The Ability to See Light as Your Camera Sees It Puts Quality Control In the Spotlight
With fast lenses and sensitive imaging devices, today’s video cameras can record a picture with virtually no light at all. All you have to do is aim and record. So, why light for a video camera?
Indeed a tribute to advanced electronic technology, the video camera can do many things. But engineers have not yet found a way to make it “creative.” You do that. If you want more than basic lighting in a scene, you’ll need to do some creative planning.
Here’s the Story
Creative lighting makes a story interesting and entertaining to the viewer. Lighting helps establish the mood that tells the story, just like words, action, music, and other elements-not lighting just to see objects in the shots, but lighting to help the viewer understand the story.
It might be about your vacation, your baby, your new house, or your niece’s wedding. It might even be a story about how to do something. Some stories are interesting, some are boring, and some can be downright bad.
One cause of the latter is bad lighting, often attributable to the fact that light is so prevalent, most of us don’t see it. If we want more, all we do is flip a switch or open a drape. And if we can’t add more, our eyes will adapt to the available light.
A camera can’t do that, at least not to the same extent our eyes do. In fact, the video camera can’t even see as much as a film camera under the same lighting conditions.
Video cameras that will record a picture at 3 to 5 mx (light measurement indicating lumens in square meter) will make much better pictures at 1400 to 2800 lux, an ideal amount of light for most cameras shooting indoors.
Okay, if you are going to light creatively, you must learn to work within the restraints of the video system. All it takes is a little knowledge and practice, plus learning to see light. You want to see light as the video camera does, not as your eyes do.
Learning to See Light
We see objects three-dimensionally, while a video camera sees two-dimensionally. A TV picture lacks depth; it’s flat, especially if improperly lit. What adds shape, depth, and texture to the picture are the shadows, darker areas contrasting the brighter ones.
o see as your video camera does, hook it up to a monitor. Then compare what you see to what the camera sees.
To see the difference shadows make in the TV picture, set up a ball or other round object so that you can get a good closeup with the camera on the same plane as the ball.
Now light directly behind and a little above the camera so it does not block the light beam focusing on the ball. With this setup, the ball will resemble a hockey puck on your TV.
If you move the light about 45 degrees left of the camera, you’ll see a shadow on the right side of the ball, which will start looking spherical. If you elevate the light a couple of feet, you will cast a shadow on the right side and bottom of the ball. Now, it really looks like a ball.
Seeing the ball on tape with the light in the first position, your audience probably would have thought you were showing a hockey puck. Of course, you could have revealed it was a ball with narration or titling. But if you light correctly, the audience will know what it’s seeing without explanation.
Here’s a simple technique to help you see like your camera: Close your eyes until you can see 50 percent of what you normally see, then block your peripheral vision with your hands to frame the shot. You will see approximately what your camera will record.
The video system is limited by the amount of light and by the contrast ratio-the brightest part of the shot compared to the darkest.
When you exceed this limit your pictures will have noise. Those black, white, and colored specs running all over the screen are actually the system recording its own electronics. The maximum contrast ratio a video system can handle is about 30:1, although most broadcast lighting directors will not exceed 20:1.
To determine the contrast ratio, use a light meter to measure the amount of light in the darkest then brightest areas of the shot. The light meter readings can be taken reflected or incident, and it makes no difference if the increment readings are in footcandles (fc), lux, exposure values (EV), or f-stops.
As an example, if the darkest area is 16 fc and the brightest is 260 fc, the contrast ratio is about 16:1, calculated by dividing the smallest number into the largest.
If the light meter reads in lux, the same footcandles would be about 175 and 2800 lux respectively. If it reads in EV, they would be 11 and 15; and fstops would be five stops. Every fstop or EV doubles the light of the previous one; 11 lux equals approximately one fc.
Contrast ratio has nothing to do with total amount of light, only the difference between the least and most in a shot. If the brightest part of the shot is in the direct sunlight, the light meter reading can be 16,000 fc while the shadow reads 500 fc.
