[MacDV] Recommendations for Camcorder Mic

[Danny Grizzle]

On 12/3/02 4:33 PM, "Phil A. Lefebvre" <p-lefebvre at northwestern.edu> wrote:

> My wife asked for a gift idea, and I've been thinking about getting a
> better microphone for my Sony TRV-103 Digital 8 camcorder, mainly to
> better pick up voice sounds of stuff (amateur home video) I'm
> capturing from across a room. My first thought is the Sony ECM-HS1
> Gun Zoom microphone, since it claims to sync with the zoom. It is
> available at B&H for $55.
> <http://www.bhphotovideo.com/bh2.sph/FrameWork.class?FNC=ProductActivator__Apr
> oductlist_html___116496___SOECMHS1___REG___CatID=2513___SID=F21DA9D45F0>
> 
> Anyone have any experience with this device, and/or recommendations
> for something else?

"Gun Zoom microphone" is marketing verbiage, pure puffery. There is no such
thing as a zoom microphone. The long tube on a shotgun type mic is called an
interference tube. It works like this: holes of precision size and position
are placed along the mic barrel. By forcing sound waves to enter through
multiple "doors" along paths of different lengths, sound coming from
off-axis directions enter along multiple routes so that push meets pull in
air molecule vibration, thus canceling unwanted sounds. Not too different
than summing -1 and +1.

Problem is, cancellation is not perfect and the effect is better described
as attenuation. Effect varies with frequency, because variable
length/frequency of audio waves interacts with fixed dimensions of the
microphone interference tube.

Wherever you point a shotgun mic, sounds are much less affected, less
attenuation. But bottom line remains the same: at the end of the
interference tube sits the exact same mic diaphram as any other mic, and the
sound reaching it is no louder or better recorded simply because the mic is
big, impressive, and expensive.

The *only* effects of a shotgun mic on audio are: 1) worse fidelity because
of introduced frequency interference, and 2) some rejection of off-axis
sounds, usually outside camera view. The effect is not all that dramatic. It
will not make a busy street disappear from your audio track, and it will not
eliminate off-camera conversations. Sound continues to reverberate & reflect
in all environments, and bad stuff will intrude.

The *only* solution for quality audio is to get the microphone close to the
desired sound source and away from bad sound sources. This is why singers
press their lips to the microphone. Close mic'ing is not a persistent
fashion, it is a law of physics.

Shotgun mics can be useful, but the zone of benefit is measured in inches,
not feet or miles. Certainly the benefit in camera mounted applications is
marginal, at best, with a terrific compromise in portability and ease of use
for most amateurs. The real solution to better audio is better camera work:
avoid telephoto lens settings, and move the camera up closer to the subject
and source of sound.

For most amateurs, a shotgun mic is just a big chunk of junk atop a camera
that is smaller than the mic. It is a hassle to use, prone to snap off, and
difficult to pack in a case. In other words, a joke. The one mitigating
factor in my otherwise scathing opinion about this matter is the fact that
some super-simple consumer camcorders have internal mics which are so flawed
that *any* external mic would be an improvement. You be the judge; I am not
familiar with your equipment or how you use it. Even if you upgrade the mic,
the advice about close camera and mic position holds, completely valid.

Danny Grizzle