Of course the reason for post-production is that sound recorded during the filming stage isn't nearly of a good enough quality to be used in the final mix, and so therefore needs to be re-recorded. And so it is important that the correct microphones are employed. Before I started research on the topic of sound design my knowledge of mics was thus; dynamic and condensers. The only other thing I knew was that some were cheap and some were around the same cost as a week's holiday in the Bahamas. My research on microphones involved a lot of e-mailing, and one of the replies I got was from John Rotundi in Los Angeles, and he had this to say.
"I currently hold the position of Chief Engineer at Enterprise Post-production in Burbank, California. Our facility is physically a bit smaller than that of a big feature lot, such as my previous employers at Skywalker Sound, 20th Century Fox, Todd AO, Warner Brother's, etc., might have , but all are equipped similarly. In our case, we have a dual purpose Foley/ADR stage, with covered Foley pits when we are doing dialog recording. When it comes to recording foley our gear stays the same, we usually use 2 mics; 1 near and 1 distance/ambient, these being the Sennheiser MHK-416 and/or the Neumann KMR-81". When I received and read John's e-mail I immediately went on the net to see these mics for myself, and was rather surprised by what I saw. The Sennheiser MHK-416 is a condenser mic with a super-cardioid polar response pattern that operates from a 12 volt phantom power supply, and is also known as a 'shotgun' mic because of its similarity in appearance to a gun. The advantages of this microphone and similar mics for post are its very low inherent self-noise, high sensitivity and balanced output as well as a tight pattern and excellent reach. The super cardioid response means that they are useful in multiple microphone situations where pickup of adjacent sound sources is a problem. The specs make it perfect for post-production sound recording.
Think of the shotgun microphone as a telephoto camera lens. A long lens will isolate and magnify a distant subject, but at the same time will compress the perceived distance between subject and background. Everything appears to be closer together than they physically are. The same sort of spatial honing takes place with microphones. The voice of the subject will sound closer, but any noise in the background will also be magnified. Therefore, the key to isolating the necessary source without background noise is to create a line of sight with the microphone that hears the voice but does not hear the background. This ability is the main reason why the 'shotgun mic is shaped like it is.
So to break it down a good quality condenser shotgun with an appropriate polar pattern and frequency response, positioned approximately two to three feet from the sound source is the general practice. With regards to location/field recording the models differ, mainly choices are based on portability and robustness, but the principles remain the same. Certain considerations must be made with field recording, and the biggest problem faced from recording outdoors is wind noise. But in the film industry there is a way of reducing the horrible 'rumble 'sound associated with blasts of gusty wind whilst trying to record a sound source outdoors, and it is by using what is known as a wind shield. |
