---------- Original Message ----------------------------------
From: Jim Brokaw <jbrokaw@xxxxxxxxxxx>
Reply-To: olympus@xxxxxxxxxxxxxxx
Date: Tue, 27 Nov 2001 21:52:08 -0800
>on 11/27/01 12:19 PM, Walt Wayman at hiwayman@xxxxxxxxx wrote:
>
>
>snipped Walt's highly scientific description
>
>>The results:
>>
>> OM-1: 59 dB
>> OM-4: 59 dB
>> OM-4Ti: 58 dB
>> OM-1 with mirror locked up: 57 dB
>> OM-4 with mirror and aperture prefire: 57 dB
>> OM-4Ti with mirror and aperture prefire: 57 dB
>> Self-timer beep: 20 beeps @ 56 dB, last 4 @ 60 dB
>> Any OM with Winder 2: 67 dB
>> Any OM with Motor Drive 2: 62 dB
>>
>
>Walt, I think 3db represents a *doubling* of the sound level. So
>1db would be a noticable and significant difference... but how
>repeatable are your measurements? Did you try each one many
>times, or just once/a few times?
>
>I think your results would be more statistically valid if you
>tested more OM bodies in each configuration... which means you
>need to buy more OM's -- all in the interest of science, of
>course!
>
>;-)
>--
>
>Jim Brokaw
>OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
>
I repeated each measurement 10 times, and in every case only one
or two readings showed a 1 dB difference, so I just accepted the 8
or 9 readings that were the same and threw out the odd one or two.
As far as decibels and what they really represent, I won't try to
explain something I'm not sure I fully understand. I lifted this
from the Howitworks web site:
The decibel (abbreviated dB) is the unit used to measure the
intensity of a sound. The decibel scale is a little odd because
the human ear is incredibly sensitive. Your ears can hear
everything from your fingertip brushing lightly over your skin to
a loud jet engine. In terms of power, the sound of the jet engine
is about 1,000,000,000,000 times more powerful than the smallest
audible sound. That's a big difference!
On the decibel scale, the smallest audible sound (near total
silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound
100 times more powerful than near total silence is 20 dB. A sound
1,000 times more powerful than near total silence is 30 dB. And so
on. Here are some common sounds and their decibel ratings:
Near total silence - 0 dB
A whisper - 15 dB
Normal conversation - 60 dB
Lawnmower - 90 dB
A car horn - 110 dB
A rock concert or a jet engine - 120 dB
Gunshot, firecracker - 140 dB
End of quoted stuff.
For those interested in more examples, try this link:
http://www.coolmath.com/decibels1.htm
And I?ll be happy to test other equipment. I?m especially curious
about the sound level of an OM-3Ti, and I think some long-term
examination of the effects on camera sounds of certain lenses,
particularly the 180/2, 250/2 and the 350/2.8, etc., would benefit
mankind in many ways. Those of you who have any of these may
contact me off list for details on where to send them. This
project could take a long time, but consider it your contribution
to the furtherance of human knowledge.
Walt Wayman
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