Stop It!

What if you could stop a falling drop or freeze a running child in his steps? What would you see?

That's what Harold "Doc" Edgerton wondered, so he invented a way to stop motion with his camera. By lighting a moving object for a fraction of a second with a specially designed flashing light called a stroboscope and then taking a picture, Doc was able to capture individual moments of movement on film. In doing so, he revealed an amazing and often beautiful world.

In the 1930s, in a darkened lab he called "Strobe Alley" at the Massachusetts Institute of Technology in Boston, Doc began taking pictures of anything that moved: water dripping, birds flying, balls bouncing. He created a way for his camera and strobe to work together so that when the strobe flashed, the camera took a picture. To time the picture accurately, Doc devised different ways to trigger the strobe, sometimes by sound and sometimes by the movement of the subject. To record a sequence of movements, such as the running boy above, Doc set his strobe to flash as fast as 300 times a second. At each flash, the camera took a picture.

To get the same effect, try this: Gaze at a turning wheel or fan and rapidly blink your eyes. See how each blink stops the action? If your eyes were strobe lights hooked to a camera, each time you opened them, a picture would be taken.

Doc's "motion pictures" show us many things human vision can't see. They help scientists study the way birds fly and the way people move. They picture what happens when one object strikes another, and how fast bullets and balls speed through the air. Strobe technology can even be used to examine fast-moving machinery, such as the moving parts of a car's engine. And Doc's inventions led the way to modern flash cameras.

The Shape of Air

Doc used mirrors and special filters along with his strobe light to take "shadow pictures" of the air. The heat from this match made wavy changes in the density of the air, which could then be captured on film.

Diving in the Dark

It took only one and a half seconds for this diver to splash into the water, but Doc's camera caught each graceful movement. He set the strobe so that the camera took about 30 pictures during the dive. Because the diver moved more slowly as he left the board, the pictures piled up on one another. As he fell faster, he covered more distance between flashes. For the strobe to be most effective, the room had to be completely dark.

Copyright Carus Publishing Company May/Jun 2004
Provided by ProQuest Information and Learning Company. All rights Reserved