Toomas's Photo Website Flash Discharge Graphs

Discharge Graphs of an Electronic Flash
 
Part of Toomas Tamm's photo pages

In February 1997, Jeremy Stein, an amateur photographer and physicist working in Albuquerque, New Mexico, measured the light output of Canon 430EZ and 380EX electronic flash units. The results are described in the following pages.

For the impatient, here is the most important result:

This is the discharge curve of the 380EX flash unit at full power. The rapid rise and a slower decay of the light output are well visible. The horizontal axis is time, and the whole graph represents a duration of 5 milliseconds (1/200 of a second).

Now the full story, mostly as written by Jeremy himself:

• The experimental setup used for the tests;
• Canon 430EX flash at differemt power levels;
• Canon 380EX flash in high-speed sync mode;
• Dependence of the output of the flash on the charge time;

Last modified: 07 July 1999