From: Klas Strandberg <>
>>>With the parabolic it is in focus or out. There is no smooth
>>>transition.
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> Yes, there is. The size of the focus varies with frequency.
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> Klas.
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>>>With a shotgun the center is more like the ear to find the sweet spot.
>>>
>>>You can read that a shotgun has no gain but the truth is a bit more
>>>gray. If you have a sensitive directional mic that is has a pattern
>>>more close to the ear in direction ability, then it is easy to find
>>>the sweet spot in the blind. It still can do a selective receive
>>>that a dish can do.
First off this grew out of the assumption that being blind means a
person cannot hear the direction of the sound. Nothing could be farther
from the truth. Friends I have that are blind can point exactly where
some sound is and describe it far better than a person with sight, they
don't need to see the bird. I see no problem in their using a parabolic,
in fact I've handed my parabolic to a blind person, and he had no
problem using mine. No instruction necessary he already had what he
wanted to point at nailed. And he could scan up new things too.
It's not just that the size of the focus varies with frequency, I
certainly agree with Klas on this. The focus is also variable depending
on target distance. The bottom line is that a parabolic is hardly a
straight line only as to it's pickup. While the angle of acceptance of a
parabolic is narrower than a shotgun, it's still very wide and does have
a transition zone that's easy to use as a guide for centering the
direction of the mic. It's easy to zero in by ear with good headphones.
I submit it's even easier if you use a stereo parabolic, like the
telinga stereo. In frog survey recordings I'll usually survey a site
entirely with my headphones on, zeroing in on each little calling group
by ear. Bird folks need to try this more, with frogs your chances of
seeing the calling frogs are very low, so you always do it by ear. Try
recording with your eyes closed, listen to the sound.
The problem with shotgun mics in addition to having no extra gain that
won't increase the self noise as well, is that they tend toward the high
priced end, hard to cheaply hand make a quality shotgun mic, though I
have a few ideas. You will get more bang for the buck with a parabolic,
particularly at the less expensive end. Even once you get the shotgun
pointed at the bird, it's still hampered by less gain and a wider pickup
zone. Shotguns tend to have polar patterns that have a fairly even
pickup for the center 60 degrees or so, much harder to get exact aim by
ear. If anything they have greater need of visual sighting.
Try both a parabolic and a shotgun blindfolded, I think the parabolic
will win as far as aiming.
As far as the ear's angle of acceptance, it's more like the SASS than
either of these. It's our brain that then filters out all that came in
to make it appear like we were only listening in one limited direction
to a single caller.
Walt
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