Apple Final Cut Pro 5 - Manual (Page 1731)

380 Part V Appendixes
Frame Rate Limits: How Many Frames
per Second Is Best?
When recording an object in motion, there are practical reasons to limit the camera
frame rate:
 The limit of human perception: There is no reason to show more frames per second
than the viewer can perceive. The exact limit of human motion perception is still up
for scientific debate, but it is generally agreed that there is an upper threshold after
which people can’t appreciate the difference.
 Media cost and size: Film and video tape stock cost money. Higher frame rates require
more footage, and are more expensive to shoot. Editing and media management
becomes more difficult as the amount of raw media increases.
Recording High Frame Rates for Slow Motion Effects
Despite the increased cost and effort, there are cases where shooting higher frame rates
is useful. Slow motion effects are created by recording hundreds of frames per second
and then playing the same frames back at a slower rate. For example, a bullet shattering
a light bulb may take only a fraction of second, seeming almost instantaneous to
anyone watching. If a camera records the light bulb a thousand times per second and
then a projector plays the frames back at 24 fps, the movie on screen will take almost
40 times as long (1000 fps / 24 fps = 41.6 seconds). The higher the frame rate, the more
temporal (time) resolution your footage has, which means it can be slowed down to
show detailed moments that would otherwise be a blur. Shooting at high frame rates
also requires more light, because there is less time to expose each frame.
Recording Slow Frame Rates for Time-Lapse Photography
Slow frame rates are used for time-lapse photography, in which a scene is recorded
relatively slowly, perhaps one frame every second, hour, or day. This is useful when you
are trying to capture gradually changing events, such as growing plants, the movement
of clouds, or the rising and setting of the sun. When played back at standard frame
rates, events occur rapidly on screen and otherwise undetectable patterns emerge.
Stop-motion photography, traditional drawn animation, and computer rendering take a
similar approach. The point here is that the rate of creating a frame does not
necessarily correspond to the rate of playback. This is one of the most exciting
propositions of motion pictures and their ability to manipulate time: You can create
images at whatever rate suits you and play them back at a totally different speed.