UNSTRUNG HEROES (1995) ** 3/4.

Actress Diane Keaton, who dresses like Buster Keaton, has directed a peculiar feature-length documentary ("Heaven"), a nice film for cable ("Wildflower") and some TV episodes.

With "Unstrung Heroes," her first fictional feature for the big screen, she joins the increasing roster of women directors that must be paid attention to because they have something to say. I just caught a glimpse of Carol Channing on C-Span. Reacting to the criticism of Hollywood for its violence and sex, she said that those are not the things that involve the audience, but that familiar situations do, like the death of a father. How true.

The movie is set in early 1960s Los Angeles, within the Lidz family. Father Sid is an inventor of outlandish items that may or may not work. He got his inpiration at the 1939 New York World's Fair, the landmark one that celebrated a future made rosy by science, machines and gadgets. Optimist Sid had kept that faith indomitably: "There's nothing that science can't fix" he says. He is so wrapped up in his projects that he makes an unorthodox father of his two kids, especially 12-year old Steven. Where other well-meaning dads can impose fishing or baseball on their children, Sid does this with electronics and thingamajigs.

Sweet Mrs. Lidz is an exemplary mother and a believer in her husband's genius. But neither Sid's vast medical reading nor medical science can do anything for her terminal cancer. As relatives cluster, all Jewish and all pleasantly colorful, we meet Sid's two strange brothers : Danny, a paranoid hulk who sees conspiracies everywhere, down to anti-Semitic echoes in the slogan "I Like Ike," and moonfaced Arthur, a scavenger of you-name-it-he's got it discards which, together with mountainous piles of newspaper bundles (" I haven't read them yet") make the cavernous Danny-Arthur apartment look like a Kafkaesque dedalus. He also places absurd memorabilia on grandma's grave.

When young Steven learns that his mother is dying, he seeks instinctively solace from his uncles. Their very weirdness helps the three bond. But did I say weirdness? Did someone say quirky? Or dysfunctional? Or eccentric? No, the right word for the uncles is plain "meshuga." Yet it is this very madness that, lined with undemonstrative affection, tightens -- in unsentimental ways -- the relationship among them. One of the by-products is that Steven, who has non-believing parents, is influenced by the uncles' Jewish faith and insists on a Bar-Mitzvah.

The two nuts also decide that "Steven" is too ordinary a name, so they rename him Franz, as in Franz Liszt, to the boy's delight. And among other happenings, Steven/Franz perpetrates a hoax on a fire inspector. He also sings "The International" while his schoolmates recite the Pledge of Allegiance.

The mixture of comedy, the bizarre and tragedy is well melded in the warm, loving script by Richard LaGravenese ("The Little Princess," "The Bridges of Madison County"). It has very good moments of un-soupy pathos and of unforced laughter.

Among the former is the touchingly sober treatment of the dying mother and the helpless father. Among the latter, a bit where Sid has hired a housekeeper who botches the kids' breakfast and makes the little girl say that the eggs look like something that came out of her nose. Or an argument about a 79 (sic) rpm record salvaged by Arthur. Or Mother opening a messy package of pancakes cooked by Steven, now in residence with the uncles. She exlaims: "My God! he's becoming one of them!"

What works less well is the to-and-fro structure of the movie's rather invertebrate first part, and the common scourge in films today, insufficiently sharp sound recording of actors who do not enunciate well to start with. Yet most of this is made up by the excellence of the acting, the 1960's atmosphere, the score, and the photography by Phedon Papamichael, a native of Athens, Greece, who came to the United States in 1983. He has a knack for close-ups and medium shots that focus your attention yet have none of television's blah and routine look.

The film raises a variety if points. Number one is that Angie McDowell is far better as a dying mother than as a healthy lover. Two is that Steven runs a 16mm Bolex camera unnoticed by the nearby subject (the housekeeper), yet those spring-loaded cameras do make an audible whir. Three is that we never find out how Dad manages to make what seems to be a decent living. Four is a weird connection: in some ways as the movie reminds one of the excellent but unsuccessful "King of the Hill" by Steven Soderbergh who gave Ms. McDowell her big chance in "sex, lies and videotape."

Point Five is the PG rating. Few good films have it. But is "Unstrung Heroes" for youngsters? Over and above its funny-loony aspects, this is a sad picture. Should we burden youngsters with the motif of death-in-the-family when there is ample time for kids to come to grips with it?

I don't know, but so far as adults are concerned, this is a recommended movie.