Born in Cuba to an American father and English mother, Peter Henry Emerson returned to England at age 13 with his mother after the death of his father. He studied medicine, receiving a degree from Kings College in 1879. He began photographing the "peasants" who worked the land of Suffolk and Norfolk, attempting to record a way of life that had almost disappeared as a result of industrialization. He advocated a "naturalistic" approach to photography, rejecting the artificiality of constructed scenes made from several negatives and combined in the darkroom such as those by Robinson and Rejlander. He believed in photographing "real" people in their natural environments, and printed his negatives without manipulation.
Influenced by the theories of human vision proposed by German scientist Hermann von Helmholtz, he claimed that a naturalistic photograph should represent the world as the human eye can see it. He proposed his idea of "differential focusing," which involved placing only a selected part of the scene in sharp focus. His theories were controversial, adding to the lively debate about the role of photography in art. His soft-focus, relatively "pure" style was recognized by later Pictorialists such as Frederick Evans, Alvin Langdon Coburn and Alfred Stieglitz.
After abandoning his medical career in 1886, he began publishing his photographs in portfolios of platinum prints and photogravures. He published Life and Landscape on the Norfolk Broads with T. F. Goodall in 1886, and Pictures of East Anglian Life in 1888. His landmark manual Naturalistic Photography for Students of the Art appeared in 1889, but his arguments for photography as an independent art were retracted in 1890 with his release of The Death of Naturalistic Photography. Despite this, he received the Royal Photographic Society Progress Medal for work in artistic photography in 1895. Reviewing the third edition of Naturalistic Photography (1899) for Camera Notes, Alfred Stieglitz wrote that while the book "had struck a blow which shattered idols without mercy,"…"to it pictorial photography owes the stability which it now enjoys."