PHOTOGRAPHING MONTANA, 1894-1928, by Donna M. Lucey (Alfred A. Knopf: $60; 250 pp.) Late in the 19th Century, a well-brought-up Englishwoman named Evelyn Cameron and her husband Ewen took themselves off to Montana to, of all things, breed polo ponies. That didn't work out, but what did was photography; Cameron took literally thousands of pictures, documenting the reality of life at the bleak edge of civilization as only someone who lived there fulltime could do. Rediscovered after half a century in a friend's basement, the best of Cameron's unsentimental yet invariably telling work is reproduced here, along with copious excerpts from her splendidly matter-of-fact diary. "We have all the troubles of Arctic explorers here," she wrote evenly, "but none of the credit."