10 Why are clips of old films always fast?
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This article is from the rec.arts.movies.past-films FAQ, by Evelyn C. Leeper evelynleeper@geocities.com with numerous contributions by others.
10 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.
[Thanks to Douglas Ferguson, ferguson@andy.bgsu.edu, and Peter Reiher,
reiher@ficus.cs.ucla.edu, for this answer.]
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