watts = energy per second
probably the rating for a strobe is watts x seconds = total energy
obviously if the time is longer the rate of power flow (intensity) is
less for the same total energy. If the type of bulb is similar and the
color of the spectrum is the same, probably about the same amount
of light would be emitted but if the reflectors were different the
useable light would be different.
-jeff (obviously I don't know anything about strobes)
----- Original Message -----
From: "John Hudson" <jahudson@xxxxxxx>
To: "LIST - Olympus" <olympus@xxxxxxxxxxxxxxx>
Sent: Tuesday, December 18, 2001 9:34 PM
Subject: [OM] rating of studio strobes
>
> I was told today that any two different brands of studio strobes each
> rated at 400 watts / second [or any other rating for that matter] might
> not deliver the same intensity of light output. By way of analogy my
> source said that in and of itself any particular strobe rating was like
> saying that an automobile's engine had four, or five, or six cylinders
> and so many valves but did not imply or specify the actual power output
> other than suggest, for example, that a 800 w/s rating was likely to be
> twice as intense as a 400 w/s rating.
>
> Can any one out there explain just how you measure the intensity of
> light output by reference to the watt per second rating and how this can
> be converted into a guide number for any particular ISO film speed?
>
> John Hudson
>
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