1 The Director of Photography – an overview

38 Practical Cinematography
Figure 4.1 The decay of an image
on the human retina
Decay
of image
on retina
does the movement become truly believable, as continuous motion
and the flickering effect reduce to the point where it can be ignored.
Figure 4.1 shows a series of images as they decay, represented by the
vertical frames, and the frequency with which the images must be
replaced for the observer to believe that they are seeing a smooth,
continuous motion, represented by the horizontal frames.
Frame rates
Succession of images displayed on retina
At the turn of the century, a taking frame rate of 16 frames per second
(fps) was becoming common practice. At this time, both cameras and
projectors were still very much hand cranked and most were geared
such that a constant cranking speed of two turns per second resulted in
this frame rate, which was very convenient. Those in the industry who
were beginning to consider themselves artists would have preferred a
higher rate, since this reduced the flicker on the screen, hence the
phrase ‘going to the flicks’. The film producers and distributors, on the
other hand, were seriously opposed to an increase in frame rate, as this
would use more film and therefore put up costs. Little has changed.
By 1926, the American Society of Motion Picture Engineers (SMPT,
later the SMPTE) Standards and Nomenclature Committee recommended
camera cranking speeds as follows:
Regarding camera speed we recommend as a recommended practice: a
camera cranking speed of 60 feet per minute (16 fps), with a minimum
of 55 feet and a maximum of 65 feet when normal action is desired, in
connection with the Society of Motion Picture Engineers recommended
practice of 80 feet per minute projection speed (21 fps).
To recommend different taking and projection speeds may now seem
ridiculous, but what they were trying to do was to set a standard for a
frame rate that was perceived to be correct on viewing.Try turning the
sound off on your television and notice how the action suddenly seems
to be slower, despite your certain knowledge that it cannot be. It
would be uncharitable to think that the theatre owners were keen to