AN INTRODUCTION TO LIGHTING FOR DIGITAL FILMMAKING - page 2

To discuss basic equipment and techniques, we need to agree on a few terms, which I'll present first. Standard terms will allow us to communicate more effectively with each other. We'll focus on how they apply to shooting DV. Rather than get too wrapped up in detailed definitions, I'll only present what needs to be known at a high level, and I'll include more detailed definitions in the appendix. If a definition seems too vague, check in the back of the document to see if more information is available there. Finally, most of the time when I use the term CCD (Charge Coupled Device, the part of a video camera that converts light into an electrical signal), I could have used "film" if we were talking about film instead of video.

The quality of light can be "hard" or "soft." A hard light casts sharp shadows. The most spectacular hard light is the sun. Other hard lights are arc lamps, candles, and undiffused lights of many types. See the appendix for more information.

A striking example of hard light is the lighting used in Dr. Strangelove. In one scene, General Jack D. Ripper (Sterling Hayden) is smoking a cigar and talking about precious bodily fluids. The fast falloff of the shadows on his face makes him look more rugged and threatening. If you have not seen this film before, GET UP FROM YOUR CHAIR RIGHT NOW and see it.

A soft light casts soft shadows, or no shadow at all. An overcast day produces soft light. Soft lights are employed in film and video because that are often more flattering because of the softness of the shadows. The slow falloff of shadows can hide facial lines and wrinkles. Soft light was used conspicuously on many, many Hollywood starlets from the 20s to the 50s. See Some Like It Hot, as an example. Any time Sugar Kowalczyk (Marilyn Monroe) is on-screen, she is bathed in soft light.

The light that you will use to shoot with comes at different color temperatures. The two numbers you should learn are 3200K, which is the temperature of most professional tungsten film and video lamps, and 5600K, the temperature of HMI lamps (more on these lamp types later), and is regarded as "daylight." Ordinary incandescent light fixtures in your home are redder still, operating near 2800K. See the appendix for more information.

Why do we care? Because we need to be able to use light sources of various temperatures. For most purposes, you want to match the color temperature of the light sources, so that you don't call attention to the light instead of your subject.

The physics part of the paper! With math! The Inverse Square Law is a fancy way of saying that if you put a radiating body, for example, a light or a microphone, one half closer than before, then the intensity of the radiation will not be double, it will be four (2 squared) times more intense. This is useful when lighting because it means that you can make significant adjustments to your lighting simply by changing the distance of your lights to the subject.

The aperture (or diaphragm, or iris) part of a lens assembly that controls the amount of light that reaches the CCDs that records the image.

Stop numbers are marked on better camera lenses, as "2, 2.8, 4, 5.6, 8, 11, 16" and usually a lower number, depending on the "speed" of the lens. Each of these stops indicate that twice the light is transmitted than the stop above it. For instance, stop 4 transmits twice the light as stop 5.6, but only half of what stop 2.8 transmits. Why the weird numbers? Because it's the ratio of the focal length of the lens to the size of the aperture. For example, a 50mm lens with an 25mm aperture setting will be at f/stop 2. (Note that I typed this as "f/stop" instead of "f-stop" to highlight the fact that this is a ratio. See the appendix for more information.

A lens works by focusing light. One focal point is on the CCDs and the corresponding focal point is in front of the camera, where the subject is. There is a "depth of field" before and behind the focal point. This can be shallow or deep, and is determined by the distance to the lens and the aperture size. A small aperture gives a very deep depth of field, like with a pin-hole camera, which is trivially easy to focus, but gives images that are not very varied or dramatic.

This isn't a camera discussion, but because this comes up a lot, I'll explain briefly why video camcorders don't have as much depth of field as 35mm or 16mm cameras. Simply, it's because the CCDs are so small. Rather than go into a long discussion, you'll have to trust me when I say that the bigger the imaging area, whether it's CCDs, the greater your ability to control the depth of field. Prosumer cameras (the ones that we can afford) have 1/4th or 1/3rd inch CCDs. That translates to about 8.5mm. Professional camcorders have 2/3rd inch CCDs, but it's still not as good as having 35mm to play with.

The duration that the shutter on the camera allows the light to reach the CCDs. The shutter opens, letting light in and the longer it remains open, the more light reaches the CCDs and the brighter the recorded image will be. Slow shutter speeds such as 18 fps (frames per second) requires less light for exposure than a faster shutter speed such as 24 fps because the light is allowed more time to illuminate the CCDs. This means that at slower shutters speeds, fast motion will appear to blur more for the same reason.

The image that is captured on the CCDs, which is a function of the shutter speed and the aperture size. You can underexpose to make an image darker and overexpose to make it brighter, and each changes the depth of field of the image, not just the brightness.

Light that falls onto an unintended area

The ability of light to make something look more three-dimensional, by controlling the quality of shadows.

A note about terms. Ross Lowell, the lighting inventor and cinematographer, coined the phrase tyranny of terms, and this refers to the tendency of terms to turn into dogma. One advantage we self-taught people have is that we aren't tied to such a rigid structure as people that are on the "inside." All that matters is the ability to make yourself understood. Don't sweat the little stuff.