The leader of the naturalistic movement in photography, which
emerged in 1880s, was Peter Henry Emerson (1856-1936)
Emerson's main claim was that one should treat photography
as a legitimate art in its own right, rather than seek to imitate
other art forms; imitation was not needed - it could confer its
own legitimacy without it.
Emerson claimed that true photographic art was possible only
through exploiting the camera’s ability to capture reality in a
direct way.
The rules of naturalism were: no “faking” by means of lighting,
posing, costumes or props; no retouching. A so called
“scientific focusing” technique was promoted, which imitated
the way the eye perceives a scene: sharply focused on the
main subject, with the foreground and the background slightly
out of focus.