Bull headed MGM's still photography department for four decades and is
considered the best portrait photographer working in the Golden Age of
the Hollyood studio system and photographed all the studio's major
stars over the years. He is best known for his portraits of Greta
Garbo, especially his iconic picture of the actress and the Sphinx.
As a young artist Bull was mentored by the noted Western artist, Charles M. Russell.
Bull claimed to have photographed Lon Chaney made up as Jesus Crist, but the portrait has been lost.
According to a 1941 syndicated column by John Chapman, Bull was identified as Greta Garbo's preferred portrait photographer. He would reportedly take an average of 200 stills of Garbo over the course of shooting a film.