Cheap Microphones - An Explanation.
One of the most common questions in this part of VideoForums is "What (cheap) microphone should I buy for video recording?" The answer, given time and time again is "None." The trouble is, some newbies don't want to hear this and keep asking the question in the hope that, miraculously, they will get a different answer. So, I'm going to try and explain why there's no such thing as a "decent" cheapo microphone.
It doesn't matter which camcorder you buy, the in-built microphone will not be the best solution to recording sound. It's better than nothing, but only just. Even on a £4k camcorder, the manufacturer will only have spent £25 on the microphones. They figure that most serious videographers will buy a separate microphone anyway. So, theoretically, a £50 - £100 mic should sound better than the camera's mic. Unfortunately it doesn't work like this.
Cheap microphones sound like cheap microphones. They are often identical to the capsules used in the camcorder mic, just in a different housing. When you consider that the housing, packaging, transport and import duties will be about 70% of the cost of a sub-£100 mic, you can see how little is left over for the actual capsule and electronics! There is a myth that cheap chinese microphones are identical to more expensive makes, since some of the expensive brands' components are made in China. This isn't the case. What sometimes happens is that components rejected by known brands find their way into the cheap mics. Not an ideal situation by any stretch of the imagination.
In the same way cheapo mics from firms like Vivanco, Hama etc will not improve your sound dramatically. When you work out labour costs (small though they are in some countries) A £50 mic will still only have components worth about a fiver!
One fact should be remembered at all times: To get the best sound, you need to get in close. Distance kills sound. It reduces the clarity and the high tones. A cheap microphone up close will, nearly always, sound better than a good microphone a long way away. Since it's not always practical to have the microphone six inches in front of the speaker's mouth, different types of microphones have been developed. The most common, for video use, is the "shotgun".
The following is meant to let beginners have an idea of how microphones work. Some explanations have been simplified or reduced in order to avoid ten pages of technical descriptions.