I have read a ream of articles on microphones. Many, if not most, end up sounding like promotional brochures. More about reviewing and recommending brands, that instructing the reader. I have used a myriad of microphones over the years. I’ve also sold them for two retailers. For those shooting video, using an external mic is probably the biggest improvement you can make. Virtually all camcorders and DSLRs, have poor quality microphones. Worse yet, most are built into the body of the unit, picking up both handling noises, and mechanical noises the device makes. There are a wide array of microphone designs available today. For the purposes of recording audio for video, we can narrow it down to about three general types of microphones. Your camera must of course offer the correct connection for the microphone you choose. If it does not, there are devices to address this, but we won’t get into that here.
Hand Held Microphones

On most any interview on TV, you will see a reporter holding a microphone up to the interview subject. Hand held mics are ideal for this application. You can use the very same mic used by performers, but most TV news production units use something a little different. Performance microphones are usually somewhat directional, and are referred to as “cardiod” mics, due to their heart shaped pickup pattern. For video, an omni directional mic is usually a better choice. You can pick up both sides of the interview, without constantly moving the mic back and forth.
Lavaliere Microphones

Lavaliere mics, often referred to as “lapel” mics are very common in broadcasting. Virtually every talk show, and news program use these. “Lav” mics are available in both wired and wireless versions. The latter has obvious advantages. If you’re on a budget, go with a good wired lav. Don’t be swayed by cheap wireless rigs. They are just not worth it. A good wireless setup will easily cost you several hundred dollars, or more. Another alternative is to simply rent a wireless system. Most larger cities have rental houses that will provide these at a low rental fee.
Shotgun Mics

A shotgun mic is designed to pick up sound in a very narrow pattern. They reject sound from the sides, allowing a bit more “focus” on the sound in front of the mic. In filmaking, these are used extensively. Most often mounted on the end of a boom pole. The boom may be held by an operator, or on a tripod mounted boom. There are a number of shotgun mics designed for mounting directly on a video camera. This style is often used by news camera operators. The biggest mistake most newcomers make, and it is a big one, is thinking that buying a good shotgun is the complete solution for all sound capture. It is not. The common misconception is that they work just like a camera telephoto lens, allowing the same result from far away, as if you were up close with a conventional mic. They do not.
The Bottom Line
The simple fact is, that an expensive microphone at a distance, will not come close to matching a cheap one placed close to the subject. Yes, that $2000 shotgun you’ve seen online, placed across the room, will not hold a candle to a $39 mic placed close to the source. The web is brimming with video that suffers from this common mistake. Anything more than about six feet away or more, and no matter how fancy the shotgun, it will never match a cheap vocal or lav up close. Again, our “cheap” mics in this example are wired. Always avoid cheap wireless stuff.