Son of a photographer, Hák started to work independently in 1925, in Prague and Bratislava. In 1937 he began collaborating with the D34 Theatre of Prague as a photographer, and a few years later he worked in the film industry. From 1942 he joined Group 42 of Czech avant-garde artists. He continued to work as a photographer at the Institute of Art Theory and History of the Czechoslovak Academy of Sciences from 1954 until the end of his career.