How to Select Wireless Microphones for Video Cameras
Wireless, battery-powered microphones are the only way to go when you do not want the hassle of a wired microphone or when the microphone on the camera isn’t enough.
There are three parts to a wireless microphone setup: the microphone and the transmitter - worn on the subject - and the receiver, usually attached somewhere on the camera or camera operator.
In basic terms, the microphone attaches to the transmitter, and the transmitter sends the audio wirelessly from the microphone to the receiver. The receiver then plugs into the microphone input on a video camera, or into a mixer, etc.
News camera crews will usually use a microphone plugged into the camera. This makes it easier and quicker to get the story without setting up the wireless. However, if you are like me, in the corporate world, we do not have to hurry and can usually take our time in the set-up process.
The microphones most commonly used are called lavaliers. These are small and can easily be hidden on the subject, hooked onto a shirt collar or tie. The microphone connects to a wire, which takes it to the transmitter. The transmitter is a small pack that connects to a belt or belt loop, or can be put in a pocket. However, you should try to keep the antenna of the transmitter from becoming hidden under clothing, as it needs to transmit the signal to the receiver as efficiently as possible.
Receivers are small, as well, and have an antenna to receive the signal from the transmitter. They can be clipped directly to a camera, in my case, to the hot shoe of the Canon DS 60N that we used for videos.
The transmitters work only with one microphone, so if you have more than one wireless microphone, you would need a receiver capable of dual channels, a camera with two channels or a mixer to run multiple microphones into, which sends to output to your camera.
When selecting a wireless microphone, you should use one that works on the UHF frequency, or Ultra High-Frequency. The UHF frequency does not compete with police, firefighters, security firms, etc. who work on the VHF frequency. You will eliminate a police or fire call from interfering with your video shoot.
Also be aware that wireless microphone systems can be frequency-agile or fixed-frequency. Frequency-agile simply means that you can change the frequency that the transmitter and receiver operate on. You will want this if there is the possibility of interference from other wireless signals or if you just want the peace of mind that you can fix an interference problem. You can change and match the frequency settings on both the transmitter and receiver in order to find a clear channel. Fixed-Frequency means that you have only a single channel. You have to live with any interference with this system, as you have no other channels to use.
Receivers come in two choices: Diversity and Non-Diversity.
Diversity means that a receiver has the ability to prevent drop-outs and interference.
Non-Diversity receivers do not fix these problems.
You Get What You Pay For
Wireless microphone systems come in a wide array of prices. Do not expect much from a cheap, $100 system. We have a few here that do not work well. They drop out and pick up interference easily. Reliable brands are Audio-Technica, Samson, Shure, Nady, and Sennheiser. Expect to pay $300+ for a reliable system. You should be able to find a wireless system that meets your needs by reading reviews of retail web sites and doing research on the internet. I am doing this to replace our current system and finding that there are many fine choices to choose from.
EDIT April 7, 2012: The Canon camera in the picture above failed to work well for me. These cameras only record a short amount of video. The camera would stop recording at times, or would not even start to record. This problem is well-discussed on forums, and there does not seem to be a good answer. I took this camera back and got a Canon XF100 HD video camera, which works well.