''Camille Claudel,'' showing at the Charles, is the story of Claudel's very long descent into madness. The film, two and one-half hours long, should run no more than 90 minutes, but director Bruno Nuyten apparently wanted us to share in all this agony, which we do.
Claudel, who lived from 1864 to 1943, was collaborator then mistress to Auguste Rodin, the French sculptor. He already had a family, but that didn't deter Claudel who, when Rodin refused to leave his wife and children, began her ride to hell.


