Fascinating -- I'd always heard that 24 fps developed as a US film standard compared to 25 fps in Europe because of the difference in AC power frequency (24 and 60 being a pretty straightforward integer ratio). And yet, during this time, LA became firmly entrenched as the center of the American film industry while producing 24 fps films. I wonder how that squares -- was this something people had to deal with, or does this article possibly overstate how widespread 50 Hz power was?
The power frequency isn't that relevant for film, since it just powers motors on the cameras and projectors (or often just hand cranked). In fact, prior to the introduction of sound in films, the exact playback speed wasn't as important, and cinemas often varied.
Where it becomes relevant is for television, and in both cases the refresh rate matches the mains frequency. PAL is 50Hz interlaced, and NTSC is 60Hz interlaced.
I've heard of European broadcasters speeding up a film slightly so that it's 25 fps instead of 24. Thus the same movie could be several minutes shorter on European broadcast TV. As long as the speed difference is small enough, people don't notice.
Digressing a bit from the power grid, but American broadcasters will often speed up older shows (e.g. Friends reruns) because an hour long block of TV has more commercials now than it did in the 90s.
I've always noticed this in the PAL DVD releases of The Shield compared to the NTSC captures. In PAL, the music and voices are noticeably "sped up", mostly noticeable by the pitch shift.
This article covers the topic in more detail, but the general gist is that the film speed was controlled by the projectionist not the camera man recording the film, which was a set speed and powered by hand:
Nah, the 24 frames is the lowest frame rate before we sense the individual images. Leads to less film usage.
Note btw that we need 60 frames to get lifelike.
And gamers often want higher because the input sampling of a game is hooked up to the frame rate, so the higher the rate the more responsive the controls are...
I went to film school in Finland around 2000, and I remember that 25 fps was the preferred production and projection rate for 35mm. I got the impression that this was common practice elsewhere in Europe as well, but I don't know for sure.
I think the point is the film framerate was chosen to match the TV framerate, not the other way around.
Before TVs were invented, we had actual films being rotated by hand crank or by a motor - their fps is independent of electrical mains. But cathode ray tube TVs were made to match mains frequency. Then to avoid having to do some kind of conversion, it was easier to film your movies to match TVs.
Right, standardizing on 25 fps in Europe came from PAL's 25/50Hz rate.
I think 24 fps for sound film originally arose from the requirements of the optical soundtrack: slower running 35mm film wouldn't have enough resolution for decent sound quality. That's my guess anyway.
Silent films were often shot on slower rates around 16-18 fps (which explains the widespread comic "speed-up" look for video copies of silent movies, as the transfer was done the easy way by playing it back at 24).
Actually it has to do with how film is shot. Lightbulbs pulse at mains frequency, shoot indoors at 24fps in 50hz land and you'll get a horrible 1hz strobe effect.
There are tricks you can do with shutter angle that negate this, but they are beyond the scope of this comment.
