Henri Cartier-Bresson
Cartier-Bresson adopted the Leica early in his career and used it to develop what he called the "decisive moment" — the idea that a photograph's composition and meaning come together for an instant that either is or isn't captured. The Leica's quiet shutter and small, unobtrusive body suited his street photography, letting him work close to his subjects without drawing attention. He co-founded the Magnum Photos agency in 1947 and remained associated with Leica cameras throughout his working life.