One of the principles of good audio recording is to bring the microphone close to the source. That’s why audio usually sounds bad when recorded from a smart phone or an on-board camera mic. The mic is simply too far away to record good audio. A lavaliere mic attached to the person about ten inches below the mouth will sound 100 times better than the camera mounted mic. If you must use the on-board mic, get as close to the person speaking as you can.
Microphones with XLR connectors record better audio with little or no interference. Mics with min plug jacks often have interference problems. The reason is the cable on a mini plug mic is unshielded and acts like an antenna, picking up radio signals and other unwanted electrical noises. So if your camera does not have XLR inputs (which we highly recommend), use an XLR adapter like the BeachTek DXA-5Da Passive Dual XLR Audio Adapter.
Choose The Right Mic For The Job
These mics are versatile and can be used in a wide variety of recording situations, with the exception of very loud environments. Shotgun mics often ride on the video camera, and can be removed and used by another person who often can get closer to the audio source.
These mics are great for mobility. The subject can walk around without pulling your camera over. Wireless systems are available to mount on your camera. There are wireless lavalieres and wireless handheld mics. Good wireless mic systems can be pricey. This is why many have given up their wireless mics for audio recorders. See Wireless Mics Are Dead.
These are the standard for on-the-go interviews. See the Shure PG48-XLR Cardioid Handheld Mic with XLR connector.
Boundary/PZM Microphones These inconspicuous mics can be placed on a wall, table, podium wherever you want wide coverage. They are designed to lie flat and be inconspicuous. They respond best when surface-mounted. They do not work well when hand held or stand mounted.
For the most direct pickup of an individual person, a lavalier is often times the best way to go. If you were only going to buy one or two mics, wired lavaliere mics would be a good choice. They are the standard for interviews.
More than the Microphone
Location scouting before the shoot can help reveal audio problems like street sounds, trains, planes or factory sounds that could ruin the audio. Some other hidden culprits waiting to cause audio problems are soda machines, air conditioners, and ventilation systems. They will come on just when you want total quiet. You might even bring the camera to a location. Turn the gain up and listen carefully with headphones to the sounds of the place.
Always use windscreens on microphones that are used outdoors. The sound of any wind across an open microphone is much worse than you would think. The human ear does not hear these wind noises the way mics hear. It’s often impossible to remove wind noise after the fact so you must fix it before you record audio.
A Separate Audio Recorder
The film industry has been using this technique of having a separate audio recorder forever. It is called double system recording and it has much to recommend it, especially today with the new inexpensive, but high quality audio recorders. The only catch is synching up the audio track in post production, but that is easily solved with a great program called Plural Eyes. In complex situations you can use several recorders to get the audio from different people or settings. The American Director, Robert Altman, was famous for this technique in films like Nashville.
Fix it in Post (sometimes)
It is worth your while to become familiar with audio EQ and mixing concepts. Many of the best video editing programs have built in audio editors with EQ and other filters. Learning the capabilities of this software is a good investment of your time.
“Sound is half the picture.” —George Lucas