Electronic flash
1931 (Edgerton’s stroboscope)
A spark of electricity through a tube of xenon gives a flash lasting a few thousandths of a second or less, again and again. Harold Edgerton used it to freeze motion.
How it began
At the Massachusetts Institute of Technology, the engineer Harold Edgerton was studying electric motors in 1931. To see them at speed, he built a stroboscope: a lamp that flashed in step with the motor. He soon turned it on bullets, splashing milk and hummingbirds.
How it works
A capacitor stores electricity at high voltage. A trigger makes the gas in a xenon tube conduct, and the stored charge rushes through it in a brilliant, very short flash. The capacitor then recharges for the next one.
Why it mattered
Its flashes were short enough to freeze a bullet. Unlike flashbulbs, it could fire thousands of times. Studio photographers adopted it, and small units made it the standard flash from the 1960s.
Limits and what replaced it
Early units were heavy, with large batteries. Smaller electronics and automatic exposure control, and later through-the-lens flash metering, made it easy to use.
Today
Studio strobes, camera speedlights and the xenon flashes once found in phones all descend from it.