Photograph of Atomic Bomb Testing, American West (via npr) Shannon Thomas Perich (associate curator of the Photographic History Collection at the Smithsonian): “The dangers of shockwaves and radiation required the camera to be placed 7 miles from the detonation site on a tower some 75 feet in the air. Exposure time was one-hundred-millionth of a second. The exposure time was so small that no conventional mechanical shutter could be used. A magnetic field was created around two polarized lenses that were rotated, permitting light to pass through an optical system.”

Photograph of Atomic Bomb Testing, American West (via npr)

Shannon Thomas Perich (associate curator of the Photographic History Collection at the Smithsonian): “The dangers of shockwaves and radiation required the camera to be placed 7 miles from the detonation site on a tower some 75 feet in the air. Exposure time was one-hundred-millionth of a second. The exposure time was so small that no conventional mechanical shutter could be used. A magnetic field was created around two polarized lenses that were rotated, permitting light to pass through an optical system.”