Tinted gels, correct white balance, and correct Lighting for digital video can make the different between professional and amateur quality.
Who needs colored lighting for your video these days, since your digital post system lets you dial in any hue you want? Digital color filters let you do some amazing things, but they can look, well, digital. There is still no substitute for soft, natural-looking, colored light in digital video production. Pros use color media all the time to correct color temperature problems, to enhance the lighting on subjects and to simulate off-camera light sources. We say color media, plural, because light shifters come in several flavors: glass filters, gel filters and tinted plastic tubes.
Glass filters drop right into the barndoor rings of spotlights. Effectively heatproof, they're a set-and-forget convenience and should be in every lighting kit. Gel filters come in two main types. (By the way, their remote theatrical ancestors were indeed sheets of tinted gelatin, but modern gels are heat-resistant plastic.) Small gel sheets are used in front of both spots and floods. Big sheets, some big enough to cover picture windows and sliding doors, are mounted on frames or applied to glass surfaces. Finally, fluorescent lights can use specially designed tinted plastic tubes. We'll talk about when and how to use these various types, but let's start with what to use them for.
Lighting Digital Video in the Great Outdoors
The most common use of color media is for correcting light sources that mess up your white balance. When used outdoors, naked movie lights (3200K) are much too orange to mix with sunlight (around 5000K) and if the sky is overcast (maybe 6000K) fuggeddaboudit! Fortunately, you can easily convert your lights to outdoor color temperatures with glass media called dichroic filters. These strange-looking bluish/orangish/silverish (really!) filters not only change the color temperature from indoors to out, they also help dissipate heat before it reaches the subjects under the lights.
Chances are, though, you don't have the crew, lights and generator to deploy studio units outdoors. But what about battery-powered mini-lights? An on-camera light is invaluable for punching up the brightness on a face, say, when you've positioned your subject to use the sun as a back or fill light. Most camera-mounted lights can be gelled, and some models have gels hinged to the light so you can swing them in and out of the light path.
Useful as they are outdoors, gels really come into their own in interiors. The most common indoor color problem is mismatched light sources. The color temperatures of window light, fluorescent light and incandescent light are all different and not one of them exactly matches the 3200K of movie lights. It's very common, for example, to find a classroom or office with both windows and ceiling fluorescents just waiting for you to complicate the problem even further with your much warmer movie lights.
If you haven't enough movie lights to simply mask the windows and switch off the ceiling grid, you'll need to gel one or even two light sources to achieve a uniform white balance. The simplest plan is to break out the dichroics and convert the movie lights to outdoor color temperature.
If the overhead fluorescents are high quality and recently installed, they may be close enough to mix with daylight, but usually they're not. One solution to the problem is to re-lamp the entire ceiling with 5000K fluorescents, which are widely available. But they cost ten bucks a pop and a full kit of them leaves you with a lot of glass to shlep around.
Instead, you can use gel media specifically colored to convert office-grade fluorescents to outdoor color temperature. Fine, now your movie lights and your ceiling grid match the white balance of the sunshine streaming through the big windows.
But wait: suppose you want to work mainly with movie lights, say, using the grid just for extra fill and the window for background lighting? Instead of raising the bridge, try lowering the river. First, whip out your other set of fluorescent gels that converts them to indoor color instead of outdoor. Then cover all the windows with orange gel sheets that convert daylight to 3200K. Set your camcorder's white balance for indoors and you're ready to rumble. Matching mixed light sources is such a common chore that pros generally carry the filtration needed to correct in both directions.
Even when you've matched all of your lights, you may want to tint just part of your image. For example, a pale yellow gel on a back light spot will splash a warm and flattering sprinkle of gold on your subject's hair and shoulders.
Using pale, subtle tints, you can gel key and fill lights to fix complexion problems, enhance skin tones, or simply add a studio look to your lighting design. This works well with on-camera spokespersons, especially women. For instance, instead of making her change that lipstick that looks Munsterish on video, you can use gels that actually complement it.
For digital video lighting in studio setups, tinted lights work great on dull backgrounds, even the drapes so often used on inexpensive shoots. To make them work, check the overall color scheme of the set and then punch it up with complementary splashes of light. For variety, try using cookies (patterned cutouts on stands) in front of the background light to break up the light and add interest.
Will Ya Look at That Moon?!?
Like sound effects, off-camera colored lights are an easy way to imply things that don't really exist and, when artfully combined with audio, this type of son et lumire show is dynamite.
Moonlight, or at least exterior night-light is easy to fake with blue gels, as long as your white balance is on the indoor setting. Working outdoors, you can use a dichroic-filtered light (off- or on-camera) to enhance day-for night shots. (For more on day-for-night shooting, see the July 2001 issue.)
Going in the other direction, pale yellow gels can simulate old-fashioned lanterns and orange gels make great off-screen fires. To help sell the gag, cut a hula skirt out of newspaper, staple it to a long stick and waggle it in front of the orange-gelled fire.
Digital Video Lighting:The Scene
Now let's put all this together. Suppose you have a scene in which the young campers sit around their campfire while the counselor scares the bejabbers out of them with ghost stories. You have location establishing shots of the group, but the real fire is too hard to work with and the performers' parents want them home before ten. You'll have to make all the two-shots and closeups in a studio.
To start, hang a black drape far enough back so it will be beyond the light spill and out of focus. With the kids seated, place a spotlight gelled orange as close to the floor as possible, with a crewmember to hula the dancing flames effect. That's the key light. Set up blue-gelled fill and back lights, with the fill light higher than normal. Using an unfiltered movie light, set the camcorder white balance manually (so it won't struggle to whiten the "fire" light).
Now, framing off the floor, record the sequence as many times as necessary, each time with a different kid (or pair of kids) in front of the black curtain. If you keep changing the relative positions of the blue fill and back lights, the audience will never know that all the actors, in turn, were taped sitting in exactly the same spot.
In post, lay in crickets, a hoo! hoo! owl effect, and maybe some spooky branches cracking in the distance. Intercut the studio and location wide shots and you've got your sequence.
Using Gels When Lighting Digital Videos
We've already described glass filters. Some gel plastic is so tough that you can fit it into rings that also drop in spot light holders. Larger floodlights will safely accept sheet gels. With fabric soft boxes, gel the light source inside. To keep the gel away from the heat, you can clothespin a larger sheet to the spread barn doors of the light, or else hang the plastic on a century stand (c-stand) placed in front of the light.
Fluorescent filters are easy to use: remove the tube, insert in filter sleeve and replace tube. These tools can be pricey though, so you may want to sheet-gel just the ceiling areas that throw most of the light on the shooting space.
Window filters can be very tricky. Big production crews rig frame-mounted gels outside the windows; but even if you have the resources, you can't do that on the 22nd floor. It's easy to hang gels inside the windows, as long as the camera never sees them. If a window will be in a shot, it needs gelling with the type of clinging film used to smoke auto windows a finicky process that must be carefully done to avoid bubbles and distortion.
One final note: since outdoor light is so much brighter than indoor, you can knock it down by using window gels in which the color tint is combined with neutral density gray. For example, a gel coded "85ND6" combines both a daylight-to-tungsten color with two f-stops of light reduction.