Great sounding audio is key when producing a high quality video. Using a good microphone is one of the most important things a filmmaker can do to improve the audio quality in their film. It’s also key to get the microphone as close to your subject as possible.
The first part of our new series on basic audio techniques for video will explore some of the basics of using a boom microphone during a video shoot.
Built-In Camera Mic vs. Shotgun Mic
A camera’s built-in microphone is lower quality, has less reach and a much wider angle of pickup. This means you will be picking up more of the surrounding noise in your environment and less of the voice you’re focused on.
Replacing the built-in microphone with a shotgun mic like the AT897 will vastly improve the quality of your audio. Because this microphone is monaural as opposed to stereo, it’s far more directional. This provides much less ambiance and your actor’s speech will come across much clearer.
Properly positioning your shotgun microphone is vital for capturing quality audio. While zoom lens can record your actors from as far as a football field away, most shotgun microphones can only capture perfect dialog from a fraction of that distance.
The most expensive shotgun mics can only capture audio from a distance of six to ten feet, while more affordable mics sound their best at a distance of three to four feet away.
Interviews are typically shot from about seven to ten feet away from the subject.
Booming from Above
The best sound will come from positioning the shotgun mic a few feet above your subject. The camera can be any distance away, but the microphone will remain close enough to the subject that you can hear dialog crisp and clear. This provides audiences with the intimate performance they’ve come to expect.
When booming from above, the microphone will be pointing downwards. Noise from around the room will strike the sides of the microphone, where pickup is much less sensitive. Dead side pickup is referred to as off-axis.
At the same time, dialog is being picked up on-axis under the front of the microphone, where the mic is the most sensitive. This provides us with less ambient noise and more emphasis on the vocals.
Dynamic mics like the BP4002 and AT8004 are often used by field reporters and only react to moderately loud sounds that are close to the microphone. For conversational purposes, the microphone is typically held four to eight inches from the subject.
This type of microphone wouldn’t be ideal for suspending on a boompole, as the goal for most film shoots is to keep the microphone out of the shot.
The Importance of Perspective
Keeping your microphone off the camera and attaching it to a boompole or mic stand is important when using different camera angles.
Every time the camera pans or tilts the on-camera microphone changes direction as well. This creates a change of perspective of your audio, especially if it’s being captured from a fixed source or direction. This can be remedied by simply mounting the microphone on a tripod or mic stand. This allows your audio to remain constant during filming, regardless of how often the camera moves.
In the studio or on location, these tips will have you capturing audio like the Hollywood pros.