Peter Henry Emerson (1856-1936) was a leading English photographer who spearheaded a style he termed "naturalistic photography." He argued for photography as a fine art, encouraged his colleagues to use nature as their standard, and introduced the theory of "differential focusing," whereby the main subject was in focus and everything else fell into moderate softness.<BR>Many young Americans admired Emerson's work, forming a movement of naturalistic photography in this country that lasted from the 1890s to about 1930. Like Emerson, they emphasized the beauty of Mother Nature and humankind's harmony with her, photographing the land in all its seasons. Among the photographers whose work is included are Edward S. Curtis, Rudolf Eickemeyer, Alfred Stieglitz, and Doris Ulman.