Helen Levitt Captured Perfect Moments, Unnoticed : NPR

And she talked some about walking around the streets of New York and how she could capture those moments unnoticed.

“I had attached to my camera — I had a little device that fit on the Leica camera that they called a winkelsucher, which meant that you could look one way and take the picture the other,” she said. “You could turn your camera sideways.”

Check it out here.