Audio For Video
The sound quality of DV camcorders is excellent and in lots of instances the built in microphone does a good job. At some point though, it will be inevitable that an external microphone will be needed, for the simple reason that for a good audio recording the microphone needs to be in a different position to the camera.
Before dashing out and spending large amounts of money it is best to consider a few points. Does the sound need to be synchronised with the picture? It might be possible to record the sound separately (and in a more favourable location) to the images. If the answer to this is no then can the built in camera microphone be detached from the camera and moved closer to the subject using an extension cable? If the microphone is detachable, then experiment with set ups that are similar to that which you will be filming. This does not cost anything other than time and will give a good idea of the results possible.
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general purpose microphone that is designed to attach to a camcorder |
Audio Technica microphone which can either be used attached to the camcorder or with an extension cable |
A boundary microphone ideal for use on tables |
If a separate external microphone is needed the main requirement is that it
should be compatible wit
h
the camcorder. Most consumer camcorder microphone inputs use a 3.5mm jack plug.
This uses what is known as a two terminal unbalanced connection. Professional
equipment uses three terminal XLR balanced connectors. Whilst the actual
connectors are incompatible it is possible to swap either type of microphone and
input with a suitable adaptor. The main thing is be aware that different
connectors exist and if you are unsure take the camcorder with you when you buy
the microphone. The main advantage of balanced connectors is that they are less
susceptible to picking up interference. Consumer camcorders are unlikely to have
balanced XLR connectors ands even at the prosumer level the only one that I am
aware of with XLRs is the Sony PD150. See the picture on the right. Ironically
the original PD150 had problems with the sound and the Cannon XL1 with 3.5mm
jack inputs was considered superior.
Microphones come in two basic types, dynamic and condenser. The dynamic microphone generates a signal by moving a wire coil past a magnet and the condenser microphone generates a signal varying the gap between two charged plates. The only thing to know about the difference between dynamic and condenser microphones is that the condenser microphone needs a power supply. With professional systems this can be provided by the camera. With consumer camcorders an electret condenser microphone powered by a small internal battery would be needed and as a good general purpose microphone this type would be the best to get.
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Tie clip mics can be bought in a range of prices |
A more expensive camcorder mic |
With radio mics you need a battery operated receiver that can be strapped to the camcorder |
Although I have stated that microphones can be categorised in to two general types there are many different shapes and sizes. Lots of these are designed for specialised use. For video work the only alternatives to a general purpose directional microphone would be a tie clip microphone and a boundary microphone that would be used on a table top to pick up anyone sat around it. All of the above microphones could be coupled to a radio to provide even greater flexibility at an additional cost. If you don't want to buy many specialised microphones just go for a general purpose type (see pictures)
For more specialised work and picking up more than one microphone or audio source a small mixer is required. Those designed for video location work tend to be aimed at the professional user and are expensive. Cheaper mixers can provide more than acceptable results but because they are not designed for location work they are more cumbersome to use. By the time external mixers are required you should have a good idea of what you will need or a specialist sound man who does.
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Low cost mixer |
A proper ENG (electronic news gathering) mixer will probably cost as much as a small camcorder |
Another example of a professional mixer |
