He remained a busy cinematographer in the second half of the 20s.
He was able to continue his film career during World War II and he shot "Trenck, der Pandur" (1940), "Carl Peters" (41), "Geheimakte W.B. 1" (1942), "Sieben Jahre Glück" (1942) and "Orient-Express" (1944).
Franz Koch became established as a cinematographer from 1920 and he shot numerous silent movies like "Der Verfluchte" (1921), "Der Schrecken des Meeres" (1924) and "Der Schuss im Pavillon" (1925).
Besides his activity as a cinematographer he also appeared twice in front of the camera as an actor in "Die Drei um Christine" (1936) and "Jonny rettet Nebrador" (1953). Furthermore he wrote the screenplay and was the director of the short film "Lied der Landstrasse" (50).
Thank to his enormous experience Franz Koch became also a demanded cinematographer after World War II and he remained active in his job till his death.