Diane Arbus was American photography’s bravest detective. Born in 1923 and raised in leafy privilege (her father was the president of a department store on Fifth Avenue), the young Arbus spurned the path of bourgeois domesticity and propriety to patrol the outskirts and no-go areas of the demimonde, armed with only a 35-mm. Nikon and a fierce supply of inquisitive nerve. She haunted flea circuses, carnival sideshows, and strip clubs, made nighttime expeditions into Times Square and Coney Island (then at their most dangerous and squalid), and recorded life on the fly on New York City streets.

Like so many photographers in the heyday of Henri Cartier-Bresson, Arbus was in pursuit of the “decisive moment,” the chance epiphany. It was when she upgraded from the Nikon to the medium-format Rolleiflex, with its bulkier body, larger negative, and square frame, that she found her true eye, her visual voice. The roving voyeurism of 35-mm. street photography had prepared the stage for a formal portraiture where Arbus and her subjects faced each other full-on for posterity.