SAN FRANCISCO -- Yoko Ono was at the San Francisco Museum of Modern Art Friday to celebrate the opening of an exhibition of her art. Spanning more than 40 years, "Yes Yoko Ono" includes more than 150 works, objects, photographs, film, video, music and performance art, by the avant-garde artist. Among the collection is a piece called "Sky Piece for Jesus Christ," in which a chamber group plays a classical composition while other performers wrap them and their instruments in gauze bandages until it's impossible to play. Then they are carried offstage. Yoko Ono's art exhibition opens Saturday runs until Sept. 8. Ono, 69, is better known for her relationship with John Lennon than her artwork. Lennon was shot and killed by a deranged fan outside the couple's Manhattan apartment building in December 1980. The show, which opened two years ago at New York's Japan Society, is an effort to demystify Ono for the general public, said Clara Kim, one of the exhibit's organizers. "I hope this retrospective is one of the signals that she can finally be regarded for her own artwork, her own music, her own talents, her own voice," Kim said.