AlienBees
Below is AlienBees’ response regarding my observation on their strobes in low-power mode.
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Dexter,
The AlienBees lights, as well as most other continuously variable output flash units including White Lightnings, affect power reduction by reducing the voltage impressed upon the flash capacitor bank. It is a characteristic of a xenon flash tube that the color temperature of the emitted light will fall as the voltage applied to it is reduced. Paul Buff included a circuit in his designs that helps to lessen this effect, but it is not possible to eliminate it. The AlienBees and White Lightning products will produce output color temperatures of between 5500 and 5600 Kelvins at full power. The color temperature will drop about 250 to 300 K as the power is reduced to minimum. The color temperature output for a unit in proper working condition should be reasonably consistent for any given power setting. At near-minimum power settings, the accuracy of the output power as well as the color temperature consistency can be adversely by the light output of the modeling lamp: it’s a good idea either to defeat the MODEL READY function, or to turn the modeling lamp OFF after setting up the shot: incandescent lamps simply CAN’T turn off instantaneously, or even with repeatable characteristics.
I noticed that the forum thread did include the appropriate warnings about measuring color temperature: the surroundings and the reflector characteristics have as much to do with the measurement as does the light itself. In addition, off-axis measurements, even using the native xenon lamp, are more likely to be more characteristic of any nearby object than of the lamp itself. I think the bottom line, here, is this: how do your shots look?
Best regards,
Doc (for Joe Diebler)
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