If you're in San Francisco tonight, you have a rare chance to witness the early days of Star Trek and Star Wars fandom. A new documentary, Back to Space-Con, is showing at the Balboa Theater at 7 PM.

The documentary, which already had one showing at a small theater in Oakland, includes tons of footage of 1970s conventions, including some amazingly DIY early costumes. (Papier mache Stormtrooper helmets! Glued-on Klingon eyebrows!) Witness the ardor of early fans who kept Star Trek alive and helped turn Star Wars into the enduring phenomenon we obsess over today.