40 years ago a film buff took all he could remember of Buck Rogers, Seven Samurai, World War II movies (both sides), and the Masterplots guide to The Hero with 1000 Faces, and made a movie with lotsa battles, unprecedented special effects, and magnificent scenery that the actors sometimes blocked our view of. That’s when sf became sci-fi.

ETA: It was also the year that Terry Brooks cut the interesting parts out of Lord of the Rings and created not only a bestseller but a template for the infinite replication of fantasy product. Anus mirabilis, or something.