Paul C. Buff, Inc. Technical Forum

i always thought that the higher the flash power the longer the flash duration but i just read in the manual it seems to say the opposite btw i have b800s and b1600s

With speedlites, Einstein, or other IGBT controlled lights, the lower the power, the shorter the flash duration.

Some older mono lights and some pack and head systems use capacitor switching to lower flash output by removing some of the capacity for stored energy. This will result in lower flash durations, but also less finite control over output.

Alien Bees, and White Lightning, as well as most other monolights, use voltage regulation to determine power. When voltage regulation is used, flash durations get longer as power decreases.

Some lights, like the WLX1600 and WLX3200, and our Zeus packs can utilize capacitor switching and voltage control for power reduction.

Capacitor switching and properly implemented IGBT (Einstein) will also maintain color consistency from one power level to the next.

Voltage control (and to some degree, other-than-properly-implemented IGBT) will alter color as power is adjusted. Voltage controlled lights will shift down +/- 80K per stop. This applies to our lights, as well as the "high end" european lights, despite thier claims. IGBT will shift up as power is decreased, unless steps are taken to prevent this.

Lots of info about all of this here: http://www.paulcbuff.com/sfe.php

so with my b800s and b1600s is the flash duration shorter at lower power or longer? and what does IGBT stand for? thanx

The flash duration is longer at lower power with the B800 and B1600. Said another way, the shortest flash duration is at full power for B800 and B1600 lights. These lights use voltage regulation to control output.

The opposite is true for Einstein - the flash duration gets shorter by reducing power. Einstein's shortest duration is at its lowest output. Einstein has IGBT control.

IGBT = Insulated Gate Bipolar Transistor. Basically it is a fast electronic switch with a sharp cut-off.