Paul C. Buff, Inc. Technical Forum

As for the model lamp going off when the flash is fired, this will do nothing to eliminate the modeling lamp from the exposure, since the decay time when an incandescent lamp is turned off is in the range of 100 times the flash duration. So the flash has come and gone by the time the modeling lamp is extinguished.

Also, the flash is about 2.5 times more efficient than the modeling lamp, so Support's statement At 1/250 of a second shutter/sync speed, you would capture 1/250 of a second's worth of a 250 watt bulb, a.k.a. 1Ws would actually result on an effective modeling lumenseconds of 4/10WS compared to the 2.5WS flashpower.

In the real world, the amount of light contributed by the modeling lamp is so small compared to the flash as to have no effect.

Of course, if you are shooting with very long exposure times, say 1 second, the modeling lamp will contribute to the exposure.

Thanks! I figured, was capturing some splashes and the modeling lamp on or off didn't make any difference. And need to say, fantastic support. Thanks!