A brief discourse on the behavioral patterns of the common video microphone.
Greetings, students. During this class period we'll be taking a closer look at the sometimes peculiar characteristics of Microphonicus Videus, or the video microphone. A solid understanding of how mikes interact with their environment will aid you in your dealings with these creatures, and will help you apply them toward better-sounding video productions.
Mikes Don't Concentrate Well
When using your first camcorder, you were no doubt impressed with the ability of its lens to zoom in on a distant subject. Some camcorders have optical zoom ranges that make them work almost like a telescope, focusing attention on a very small area. Unfortunately, microphones don't work this way. Because of the way sound behaves, no mike can concentrate on a subject the way a lens can. Even a highly directional shotgun mike (with a long, slender barrel) picks up sound over a roughly 60-degree swath. Compare that to a zoom lens' ability to hone in on just a few degrees worth of real estate in front of it. Even so-called "zoom" mikes pick up sound over a relatively broad range.
The most common microphone pickup pattern is called "cardioid." Its pattern is roughly heart-shaped if viewed from the side of the mike. This type of mike is dramatically less directional than a shotgun mike, picking up sound over an angle of roughly 130 degrees. In other words, the average microphone is picking up sound at an extreme wide angle setting all the time.
Imagine if your camcorder had no zoom lens, and was always shooting at a very wide angle. If you wanted to reveal the details of a painting, show the viewer some text on a sign or get a good look at someone's face, you'd need to move the camcorder very close to your subject. Only then would your subject fill the screen. So it is with the microphone.