Now in its 15th year, the San Francisco Black Film Festival offers a globe-spanning selection of movies either by filmmakers of African descent or which feature actors or subjects representing the African diaspora. Over four days and about 70 feature-length and short films, the festival covers a lot of ground: haircuts and homosexuality, fluoride and the blues, and, in Impresa!, East African entrepreneurship in S.F. On Friday, Denise Ward-Brown's feature documentary Jim Crow to Barack Obama examines how issues surrounding race have evolved over the past century. It's followed at 4 p.m. by Jorge Hinojosa's fascinating documentary Iceberg Slim: Portrait of a Pimp, which looks at the life of the titular author of the 1969 book Pimp: The Story of My Life, which in many ways codified the template for 1970s pimp culture and the later gangsta culture. At 6 p.m. is Coming Back for More, Dutch filmmaker Willem Alkema's first-person documentary about tracking down the reclusive funk pioneer Sly Stone, whose band Sly and the Family Stone was born in our own Ingleside District. In addition to plenty of classic Stone jams, the film features Sly's first full-on interview in over two decades. And the evening closes with an 8 p.m. screening of Elias Mael's narrative feature Against the Grain, about a young man from West Oakland struggling with his past during his first year at an elite university.