Robert Frank’s photographic masterpiece, ‘The Americans,’ still packs a punch at 50.

The 83 photographs in "The Americans" are for the most part far from flattering. But if the book were merely a chicly pessimistic condemnation of the country it examines, it would have faded away long ago. There is a lot of anger in the book, certainly, but there's much more to it. At its best, Frank's work possesses a love-hate tension that never resolves. The pictures fairly crackle with a finely focused ambivalence, a sense of mystery undispelled by repeated viewings.