He helped develop the "street photography" or "real life reportage" style that has influenced generations of photographers that followed.
The anonymity that the small camera gave him in a crowd or during an intimate moment was essential in overcoming the formal and unnatural behavior of those who were aware of being photographed. He enhanced his anonymity by painting all shiny parts of the Leica with black paint. The Leica opened up new possibilities in photography — the ability to capture the world in its actual state of movement and transformation. He said, "I prowled the streets all day, feeling very strung-up and ready to pounce, ready to 'trap' life." Restless, he photographed in Berlin, Brussels, Warsaw, Prague, Budapest and Madrid. His photographs were first exhibited at the Julien Levy Gallery in New York in 1932, and subsequently at the Ateneo Club in Madrid. In 1934 in Mexico, he shared an exhibition with Manuel Alvarez Bravo. In the beginning, he did not photograph much in his native France. It would be years before he photographed there extensively.