Lighting Gels

You’re ready with 3-point lighting or a soft-light and mood setting. But what’s missing? How about some red and blue on that dull white scene? Use lighting gels to add some color.

As you prepare for the 4th of July in this politically-heated year, you might find yourself needing to create special lighting for a candidate or an event. There’s an easy way to add some color — be it red, white, and blue or anything else to a scene: lighting gels. Lighting gels are the simple, elegant solution to fulfill all of your color and color-correction needs.

Colored Light

You can add incredible depth and interest in your video scenes just by adding color. When adding splashes of light to backgrounds and perhaps even the backs and sides of your talent, you have to think like a theatre lighting designer. In this case you are not thinking of color temperature or anything dealing with the camera, other than how it will read the colors you use. What you do have to consider, as a theatrical light designer, is the relation between the colors of light you want to use and the costumes of your actors, the color and line of the setting and the overall mood and tone you are trying to create.

Light and color are interesting animals. Color is actually a property of light. You see an object as a specific color because, as the object reflects the light to your eye, only certain wavelengths of light are transmitted from the object, and your brain interprets those mixtures of wavelengths as specific colors. If you want to create a certain color of light, you will use a theatrical gel in front of the light. Lighting gels will subtract from the white light all colors other than the color of the gel. Thus a blue lighting gel creates blue light, and a red lighting gel creates red.

When dealing with color, you have to think in terms of hue, saturation and brightness. Hue is the color itself. In video, the primary colors are red, green and blue. From these three colors, you create all other colors. This is an additive process. For example, when you add red and green light together, you get yellow light. How intense or pure the color appears is its saturation or chroma. A highly-saturated color is very rich. A color that is low in saturation looks washed-out or dull. Finally, how light or dark the color is defines its brightness or value as it might appear in a black-and-white photograph. When you use a reflective light meter, you are measuring the brightness of the light reflecting off an object. The light meter does not see color; it is measuring only the brightness or value of the object. Why go through all of this? When creating a stimulating and dynamic background using colored gels, you must have an understanding of how brightness, hue and saturation will affect the perception of the scene.

The hue of a color is an obvious consideration. Color has a great effect on our emotions. Certain colors seem warmer than others, and some seem to emit a higher energy. Colors that are predominantly red are warm colors. Those that exhibit blue tints are cold colors. Reds and other warm colors add excitement and energy to a scene, while cool colors create a sense of depression. However, it is the saturation that really emphasizes this effect. If a blue is deeply saturated – meaning very blue – it will have a higher energy than a desaturated warm color. Therefore, it is important to understand how both hue and saturation affect the perception of the scene. To achieve highly-saturated colors, you need to use deeply-colored lighting gels, with little or no white light hitting the background. The more white light you add to the scene, the less saturated the colors will be. So if you are going to light a background with colored lighting gels, make sure there is no spill light from your main subject lighting setup.

Finally, you need to consider brightness, to ensure that you have enough depth and contrast in your scene. If the colors in the overall scene seem to be the same in brightness, you need to brighten some of the colors to create a higher contrast and more depth in your scene.

The Theatrical Gel

You can purchase a variety of lighting gels at any theatrical supply house. These lighting gels are similar to the gels used for color correction. Lighting gels such as the Roscolux Medium Red or Fire and Lee Filters’ Primary Red or Medium Red provide intense, deeply-saturated red light that can add a splash of energy to any scene. If you want to create a splash of cold blue across your industrial set, you might consider the Roscolux Primary Blue or Sapphire Blue or Lee Filters’ Just Blue or Dark Blue. To create the light from the moon, you may want to use a double CTB (Color Temperature Blue), the common color-correction gel, or Lee Filters’ or Rosco’s Sky Blue. Rosco sells these gels in sheets of 24×25 inches or 50-foot rolls of 12 inches. Lee Filters gels come in rolls of 25 feet by 48 inches or in 21×48-inch sheets. Call your local theatrical supply house for pricing and swatch samples.

Using Lighting Gels

Always place your lighting gel in a gel frame. Do not place gels directly on the face of the lighting instrument. Although gels are made of heat-resistant plastic, they do melt, and you will have a mess on your hands if there is not a small space between the gel and the light to let the heat escape. Most lighting instruments have specially-designed gel frames that clip or frame the gel. Place the gel in the frame, and make sure that there is very little or no spill light sneaking around the edges. Remember, even a little bit of white light will desaturate your color and turn your deep reds into washed-out pinks!

When setting up your background lights with colored lighting gels, think about what you are trying to accomplish. Light, just like set pieces and movement, looks better if it is slanting diagonally across the picture – not straight across. Use barn doors to create a slash of blue and a slash of red during your political rallies. Throw a deep color across background pieces, giving them more depth and detail. Use your imagination. If you need depth in the frame, adding deep color to the background will provide interest and give your background a three-dimensional feel, especially when the color wraps around objects. Always remember to flag any white light from falling on the areas that are being lit by colored gels. Otherwise, the colors will become desaturated.


Make Sure You White-Balance!

We all know that, when a camera sees white as white, the rest of the colors in your shot should be correct. However, what if you are using colored gels? Remember, if you are using a blue gel to create bluer light, you actually want to see it as blue. If you white-balance under the blue light, the camera will think it is white light, and it will turn everything orange. When using colored lighting gels, always make sure you are white-balancing with the white light that you are using to light your talent. If you want to light your talent in blue light, to look as if they are walking through moonlight, then you must remove the gel, white-balance and then replace the gel.

Color-Correction Gels

While there are more than 30 color-correction gels you can use to change the color temperature of a light source, they all fall into four major groups: CTO, CTS, CTB or Plus or Minus Green.

CTO, or color temperature orange, is a gel that you can place over windows to convert outdoor 5600K light to indoor or 3200K light. In other words, it strips the blue out of the outdoor light so that it will match the color of the indoor light.

CTS stands for color-temperature straw. This gel has the same function as CTO, except that it is more yellow and less red. This provides a little cooler color for outdoor light.

CTB, or color temperature blue, converts 3200K indoor lighting to match the 5600K light coming through the windows. This is a very effective gel that enables you to use outdoor light as your base light, while you use a 3200K instrument gelled with CTB as your key light.

Finally, Plus and Minus Green gels are used to color-correct fluorescent lights. The Minus Green gels are magenta in color. They strip the green out of the fluorescent light and match it to indoor or 3200K light. If you find that you are spending a lot of time shooting in offices with fluorescent tubes, you may want to buy tubes of Minus Green that fit over the fluorescent fixtures.

Neutral Density

One final word on lighting gels: If you are using CTO or CTS on Windows, you will probably still need a neutral-density filter to decrease the level of light coming through the window. Outdoor light is much brighter than indoor light, and the neutral-density gel reduces the light coming in without changing the color temperature of the light. Conveniently, gel manufacturers have combined the CTO and CTS gels with neutral-density gels, so that you can actually use one gel to accomplish both color correction and light intensity reduction. Your windows will look like they have a brown glaze, but the camera will see only the beautiful green grass and blue skies that lie beyond the windows.

Contributing editor Robert G. Nulph, Ph.D., is an independent video/film producer/director and teaches video production courses at the college level.

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