
HTH
Wes
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