MOTION PICTURES
From an economic standpoint the motion picture business, including the
manufacture of film and other materials, and the production and showing
of pictures, is one of the major industries of the country.
In the past, entertainment has been the primary aim of motion pictures.
Now the field is broadening until it seems likely that their greatest
contribution to mankind will be in science, in industry, and in
education. Especially in research work are they valuable as cameras
have been devised that will take from 500 to 4000 pictures a second
of such subjects as a bullet piercing armor plate, a bird in flight,
mechanical motion, chemical action, or rapidly moving microscopic life.
The pictures can then be printed individually or can be projected as
slow motion pictures at only a fraction of the speed at which they were
taken, so the subject will seem to barely move. By analyzing motion
many extremely important facts have been learned. In industry such
pictures may be used to show where lost motion can be eliminated and
how an operation can be performed more efficiently. When it comes to
athletic sports, it is very difficult for the individual in football,
tennis or crew to realize just where his weakness lies, and what he
lacks in form, but when he sees himself on the screen as he actually
performs each individual movement, he can improve himself accordingly.
As it is generally recognized that knowledge is more quickly gained
by the visual method than in any other way, schools, colleges and
universities are using motion pictures more and more as an aid in
teaching all kinds of subjects. Often there is no sharp line between
educational and entertainment films. Dramatic films may be found
useful for art classes; science and travel films in the study of such
subjects as physical geography, geography and history. Films showing
such interesting phases of nature study as micro-organisms, the life
history of the bee, and the emerging of the butterfly are invaluable
in teaching biology and its allied sciences. Even in the lower grades,
animated drawings and maps and other types of pictures find their
places.
PRINCIPLE OF MOTION PICTURES
Motion picture cameras are arranged to take long rolls of film, often
several hundred feet in length. Standard film is 35 mm. (1⅜ inches)
wide. By turning a crank at a uniform rate of two revolutions a second,
the film is carried past the lens and eight exposures are made at
each revolution, or 16 a second, which uses about one foot of film.
A revolving shutter admits light to the film which stops during the
exposure. Each picture is made in ¹/₁₆ of a second and during this time
the shutter must open and close and a new section of film be drawn down
for the next exposure.
The film is developed, fixed, washed and dried and then printed on
positive film which in turn must be developed, fixed, washed, dried and
perhaps tinted.
The motion picture as seen on the screen is really a series or still
pictures projected at the rate of 16 a second. Each picture is on the
screen but a fraction of a second, the film not moving during this
instant. Then the rotating shutter covers the lens in the same way as
when the picture was being taken while a new view is brought down into
position. During the time between pictures, the screen is perfectly
dark, but because of “persistence of vision,” this is unnoticed so that
to the audience the projected still pictures make up the regular motion
picture with which they are familiar.
PICTURES IN THE HOME
The desire for making personal motion pictures is a very common one.
So irresistible is this appeal that almost everyone has long wished
for movies of the people who particularly interest them, movies that
they could make themselves and then show in their own homes. But until
recently there have been outstanding obstacles. Ordinary film is so
inflammable that many states have laws against its projection except in
fireproof booths. This often makes it impossible to show pictures in
a small school, church, or home. Also, standard film, which is taken
at the rate of 1 foot a second and then has to be printed on an equal
amount of positive film, makes the process expensive for those who wish
to make their own moving pictures.
To overcome these disadvantages simple motion picture cameras such as
the _Ciné-Kodak_ (Figure 9) are now made which use only a narrow width
safety film, 16 mm. (⅝ inch) wide. Some are operated by a crank the
same as professional cameras; others by a spring motor. With the type
using a motor, the camera can be held in the hands when the picture is
being taken.
[Illustration: Fig. 9]
Four hundred feet of this film gives the same period of projection when
used in the _Kodascope_ (Figure 10) as a thousand feet of ordinary
standard film, and as the film which is sent to the manufacturer for
development, is reversed to a positive by chemical treatment, printing
on a regular positive film is unnecessary. For this reason the expense
is only about ⅙ that of making standard size motion pictures.
FILM LIBRARIES. Although movies made in and around the home are so
completely fascinating in themselves, nevertheless, the Kodascope
offers another feature for the home entertainer. Hundreds of thousands
of feet of professionally made pictures have been leased for use
to the Kodascope Libraries, Inc.[11] Thus it is possible to rent
films to fit any type of entertainment—comedies, dramas, animated
cartoons, educational films—everything, in fact, most suitable for home
projection,—and new films are being added continually.
[Footnote 11: At 35 West 42nd Street, New York City.]
[Illustration: Fig. 10]