While the light shows accompanying '60s rock shows can easily be ridiculed as hippie catnip, the LA-based Center for Visual Music proposes a more serious artistic heritage for the laser-led spectacles. Bruce Conner did a few back in the day, and lately artists like Bruce McClure have reinvestigated light shows' expressive potential. San Francisco remains ground zero for the art form; accordingly, Legendary Light Shows doubles as a tour of the long-gone ballrooms and bars that birthed SF psychedelia.