Piers,
Good idea.
Where are the sensors exactly on T32 and T20?
I don't have original manuals, and the diagrams in the eSIF are not too legible.
Matt
At 14:17 25-04-03 +0100, Piers Hemy wrote:
>To get the minimum flash duration out of an auto flash, Matt, seems to me
>you need simply to put a small reflector in front of the sensor to 'scoop'
>some of the flash out put straight back into the sensor.
>Thus what the sensor thinks is the flash-subject distance is a half inch or
>so, although the bulk of the output goes way past that.
>What the duration would be... I don't know for sure, though I am pretty sure
>it will be the minimum possible - but you have the flash metering capability
>to get the exposure right, at least.
>HTH!
>
>Piers
>
>
>-----Original Message-----
>From: owner-olympus@xxxxxxxxxxxxxxx [mailto:owner-olympus@xxxxxxxxxxxxxxx]
>On Behalf Of Matt BenDaniel
>Sent: Friday, April 25, 2003 12:49 PM
>To: olympus@xxxxxxxxxxxxxxx
>Subject: [OM] Fast Bright Flash
>
>
>I'm planning to shoot hummers later this month.
>
>One of the ways to stop wing motion is to use very bright fast flash. I'm
>NOT going to use TTL (cost and nonpredictability). I have four optically
>slaved Vivitar 283's with VP1's. Each 283 is powerful flash (GN 120 feet),
>but the trick is to use all of them in manual mode at a fraction of its
>power (1/8th or 1/16th), because that yields a very short flash (on the
>order of 1/8000th second or faster). Overall brightness is achieved by using
>multiple flash units (and the more the merrier) very close to the subject (2
>feet).
>
>The camera lens will be stopped down to about f/32 (for depth of field)
>using ISO 100 film, and I'll try to shade the subject from direct sunlight,
>in order to reduce ghosting. I'm shooting with an OM-4 synced at 1/60s.
>
>My question is whether I can supplement the 283's with slaved T20's or
>T32's. The problem is that if any of the flashes have a longer duration, the
>edges of the wings will be blurred. On the T32 in particular, there is a
>manual setting that uses 1/4 power. The question is: how long is that flash
>duration? I've looked in manuals, Olympus source books and the web but
>cannot find any such info. The nominal flash duration of the T32 is states
>as "1/50.000~1/1000 sec", but that says nothing about how to predict/control
>the duration.
>
>I know I can get an even shorter flash duration out of the T32 or T20 by
>using it in auto mode. By varying the distance of the flash to the subject,
>I can control how much light any single isolated unit would put out. But
>when there are multiple flashes being used, I'm less sure of how predictably
>the auto works. Ideally I'd like to see a graph for the T32 with millisecs
>on the horizontal axis, and power on the vertical axis. Any way to get that
>info?
>
>BTW I do have a basic flash meter.
>
>Any advice here?
>
>BTW here is some excellent background info on shooting hummers:
>http://www.rpphoto.com/howto/hummer/humguide1.htm
>--
>Matt BenDaniel
>matt@xxxxxxxxxxxx
>http://starmatt.com
>
>
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>
>
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--
Matt BenDaniel
matt@xxxxxxxxxxxx
http://starmatt.com
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