Freund was an innovator in the field of cinematography, often noted for pioneering the unchained camera technique, arguably the most important stylistic innovation of the 20th century, setting the stage for some of the most commonly used cinematic techniques of modern contemporary cinema.

His career began in 1905 when, at age 15, he was hired as an apprentice projectionist for Alfred Duskes films.

Freund was drafted by the Imperial Army to fight in World War I but was released from duty after only three months.

Freund's only known film as an actor is Carl Theodor Dreyer's Michael (1924) in which he appears as a sycophantic art dealer who saves the tobacco ashes dropped by a famous painter.

[4] Freund immigrated to the United States in 1929, where he continued to shoot well-remembered films such as Dracula (1931) and Key Largo (1948).

In 1944 he founded the Photo Research Corporation of Burbank to manufacture TV cameras and exposure meters.

In an interview Richard Brooks tells a story of his interactions with Freund when they worked on the film Key Largo together.

"[7] At the beginning of the 1950s, he was persuaded by Desi Arnaz at Desilu to be the cinematographer for the television series I Love Lucy from 1951.

While Freund did not invent the three-camera shooting system, he did perfect it for use with film cameras in front of a live audience.

[10] In 1941, he founded Photo Research Corporation with the intent to develop products to improve the quality of motion picture photography.

That meter accompanied 1950s astronauts on the Project ManHigh balloon missions reaching nearly 100,000 ft altitude.

Freund borrowed some of the technology that had been developed by William Baum of the Palomar Observatory to measure star luminance.

Freund married Susette Liepmannssohn in 1915; they had one daughter and later divorced, though sources differ on whether their marriage ended in 1918[10] or 1920.

[10] In 1937, he visited Germany to bring his daughter to the United States, saving her from almost certain death in the concentration camps.

His ex-wife, Susette Freund, remained in Germany, where she was first imprisoned in Ravensbruek Concentration Camp and then eventually murdered at the Bernburg Euthanasia Center in March, 1942.