"Modernism photography sticks to the ‘rules’ and postmodernism rejects the ‘rules’. Modern photography is filled with warmth and passion, while post-modern photography is said to be dispassionate and cold.Postmodernism is anything that challenges modern concepts and concerns"
Beginning in the mid-to-late 1960s, when Abstract Expressionism had already been falling out of public favor for some time, many artists turned increasingly toward mixed-media art forms, such as Conceptualism, Super-Realism and Neo-Expressionism, which were precursors to Postmodern art.
In some media, what is meant by postmodern is clear and easy enough to point to: it is the rejection of the utopian aspects of modernism, and particularly of the attempt to express that utopianism in ideal or absolute form—the kind experienced in Bauhaus architecture or in minimalist painting. Postmodernism is an attempt to muddy lines drawn fals clear.
photo: Lois Greenfield
Good article on postmodernsm in photography http://www.arthistoryunstuffed.com/postmodernism-in-photography/