Following up on my reply to Andy, and looking at the messages since.
Checked Langford, "Advanced Photography", 3rd Ed, 1974. Typical flash
duration 1/300 to 1/1500 sec, comparable to the Wikipedia figure.
A turntable at (approximation, save getting calculator out), 30 rev/minute,
2 sec per rev. 12" record has a diameter of around 36". therefore moves 18"
per sec. A flash of 1/100 sec would allow a movement of about 0.2", so this
rotation speed would be too slow for a faster flash.
In the past I have built phototransistor devices to use with an oscilloscope
to measure flash duration and also check shutter speeds. But ceased to have
access to these facilities 15 years ago when I retired (as a physicist). A
local school with a science lab may be able to help here.
Of course you must remember there is another major complication.
If the flash is used in manual mode with full power output the time will be
longer than in Automatic mode, where the flash output is quenched when the
desired illumination is achieved, hence it has a shorter duration.
Also some flash units allow use of 1/2, 1/4 etc power levels, using these
will also result in a briefer flash duration.
Jim Thyer
----- Original Message -----
From: "David Dyer-Bennet" <dd-b@xxxxxxxx>
To: "List for Photo/Imaging Educators - Professionals - Students"
<photoforum@xxxxxxxxxxxxxxxxxx>
Sent: Saturday, January 29, 2011 3:48 AM
Subject: RE: flash duration
At this point, however, it might be easier to find somebody with an
oscilloscope instead, hook up a photocell and power source to it, and just
expose the photocell to the flash.
--
David Dyer-Bennet, dd-b@xxxxxxxx; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
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Dragaera: http://dragaera.info
