Evening star., 1948-04-25
By Alexander J. Wedderburn
Curator Of Photography
The Sruithsonion Inxtitut;an

The Smithsonion Institution
Trick motion picture photography
Is not as difficult to accomplish as
IL may appear at first glance. Some
Of the most amusing and baffling
scenes in the professional films can
be duplicated by any one who has
. reasonably good movie camera.
The old standby scenes from the
days of Mack Sennett, where an
unguided vehicle would tear madly
through trafic with many near
crashes and hairbreadth escapes,
are just as effective today and have
been further supplemented by a
large repertoire of other tricks of
the trade that will "iven up" the
run-of-the-mill home movie.
1t should be emphasized that
while trick shots may be used for
comedy or dramatic effects, they
should be used only with discretion
and not abundance in one film. II
your film is simply a series Of one
trick shot after another your audi
ence will have hard time trying to
grasp what is taking place. On the
other hand. a well-placed shot Of
this kind will add a professional
touch to your work and win the ad-
miration of your friends and fellow
cameramen.
Perhaps the easiest and most pop
ular OF the trick effects, that can be
used by every one, are the slow
motion and fast Emotion shots. Since
most Of us are not shooting sound
on film, we will be operating at the
normal silent speed of 16 frames per
second. To slow down the action
the speed Of the camera may be
advanced to 80 frames per second,
which will double the amount OF
Aim normally used to record the
same scene. This will serve to re-
duce the speed of the action by one
half. To 60 even further, the
camera may be speeded up to "a
frames per second with a resulting
reduction of action speed by four
times. 1t must be remembered that
when the camera speed is increased
compensation must be made for the
reduction OF exposure that occurs.
PR instance, If you double the speed
OF - exposure, be sure to open the
iris diaphragm one full stop.
Valuable for Sports.
Slow motion can be utilized in
q number Of cases. Most important
will be its use when showing the
operation of mechanical devices,
or when 1t is desirable to slow down
. race, prizefght or other sports
event. Shooting from moving
automobile or boat at normal film
speed will usually result in excess
sively jerky movement on the screen
when the film is projected. This
problem may also be overcome to
. large extent by increasing the
camera speed.
On the other hand, you may wish
to speed up the pace Of the Aim.
If your script calls for a shrieking
windstorm, and you have only a
moderate breeze blowing, reduce the
camera speed to frames per sec
ond and the results may fool even
you when the picture goes on the
screen. Since this slowing down
Of camera speed will also affect the
exposure, the changeover to eight
frames will call for q one-stop de-
crease In the diaphragm opening.
Spectacular sunrises and sunsets
may be recorded in this way. After
all there Is no point in shooting a
static scene at 16 frames per second
when f1lm can be saved and the
dramatic effect heightened in this
manner. You should not attempt
to economic by shooting scenes OF
people, animals, cars and other
objects that move at . normal
pace In fast motion rs the result
ing film will be 1erky and ridicu-
lously unnatural.
At one time or another We have
all seen one of those comic westerns
where the comedian Is pursued
across the open plains by a band
of Indians. Suddenly he sees a
nearby tree with a trunk not much
thicker than q broomstick which
would not be big enough for dog
to hide behind. Nevertheless, to
our amusement, he rides his horse
UP to the sapling-and vanishes.
Impossible? Not to the photogra-
pher who knows the answer.
Mask Box Does All.
In addition to your camera you
will need only tripod and a mask
box for the lens to be able to ac-
complish this type of trick pho
Biography. In the case just mention
ed, the camera was set up with the
tree trunk bisecting the viewing
field. Then a masking slide was
inserted in the mask box so that
only the side Of the negative re-
cording the approach Of the rider
was exposed. Therefore, as he
reached the tree and passed on,
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