After emigrating to San Francisco in 1895 to work as a tutor for the son of Baron and Baroness J. Henrich von Schroeder, he taught himself photography. He was intrigued by the Chinese section of the city and photographed its inhabitants, from children to drug addicts, Due to his subjects' possible fear of his camera or their reluctance to have pictures taken, Genthe sometimes hid his camera. He also sometimes removed evidence of Western culture from these pictures, cropping or erasing as needed. About 200 of his Chinatown pictures survive, and these comprise the only known photographic depictions of the area before the 1906 earthquake.