Born in Germany on February 15, 1877, Cronjager and his brother Jules moved to the United States.

In 1893 he became a photographer, initially working in portrait studios, before ending up in the art department of the New York Edison Co. Cronjager eventually moved into cinematography, working for companies such as Edison Studios, the Biograph Company, and Fox Film Corporation, being the first cameraman engaged by both of those studios.

His grandson, William Cronjager (through Henry Jr.), was an Emmy Award-winning cinematographer.

[3] His more notable silent films include 1917's Crime and Punishment, the Mary Pickford 1919 picture, Daddy Long Legs, and the 1921 film, Tol'able David.

[5] In an ironic twist, when he was demoted from cinematographer to cameraman on the 1934 film Kentucky Kernels, he would retire.