FOR THE PAST 20 years, Roger Ballen has taken pictures of people in South Africa living on the margins of society. He photographs working, poor, and developmentally disabled people with faces distorted by the severe conditions of their lives, physical injuries, and mental retardation. The walls of his subjects' homes are typically barren except for occasional pictures, bare lightbulbs, and exposed wires. But Ballen isn't a social documentarian in any conventional sense. He doesn't merely capture the harsh reality of his subjects' lives as an objective fact, but rather presents startling scenes that disorient the viewer through their juxtaposition of the sublime and the banal. At times, in a manner reminiscent of Diane Arbus's photography, this seems to be primarily the work of Ballen's eye for the uncanny in the everyday. At other times, however, Ballen is like a film director, staging scenes with his subjects in their homes. In one picture, Scrap Collector Holding Globe, a man stands on the shredded mattress of a beat-up metal bed with a dog sleeping on his feet and a globe in his hands. Rather than romanticize the severity of the man's life in the name of pity or authenticity, Ballen sees an existential absurdity in it. The scrap collector is the protagonist in Ballen's drama. He is a figure of modern humankind overwhelmed, in the wake of God's death, by its responsibility for the world: nevertheless he searches for a modicum of value in a world that has been reduced to little more than junk on a scrap heap. In another picture, Herman with Hammer, Ballen presents the profile of a man holding a hammer pointed toward his face. With his mouth agape, he appears to be discussing with the hammer whether to smash in his own skull. Ballen and his subjects construct scenes reminiscent of Samuel Beckett's plays. They employ gestures, animals, and props as elements of artifice required not only to present life as it really is, but also to articulate how it barely is. Wed., Fri.-Sun., 11 a.m.- 5 p.m.; Thurs., 11 a.m.-7 p.m., 2626 Bancroft Way, Berk. $4-$8 (free first Thurs.). (510) 642-0808. (Clark Buckner)