Franck was well known for her documentary-style photographs of important cultural figures such as the painter Marc Chagall, philosopher Michel Foucault and poet Seamus Heaney, and of remote or marginalized communities such as Tibetan Buddhist monks, elderly French people, and isolated Gaelic speakers. Michael Pritchard, the Director-General of the Royal Photographic Society, observed: "Martine was able to work with her subjects and bring out their emotions and record their expressions on film, helping the viewer understand what she had seen in person. Her images were always empathetic with her subject." In 1976, Frank took one of her most iconic photos of bathers beside a pool in Le Brusc, Provence. By her account, she saw them from a distance and rushed to photograph the moment, all the while changing the roll of film in her camera. She quickly closed the lens just at the right moment, when happened to be most intense.