> Any source for determining the duration of the flash burst from the
> 550EX at various power settings? Nikon publishes this in the manual
> for the SB28 but the Canon manual does not. I have a need to know
> in my application of photographing hummingbirds with two 550ex's set
> on low power very close to the birds. The flashes will be set at
> 1/64 and 1/128 output on full manual. The flash meter will get me
> the correct exposure but I require a very short duration to stop the
> wings, preferably shorter than the 1/8700 sec of the SB28's on
> 1/64th power.
You are correct, Canon does not publish flash duration data on current
speedlites. Canon did publish the _Speedlite Reference Guide_ in 1991
and in it stated:
"Though the intensity and duration of the flash burst vary
according to the size of the tube and the control circuitry
of the flash unit, typical durations range from 1/750 to
1/20,000 second."
The SRG was published before the 540EZ or 550EX. ...so what does that
tell us? Not much.
Unless you are willing to purchase more powerful lights, why not just use
what you have? I know from first-hand experience that the 550EX's (using
E-TTL) are capable of freezing the wing motion, except where the wings
are at maximum velocity (and usually out of focus anyway). Good luck.
Dave Herzstein
[EMAIL PROTECTED]
http://www.kjsl.com/~dave
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