Color Temperature Strategies
Coloring your video world with light is more than just turning on a few lamps and setting a good white balance-light is often a mixed bag.
When you're lighting a shoot you're responsible for color temperature. Sure, videographers set the camcorder white balance, but they can only work with the light you give them; and in real-world production, that light is rarely the nice, clean 3200K temperature that makes the camera smile. You usually face a mixture of incandescent and fluorescent light, or either (or both) fighting window light. And that window light is anywhere from 5000K all the way up to nine and change. This would be no big deal if all the light sort of blended into a compromise color temperature, because the camcorder can be set for a wide range of nominal "whites".
But light doesn't do that, so there you are preparing to tape the CEO in her executive office, with a halogen spot for a key light, a huge window for fill, and a fluoro ceiling for rim and background lighting. Great: one side of the CEO is orange, the other side's blue, her hair is edged in green, and her priceless rosewood walls look like limed oak. What's a poor gaffer to do?
Plan ahead, for starters, beginning way back before your first lighting job.
Choose Your Weapons
Before you even assemble your lighting kit, decide whether to go with halogen or fluorescent lights. That decision will determine whether your native lighting temperature is 3200K or 5000K (+/-). (Indoor color fluorescents are also available, but for simplicity we'll focus on the more common outdoor types.)
In making your decision, consider two big factors: the pros and cons of each lighting approach and the kinds of available light you're most likely to find at the locations you frequent.
Halogen lights are lightweight, compact, and powerful. They're available in spotlight and broad flood designs that allow precise control of beam size, shape, intensity, and fall-off. Without doubt, they are the most flexible, versatile lights you can use. On the down side, halogens are hot and they're power pigs. The popular 1,000 watt size sucks nine amps, so just two of them will blow a 15 amp household circuit.
Fluorescents are exactly the opposite: they sip power sparingly, and because of this electrical efficiency, they pump a lot of light per watt and they never get dangerously hot. But fluorescents work only for soft lighting, usually as pan lights. (As yet there is no such thing as a fluorescent spotlight, although screw-base fluorescents are now available, as the sidebar explains.) Because most units contain multiple tubes, fluoros are big, heavy, and clumsy, even though ingenious vendors like Lowel have done wonders in minimizing their bulk.
So, if you need small size, portability, and lighting finesse, consider halogens. If low heat and power are important, look at fluorescents.
But wait, there's more. If you work in a school, an office, or any public building, nearly every location you shoot in will be lit by a fluorescent ceiling grid and most likely windows as well. Fluorescent video lights will be a close match to the light already available at the scene -- a very good reason to choose them for your basic light kit.
On the other hand, if you're working high-quality professional productions, you may routinely disable all ambient illumination and light exclusively with video lights. Since you won't have to match cool ceiling or window light, you won't care if your versatile, powerful halogen instruments emit a much warmer light. So: step one is to standardize on a halogen or fluorescent light kit.
Color Temperature Conversion
Step two is to lay tools in to cope with the ambient light at locations, so that all light sources are the same color temperature. You have three options here, and you may choose to use more than one at a time.
The first choice is to convert your video lights to the prevailing color temperature. To match daylight, direct 3200K halogen light through a series 80 blue filter. To sync with ambient incandescent light, cover 5000K fluoro pans with a series 85 orange filter.
Your second option is the exact opposite: to convert the ambient light to match your halogen video lights. Windows can be gelled with large sheets of that same 85 orange filter (more on that later). Ceiling fluorescents can be sheathed in orange tube. In some cases, it's easier to place sheet filtration over existing fluorescent fixtures.
Finally, you can swap out the existing lamps (if not the daylight). Movie-grade tubes are available -- if a bit pricey -- and now you can obtain medium (household) screw-base "curly" fluorescents that will replace most light bulbs in practicals (lamps and such that are visible in the frame). See the sidebar for more details.
When you arrive at a lighting location -- or better yet, when you scout it prior to shooting -- you can start down a color temperature decision tree. First, do you or don't you want to use the ambient light?
If you don't, your decision's made. Turn off the room lights, curtain the window (or mask its light with mover's pads held up with century stands) and start lighting.
If you do want to use ambient light, the next decision is how to handle it: use it, filter it, or change it. With daylight, your options are to use it or filter it. If you use it, you'll want to filter other sources (available lighting and/or video lights) to match.
If you filter it, you'll need to frame off the window, because window sheet filters look obvious unless they're rigged outside -- a complicated job and nearly impossible if you're above the ground floor. As long as the window stays out of frame, you can use its light, filtered through an 85 gel.
If your big light source is overhead fluorescents, run a manual camcorder white balance set and then check the image on the monitor. If the result is still greenish or chalky, consider abandoning the ceiling grid, replacing its tubes, or gelling it.
Often, you'll find that the ceiling grid and the window light are close enough in color temperature to yield pleasing images. In that case, go with your fluorescent video lights, or use blue gels on your halogens.
Whichever way you decide to go, the key to a professional look is color temperature that's reasonably consistent throughout the shot, whether the light is from windows, fluorescents, or halogens. For warm, cool or neutral lighting setups, when you know the tricks, you can color the world.
Jim Stinson is the author of the book Video Communication and Production.
Sidebar: Today's Fluorescents
Today, you can buy fluorescent tubes in any hardware store that mimic outdoor light with tremendous accuracy. You can identify them by consulting the laminated tube guide usually provided at the tube display.
Medium screw base curly lamps are widely available too, but their color temperature is highly problematical -- ranging from shop light-marginal through barfo green.
However, there is a source of 5000K screw-base lamps suitable for video work. Check out The Equipment Emporium (www.equipmentemporium.com) and look at their "Fluoro Lites". These lamps burn 26 watts and put out the equivalent of 125 incandescent watts of light. That's great for replacing practicals, but skimpy for movie lighting; so they sell a scoop-type instrument that takes three lamps. Add a little diffusion and you've got a 78-watt soft light that puts out 375 watts of light.