Tom Mix's favorite cameraman, Daniel Clark spent most of his career with Fox and its successor, 20th Century Fox. In the mid-'30s, he became involved with the purely technical aspects of cinematography, inventing a special blue filter to shield the still-sensitive eyes of the famed Dionne Quintuplets in The Country Doctor (1935). Clark earned a 1943 Scientific and Engineering Academy Award for "the development of a lens calibration system and the application of this system to exposure control in cinematography." ~ Hans J. Wollstein, All Movie Guide