Why are clips of old films always fast?

Persistence of vision (which makes still film frames appear to be in motion) only requires 16 frames per second to fool the eye, so that was the speed used for early films. When sound was introduced, the 16-frame-per-second speed caused warbling, so the standard was increased to 24 frames per second. [Harris Minter claims that the standard silent film speed was 18 frames per second.]

[Parenthetically, 16 fps means about 60 feet per minute. This is useful to know, since silent film lengths are often given in feet rather than minutes. Sometimes they are given in reels, which are 1000 feet. So a one-reeler would be about 16 minutes.]

When you see a silent movie, shot at 16 frames per second, projected at the faster rate, it looks "faster" but only because there aren't many 16 frame-per-second film projectors around. With modern videotape systems, the films-on-tape can be slowed back down.

To complicate matters more, the early cameras were hand-cranked: if the cameraman cranked too slow, the projector made the movie look too fast...and vice versa. Early cameramen had to keep a steady rhythm.

However, this is complicated by the fact that in the silent era, there was no universally "correct" film speed. The introduction of the 24-fps rate used today had to do with sound, as was said, not with the images. In the silent era, cameras were hand-operated, and so were most projectors. In addition to the obvious difficulties of maintaining a perfect rate by hand, the ability to speed up or slow down the progress of the film through the camera and projector was used for artistic effect. By undercranking (turning the crank slower and thus taking fewer frames per second) on shooting while projecting at normal speed, the action would speed up as more seconds of photographed time were compressed into a given number of seconds of projected time. Alternatively, overcranking would give the opposite effect -- slow motion. By cranking faster, the projectionist could speed up the action, while cranking slower on projection would slow down the action. The classic example of projectionist overcranking is during chases or other exciting scenes, to make the fast action seem even faster. I have heard that some films were even released with advice about how fast to crank during certain parts of the film. Also, shooting film undercranked would be used for certain stunts and special effects, giving the illusion of speed that wasn't actually present. [Another source reported that a PBS documentary series said films were sometimes undercranked to save film costs.]

One side effect of this method of shooting silent films is that any serious film guide that discusses silent films will not give running times for them, as that time could vary depending on the talent and mood of the projectionist. While the difference might be only a couple of minutes out of a couple of hours, printing a particular number of minutes as a running time for a silent film is misleading and can cause confusion. Typically, lengths are given in number of reels, or, when they really want to be careful, number of feet of film.

It's worth noting that the technology hasn't been forgotten, though, given one of the uses it's put to, maybe it should have been. Network TV is fond of slightly speeding up the rate at which they show films, thus permitting them to squeeze a long film into a time slot without cutting anything. This practice gets filmmakers very angry, as it damages any pacing or rhythm they put into the film.

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