How Harold Edgerton's "Bullet through Apple" stopped time

Written by Oscar Holland, CNN

In Breakwe examine the power of a single photograph, telling stories of how modern and historic images were created.

Exploding with energy but perfectly still, Harold “Doc” Edgerton’s 1964 image of a .30 caliber bullet ripping through an apple showed an otherwise unseen moment in captivating detail. The scene took on a serene, statuesque beauty as the disintegrating apple skin opened against a deep blue backdrop.

The image is widely believed to be a work of art. But more importantly for its creator, it was also a feat of electrical engineering. The longtime Massachusetts Institute of Technology (MIT) professor used it to illustrate a lecture, titled “How to Make Applesauce”, in which he explained the pioneering flash technology that helped him take the Photo.

Edgerton, who died in 1990 at the age of 86, is considered the father of high-speed photography. The camera’s shutter speeds were too slow to capture a bullet flying at 2,800 feet per second, but its strobe flashes – a precursor to modern strobe lights – created bursts of light so short that a photograph taken well-timed, taken in an otherwise dark room, felt like time had stood still. The results were fascinating and often messy.

“We used to joke that it took a third of a microsecond (a millionth of a second) to take the picture – and all morning to clean up,” recalls his former student and teaching assistant, J. Kim Vandiver, in a video. call from Massachusetts.

The 1964 image has become one of the best-known photographs of the 20th century. Credit: Harold Edgerton/MIT; Courtesy of Palm Press

While early cameramen experimented with pyrotechnic “flash powders” that combined metallic fuels and oxidizing agents to produce a short, bright chemical reaction, Nebraska-born Edgerton created a much shorter, more controllable flash. His breakthrough was more in physics than chemistry: After arriving at MIT in the 1920s, he developed a flash tube filled with xenon gas which, when subjected to high voltage, blew electricity between two electrodes for a fraction of a second. .

By the time he released the shutter for his now famous apple shot, Edgerton had developed a microflash that second-hand ordinary air rather than xenon. He had also produced decades of well-known picturesflying hummingbirds, golf clubs hitting balls and even nuclear bomb explosions. (During World War II, Edgerton developed a special “rapatronic” – or fast electronic – camera for the Atomic Energy Commission that could control the amount of light entering the camera during explosions.)

Still, it was his 1960s bullet photos that proved to be some of the most memorable. According to Vandiver, who still works at MIT as a professor of mechanical engineering, the challenge was not producing a flash but triggering the camera at the right time. Human reactions were too slow to take the shot manually, so Edgerton used the sound of the bullet itself as the trigger.

“There would be a microphone out of the picture, just down there,” Vandiver said. “So when the shock wave from the bullet hit the microphone, the microphone triggered the flash, and then you would close the (shutter afterwards).”

Making an icon

Over the years, Edgerton and his students have taken a gun to objects such as bananas, balloons and playing cards. For Vandiver, the reason why the apple – with a picture from 1957 of a splashing droplet of milk – became one of Edgerton’s defining photographs is, in part, its simplicity. “It captures your imagination…and you immediately understand what it is,” he said.

Another of Edgerton’s famous photos, taken in 1957, shows the crown-shaped splash produced by milk droplets. Credit: Harold Edgerton/MIT; Courtesy of Palm Press

There was another factor at play: Edgerton’s artistic eye. The compositional beauty of his images has seen them republished in newspapers and magazines around the world, and more than 100 of his photos are now held by the Smithsonian American Art Museum. Still, Edgerton rejected the additional title.

“Don’t make me look like an artist,” he said. “I’m an engineer. I’m after the facts, only the facts.”

While Vandiver said “there is definitely an artistic legacy” in Edgerton’s visual experiments, which advanced the field of photography, his research also had a huge impact on science and industry. His hands-on approach lives on at MIT Edgerton Centerwhich was established in his honor in 1992. Vandiver, who is the center’s director, said each student is encouraged to take their own ball shot.

“We’re still teaching the course, and the students are still thinking of weird things to take pictures of,” he said, recalling recent images of colored chalk and bullet-torn lipstick. “Apples are boring now.”