At the end of the war, he was hired by Edison and in 1951 he made a film on all the important hydroeletrical plants built in that period. In the following years, Olmi directed around 40 documentaries, including La diga del ghiacciaio, Pattuglia di Passo San Giacomo, Tre fili fino a Milano, Michelino 1aB (written by Goffredo Parise), Manon finestra 2 and Grigio (whose screenplay was written by Pier Paolo Pasolini).