This 32:1 ratio indicates too much contrast for the camera to record the scene properly. To solve the problem, bounce more light into the darkest area with a white board or other reflective surface to increase the fc reading.
On the other hand, if a manufacturer says its camera will record a picture in 7 lux, less than one fc of light, the maximum light you can use on the brightest end is about 210 lux or 19 fc.
Forecasting Color Temperature
The light’s color temperature is another important factor in lighting for a video camera, although not as crucial for some newer models.
The newer white-balance circuits do a great job of making colors true under mixed color-temperature lighting conditions. But you will still get the best color rendition under all natural light or all artificial light.
Without getting too technical, here’s why the color temperature of light is important to the video camera.
Color temperature is measured in degrees Kelvin (degrees K). The lower the degrees Kelvin, the more red the light will appear to the camera.
Most TV lighting instruments yield 3200 degrees K, while natural light is generally considered 5600 degrees K (the actual degrees K changes constantly relative to the sun’s angle as well as atmospheric conditions) or more blue.
he standard calibration for all video cameras is based on 3200 degrees K, the correct mix of the visible color spectrum of light to make white light.
When your camera is white balanced, it has balanced the video voltages to the correct amount for all colors-red, blue, and green-seen on your TV screen.
With part natural and part artificial light in a shot, some cameras don’t know which light they should white- balance to, causing some strange-looking colors, particularly with flesh tones. Obviously, this situation is corrected by using all natural or all artificial light.
But, as we all know, this isn’t always possible-especially true when videotaping indoors where there are windows. The household lamps will be about 2000 degrees K (more red) and the light coming through the window can be 5600 degrees K (more blue) or more.
Since the natural light will probably dominate, it makes sense to try to bring the artificial light to 5600 degrees K, making it more blue. Covering the artificial source with a blue gel or piece of blue cellophane can reduce the amount of light it emits by about 50 percent.
Of course, you can also close the drapes to eliminate the natural light, but if you use only household lamps, your pictures might tend to be too red depending on your camera’s white-balance capability.
Using lens filters to correct color balance generally isn’t effective. When you absolutely cannot change all the light to one color temperature with gels or lamp replacements, try fooling the camera’s white-balance control: Show the camera a card of a different color while pressing its white-balance button.
For instance, if you want the pictures to be wanner (more red), white balance with a cyan-colored card. Thinking it’s seeing white, the camera will add the red to compensate for the blue/green color it’s actually seeing.
This technique works in most circumstances, but do some testing before important recording.
Lighting Tools for the Task
There are basically two types of lighting instruments: spots and floods.
A spotlight produces a well-defined paralleled beam of light, and casts hard, well-defined shadows; the reflector is generally a polished, smooth surface.
A flood light provides a diffused light and soft shadows; the reflector can be a rough surface of either metal or fabric, sometimes in the shape of an umbrella.
Some instruments are fixed focus, meaning that the light beam will be a specific size and brightness at a given distance. Other types allow you to focus the beam from wide to spot.
Dimmers that help you control the amount of light should not be used if the color in your shot is critical. Reducing the voltage to the lamp lowers color temperature at the same time.
Lighting instruments made especially for video cameras are your best resources for artificial lighting. Some operate with regular household current and others from batteries; some even work with both for optimum flexibility.
Generally,the type that mount on the camera provide harsh illumination not conducive to creative lighting. Most professional lighting is done with the lighting instruments mounted on light stands or, in a studio, from an overhead grid.
Several companies offer assorted lighting kits packed in cases about the size of a large suitcase. These generally will include all of the lighting instruments, stands, gels, and other hardware needed to do a good lighting job.
Your choice of video lighting accessories should reflect the kind of shooting you plan to do. If you decide to invest, make sure the lights are rated at 3000 to 34000 degrees Kelvin.
The Setup: It’s Your Show
People will tell you you must do this or you should always do that. But the only true necessities when lighting for a video camera are: Stay within the video system’s technical limits, experiment, and when you find what works for you, do it.
