Two factors that determine the quality of light are its direction or angle to the subject and scene and the spectral quality or harshness of the light source.
Our eyes tend to make up for a lot of the things the camera simply cannot do. Because we have two eyes, we see in "stereo," creating three dimensions, so depth perception is generally not a problem. The camera, with one "eye," does not. And, for the most part, we see details equally well in the shadows of a scene or face as we do in the areas that are lit. Again, the camera does not.
The Angle of Light
In the two-dimensional world of the TV screen, the only way we can perceive depth—the third dimension—is by the shadows present. The shadows or dark areas of the picture convey a multitude of information about the subject or scene. Shadows can let us see the texture of a surface. They can give us the time of day or even the season of the year. They can relate the mood of the situation. They can define the area of main interest within the frame. But above all, they define the space we are seeing.
With the source of light behind the camera and very close to the lens, a scene is almost without shadow. This look is referred to as flat lighting. It is hard to perceive depth, texture, or spatial relationships in the picture. As the light source moves away from the lens, we start to see how the shadows fall both on
the objects creating them (attached shadows) and on their surroundings (unattached shadows).
These shadows are the chief determinant of the quality of light. When any great videographer refers to the quality of light, he or she is talking about the direction of the light or, more simply, the shadows created by it. Flat lighting, lighting with little or no shadows, of an area of a scene or a face within a scene may be desirable at times, but flat lighting an entire scene should be avoided.
Hard and Soft Light
It is impossible to describe the quality of light without talking about both the shadow and its edge: the area of transition between what is lit and what is not. One simple factor determines the difference between hard and soft light: the size of the source in relationship to its distance from the subject. This factor is often referred to as a light's ability to wrap.Hard light is created by very small sources of light as seen from the area being lit.
The sun is an excellent example of a hard source. It may be many times the size of the Earth, but because of its distance, it appears to us as a very small object. The shadows created by it on a cloudless day are razor sharp. As you look at your own shadow on the pavement, you see a perfect outline. Now, let a small cloud move in front of the sun. The sun is no longer—technically speaking—the light source: it is now the cloud. To us, the cloud is much larger than the sun. Now look at your shadow on the ground. It's fuzzy and the shape is ill defined. We now have an example of a soft light source. That fuzzy nature of the shadow is the result of the light wrapping around the object (you). The source is larger than the subject—either wider or taller or both. That defines soft light.
Keep this distance relationship in mind as you go through the rest of the chapter, and certainly when you are on location setting up lights. Lighting instruments that are called soft lights are only soft at certain distances from the subject. A soft light set up 30 feet from the subject is not going to be nearly as soft (have as much wrap) as when that light is 10 feet from the subject.