It is hard to know what is myth, but it is said that films moved up from that 16-18 frames per second average to 24 frames in order to get smooth sound! not for the purpose of some science of sight (as we are generally taught.)

There is a group (mentioned in the next document) named the EDCF (European Digital Cinema Forum, part of whose work has been to keep the Hollywood powers-that-be aware that there are different needs outside the US. A most obvious example is that much of the music recorded around the world is recorded at 25 frames per second, not 30 (or variations of 25 and 30 to get away from phase beating from the electricity pulse, like 19.96....) These recordings have to be changed in some way by US post houses, such that the original pitch is changed or edited in some fashion.

The sub-group that pushed this was headed by Kommer Kleijn, who successfully got attention and results on an international level for this aspect, as well as lower and high speed alternative display frame rates. Here is a presentation that he gave a couple years ago: Flexibility in Frame Rates. (He mentions IMAGO in the first slide, which is the European Association of Cinematographers.)

As part of this work on behalf of archivists the world over, he worked with the chief engineer at the French and American server company Doremi, Francois HELT. They gave a demonstration 18 months ago that showed what could be done with projectors and old material. They came across the idea that 24*3, which is a natural frame rate in the digital projector, could be utilized to show 18*4. We all sat entranced while they played +100 year old, converted-to-digital films, via a digital projector. We saw some of the first camera tricks for movies from before and shortly after 1900.

I can't say enough nice things about the EDCF, who will gladly allow membership rights to interested parties for a relatively low fee.

Never underestimate their intelligence, always underestimate their knowledge.

Frank Delaney ~ Ireland