Lighting is creative as well as subjective. What you see in your mind is completely different from what someone else sees. Even when looking at the same videotape, we see it differently.
One basic goal to keep in mind when lighting is to help the audience understand the story you are telling. Two television shows come to mind that do this very well.
Miami Vice uses dramatic lighting to strongly reinforce other story elements.
The words, action, and music would be less effective on this show if the lighting was as it is on LA. Law, which floods locations with light to make them look like real offices and courtrooms.
These shows tell different kinds of stories with different moods and motivation, but they both have one thing in common: The lighting helps you understand the story. The light is where it should be, coming from the logical directions, and creating just the the right shadows and textures.
Keep in mind, we are used to having light come from overhead. So when lighting for video, the light source should be higher than the camera.
If you don’t know where to start your lighting setup, two good rules follow.
First, start at the back of the shot and work your way forward. When you are finished lighting, you should be able to walk right out through the front door.
Sounds simple, and it is-which leads to the second rule: Keep it simple. Do not use more lighting than you need to create the look and mood you want.
So, if we are to follow these two rules, the first thing we need to know is where the back of the shot is. We already know where the front is; that’s where the camera is.
But will the camera always be in just this one location? Maybe you’re going to move it around or you’ve decided to put it on your shoulder and walk around to get the shots. You must decide before you start setting up the lights!
The next consideration is the mood you want to convey. For your grandmother’s interview as part of a “video family tree,” the desired mood could be a nostalgic one.
In this case, you’d do well with low-key lighting, commonly used for more dramatic scenes. The effect is defined by the lighting ratio (not to be confused with the contrast ratio), the difference between the key light and the fill light.
The key light is the major source of illumination for the main person or object in a shot. The fill light softens the shadows made by the key.
Generally the key light is placed on one side of the camera and the fill is on the other at about half the power of the key, or twice the distance from the subject. The fill light should never cast its own shadows.
Highs and Lows
An example of low-key lighting would be where the key light is providing 200 fc and the fill about 25 fc, alighting ratio of 8:1.
With this type of lighting, the background is of lower intensity than the rest of the shot. But don’t forget to throw some light on it; even the unimportant parts of the shot must have some light reflecting back towards the camera to avoid noise problems.
If part of grandmother’s trip down memory lane includes photographs hanging on a wall, you’ll want to light them separately. The lighting for flat photos is called flat, or zero contrast.
You set up two lights, one on each side and equal distance from the photo at about a 45-degree angle to the front. To see the texture of an oil painting’s brush strokes, move the light on one side two or three times the distance from the painting as the other one.
If you want to sell your audience something, convince them your way of doing things is the right way, or just show baby’s first steps, high key lighting would be most appropriate.
High-key is where the lighting ratio is about 2:1 and not more than 3:1. The mood you’re trying to achieve is an open, straight-forward one-communicating to the audience you have nothing to hide.
One last word about lighting ratios:
If you shoot your video out of sequence, make sure your lighting ratios match from shot to shot. Seeing two shots of the same person in the same location from a different angle edited together but not matching can be disturbing.
One More Ratio
You can think of exposure ratio as the lighting ratio, but on a larger scale-the total area the audience will see in the widest shot of any scene.
Exposure ratio is important because you are establishing a mood with the high-or low-key lighting on your video’s main subject. It’s difficult for the audience to understand a high-key lighting setup in the foreground with low-key lighting in the background unless you are doing it for some special effect.
You measure exposure ratio the same way you can for the lighting ratio, but also turn off the background lights plus any other lights that aren’t keys or fills for the people in your shots. Then you reverse the procedure to take the second measurement.
Generally, the background lighting should be brighter for a high-key setup than for low-key, In both setups the exposure ratio should be about the same or a little lower than the lighting ratio.
Remember that lighting is reflected from the people or objects in your shots, but results should be a reflection of your own bright ideas.
James Caruso and Mavis Arthur have produced more than 600 TV shows and commercials for broadcast, corporate, and instructional use. The duo has written three books on television production soon to be published by Prentice-Hall.