Many people, even people in the commercial production business, assume the microphone at the end of a boom pole is called a shotgun. First lets start with what a shotgun microphone is and when it is used and it’s drawbacks.
A shotgun microphone is an extremely directional microphone used to record dialog and ambiance from a distance of more than a few feet and generally in an outdoor location. There are two types of shotgun microphones, long and short. A short would be used in the majority of situations outdoors, the long when boom needs to be more than 10 feet away. Probably the most popular microphone for commercial production ever is the Sennhieser 416 short shotgun. Developed in the 60s it’s still often the go to microphone for a outdoor dialog.
Shotgun microphones like the 416, although great a rejecting noise from the side, generally suffer from two drawbacks: susceptibility to reflective noise – echo and proximity effect. Echo mainly becomes a problem indoors with these microphones, because they’re designed to work at a distance they’re tend to pick up sound waves as they bounce around interiors. Acoustic reinforcement will often help but in most cases it would be better to just use another microphone.
Proximity effect is something some VO guys use to their advantage, when they want to create a booming dialog, you know, the “In a world where…” schtick. Basically the design of directional microphones, the more directional they are, the more them emphasize bass sounds the closer they are to the source. This can be bad for location work if you want someone to sound natural and not change in tone throughout your picture.
So what do you do? Well, microphone designers have created other pickup patterns to deal with these issues, just like there are lenses to deal with different distances and shooting situations, so are there microphones.
For closest microphone placement distances an omni pattern microphone is used. This is often the type of microphone you’ll see a TV presenter carrying and has a circular pattern, meaning it pics up sound in all directions. Most lavaliere and “plant” microphones are also omni. It’s very forgiving pattern as long as it’s close to your source.
For use a little further away, and often used in interviews, is a cardioid pattern microphone. The word cardioid means heart and it picks up sound in a heart pattern around the microphone. This make the microphone fairly direction and also fairly good at rejecting any reflective sound from more than say 10 feet away often experience in interiors. The cardioid, the hyper-cardioid and super-cardiod microphones are actually the microphone that most often lives at the end of the boom pole on most television and movie sets. One of the most popular in this class of microphones is the Schoeps CMC61.
So what’s the take away? As always, use the right tool is the right tool for the job.