As painters, especially those of us who have worked with landsacapes over the years, it is practically impossible that we have not, to some degree, been influenced by photographs in the way we see the environment around us. Even those who eschew all photographic sources in favor of direct, out-in-the-fresh-air painting experiences cannot erase from their memories the many good, bad, and ugly landscape photographs they have been exposed to over the course of their painting lifetimes.
Imagine then if you will, what it must have been like for a man like French landscape painter Camille Corot. Born in 1796, he studied in Rome, and was influenced by another great French landscape artist, Nicolas Poussin who had done likewise. He was already an accomplished landscape painter when, in the mid 1800's the camera became a viable tool for capturing landscapes scenes. By the 1860's the exposure time for an outdoor photograph had dwindled to only a second or two. Suddenly landscape painters were confronted with a whole, new, undeniably accurate way of seeing their beloved world.
For Corot, the impact was profound. However instead of his work becoming more "realistic", the effect was that it became more "phtotographic" in the 1860's sense of the word. Film technology being what it was at the time, any movement in the landscape caused blurring, strong sunlight caused solid forms to become "feathery", and the combination of the two created an intergration of areas which served to unify the entire picture plane. The result was a new set of conventions for describing in paint the natural world, which in turn quickly paved the way for an even more revolutionary departure from convention--Impressionism.