John Ridley's new film about Jimi Hendrix, Jimi: All Is by My Side, is not a biopic. At least not in the traditional sense. It isn't interested in the full sweep of the man's too-short life or in dutifully dropping the needle on his greatest hits. It's a snapshot of one year, an origin story about the moment in 1966-67 that Hendrix went from unknown backup musician playing half-empty New York clubs to the toast of London, on his way to becoming the most incendiary rock icon of his generation. Ridley, the Oscar-winning writer of 12 Years a Slave, makes his feature directorial debut here, and it's clear that he's a born filmmaker. He's also got a hell of an eye for casting. André Benjamin, from OutKast, is perfect as Hendrix, nailing his look (the teased-out nimbus of hair and groovy Carnaby Street threads) as well as his space-cadet cadences, his selfish dark side, and the way he comes alive on stage. When he plugs his Stratocaster into the amp, it's not just the instrument that becomes electrified, it's his whole being. The film's lack of such signature Hendrix tunes as ''Purple Haze'' may put off some — the filmmakers couldn't get the rights — but I'd argue that this obstacle forced Ridley to zig where most biopics zag. Which, when you think about it, is fitting for the story of a lefty who played his guitar upside down. B+