By Cheryl Eddy

IT'S ONE THING to be a casual hoarder of, say, Freddy Krueger dolls. It's another thing to define your life by your hobby. At some point it ceases to be a hobby and becomes an obsession. Take, for example, Elizabeth Tashjian, self-described "nut culturist" and former curator of the Nut Museum in Old Lyme, Conn. Her unusual life – stumping Nipsey Russell on To Tell the Truth, charming Johnny Carson with her "nut anthem," even earning the respect of Katharine Hepburn – unspools in Don Bernier's In a Nutshell: A Portrait of Elizabeth Tashjian, an affectionate doc that's among the highlights of this year's San Francisco Documentary Film Festival.

Fans of Grey Gardens will recognize elements of Tashjian's tale: she comes from a wealthy family, had a codependent relationship with her mother, and grew old in a mansion she couldn't afford to maintain, to the annoyance of her moneyed neighbors. In her Nut Lady heyday, Tashjian welcomed busloads of tourists into her living room, proudly showing off her stacks of nut-themed artwork; later in life her physical health declined, along with the condition of her once-grand home. In a Nutshell balances its more poignant moments with unbridled appreciation of Tashjian's eccentric spirit, taking a joyous turn when her beloved nut collection is entrusted to the Museum Studies Department at Connecticut College. (It later goes on display as part of an exhibition honoring her "visionary art.")

DocFest's obsession with obsession continues in Other People's Pictures, Lorca Sheppard and Cabot Philbrick's insightful study of Chelsea Flea Market denizens who spend every weekend pawing through stacks of old photographs. The most intriguing collectors search within very specific, very personal themes. One Holocaust survivor's son seeks what he calls "banality of evil" images and has amassed a huge array of shots depicting uniformed Nazis chilling in social settings. Other People's Pictures is co-billed with Monica Bigler and Sarah Prior's Buried in the Backyard, which affirms that Americans are still paranoid enough to build bomb shelters (and wear unironic T-shirts that read, "I have a shelter – if you see me running, try to keep up"). Less straightforward but equally compelling is Michael Gitlin's The Birdpeople, which details the hunt for the elusive ivory-billed woodpecker, the equivalent of Bigfoot in ornithology circles.

Less tangible pursuits are embarked on in The Education of Shelby Knox, Marion Lipschutz and Rose Rosenblatt's take on a spunky Lubbock, Texas, high schooler who finds her calling as a crusader for sex education (the current district policy is "abstinence only," despite the town's high teen pregnancy and STD rates). Complicating matters, Knox is a devout Christian and daughter to ultraconservative parents, not to mention surrounded by close-minded townspeople. If any DocFest movie will have you yelling at the screen, the emotional Shelby Knox is probably it – watch out for Knox's misguided youth minister, who achieves near banality-of-evil heights himself when he suggests that gays and murderers are the same in Jesus's eyes.

Cheering is a more likely reaction to Pedro Carvala's POPaganda: The Art and Crimes of Ron English. Though the film celebrates English's paintings – twisted renderings of pop icons like Marilyn Monroe, Mickey Mouse, and Homer Simpson – the rebel artist's heart clearly belongs to the pursuit of "billboard liberation." As Carvala's camera whirrs, English scales buildings to bring his art (shaming targets like McDonald's and Camel cigarettes) to the masses. He's an engaging figure, which makes the film even more entertaining – though POPaganda includes footage of English and his wife on a talk show, discussing how his billboard fixation has strained their marriage.

The spiritual side of obsession surfaces in DocFest's opening night film, Mana: Beyond Belief, Peter Friedman and Roger Manley's collage of vignettes about "power objects" – including low-rider cars, the Shroud of Turin, and (in possibly the funniest sequence in any single DocFest film) the flag that flies over the United States Capitol. A more personal objective emerges in Velcrow Ripper's ScaredSacred, which traces the filmmaker's global quest to find "the sacred inside the scared" in places where hope seems impossible: Hiroshima; Bhopal, India; New York City's World Trade Center ruins; the barrier wall between Israel and Palestine.

As many of these films prove, an obsession denied can lead to despair and lingering heartbreak. Tashjian's nut-encrusted downfall is sad indeed, but no DocFest selection is more moving, or more melancholy, than The Loss of Nameless Things, Bill Rose's exploration of the life of playwright Oakley Hall III. Creative-minded folks in particular will shudder at Hall's bizarre tragedy, a fall from a bridge that he survived – albeit with his genius completely lost in a near-lobotomizing head injury. Though misty-eyed recollections by Hall's former theater colleagues paint a picture of a fiercely talented man who might as well have died in his accident, present-day interviews with Hall – newly invigorated by the 2002 world premiere of his 1978 would-be masterpiece – allow optimism at last to filter in.

San Francisco Documentary Film Festival runs May 12-22. For venue and ticket information, see Openings, in Film listings, or go to www.sfindie.com.