50Hz is below the flicker fusion threshold for most people. Even 60Hz visibly flickers for many people. Silent movies were shot and projected at many different

50Hz is below the flicker fusion threshold for most people. Even 60Hz visibly flickers for many people. Silent movies were shot and projected at many different framerates. Some early silent movies were shot at 18fps, but the average frame rate increased over time, and the standard 24fps was picked as a compromise that was around the average frame rate at which films were displayed at that time.