What you and Moose are saying makes sense. I hadn't investigated how a
conventional shutter curtain works. Thanks for the info.
Anyway my plan was to use at least four slaved flashes set at 1/16th power.
This will generate a 1/10000s flash, and be bright enough for me to use f/16 or
f/22 on ISO 100 film. I will shade the scene from sunlight to reduce ghosting
during the 1/60s sync time.
As per Moose's suggestion I will test my setup as best I can before travelling
out to the hummers.
Matt
At 18:26 27-04-03 -0700, Jim Brokaw wrote:
>Matt -- When the OM-4 (etc.) does a 1/2000 exposure (0.5 milliseconds) the
>duration of the actual shutter curtains travel (the time for the curtains to
>travel across the film) is the same as for any other exposure. The slit
>width (the space between the first and second curtains) is such that any
>portion of the film gets only 1/2000 second of light, but the actual total
>length of exposure from the first bit of the image to the last bit of the
>image is ~1/60 second. The curtains take at ~15 milliseconds to cross the
>film plane opening, and the F280 flash is going off every 0.125 milliseconds
>during that time... so there are about 50 or 60 flashes during the time of
>the shutter curtains travel across the film plane.
>
>You might see some strobing effect on fast-moving subjects (like hummingbird
>wings) but with the multiple light bursts the effect is mostly as if there
>was one flash of a long enough duration to allow the whole curtain travel
>time to be illuminated. The F280 mimics the old "FP" flashbulbs, those had a
>long sustained burn time, during which the focal shutter plane curtains
>could cover the whole film area.
>--
>
>Jim Brokaw
>OM-'s of all sorts, and no OM-oney...
>
>
>> From: Matt BenDaniel <matt@xxxxxxxxxxxx>
>> Reply-To: olympus@xxxxxxxxxxxxxxx
>> Date: Sun, 27 Apr 2003 19:50:32 -0400
>> To: om@xxxxxxxxxxxxxxxx
>> Cc: olympus@xxxxxxxxxxxxxxx
>> Subject: Re: [OM] F280 FP
>>
>> Skip,
>>
>> I found an interesting article here:
>>
>> http://www.rit.edu/~andpph/text-streak.html
>>
>> Apparently in Super FP mode, the F280 pulses about 10000 Hertz. This implies
>> that the F280 would flash 5 times during a 0.5 millisecond exposure. That
>> does not sound equivalent to continuous lighting. For example, with moving
>> hummingbird wings, this could yield some interesting artifacts.
>>
>> It's also too bad that the engineers didn't make the F280 capable of
>> delivering a very bright duration of a few milliseconds that supports a
>> shutter speed of 1/2000s with a reasonably strong guide number.
>>
>> Matt
>
>
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Matt BenDaniel
matt@xxxxxxxxxxxx
http://starmatt.com
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