American Cinematographer - October 1968 - 40

MULTIPLE EXPOSURE TECHNIQUES
Several classic methods for creating Special
Effects-with and without an Optical Printer
By

NOVO

So-called "Trick Photography" used
in achieving special effects takes many
forms its mystifying wonders to per¬
form. The most commonly used is the
"Double Exposure." Anyone who has
ever taken a snap-shot with a hand
camera, knows what is meant by a
double exposure-it is simply two or
more photographs made on the same
piece of film. Whereas the double
exposure made with the hand camera
is usually unintentional, in motion pic¬
tures the Double Exposure is a tech¬
nique used quite frequently, and it is
done deliberately.
Most animation cameras are
equipped with a dissolve shutter at¬
tachment. This is a device which en¬
ables the operator to change the lens
aperture from wide open to completely
closed. When the shutter is in the wide
open position, that is said to be nor¬
mal. When the shutter is in the closed
position, no light can pass through the
lens and, of course, the film will not be

exposed. Between the wide open and
the closed positions practically any
variation of light intensity can be per¬
mitted to pass through the lens, making
possible a double exposure on any
degree intensity desired.
The mechanics of the double ex¬
posure are quite simple. On the first
run of the film through the camera we
might photograph a background scene
for the desired amount of footage. The
dissolve shutter is then closed and the
film is wound back to the starting point.
Now the controls are reversed so that
the film will run forward once again.
The dissolve shutter is opened to the
wide open position and a second im¬
age is photographed, but this time
over a black card. Otherwise the orig¬
inal background already photographed
would become over-exposed.
If the second image is to stand out
very clearly against the background,
the dissolve shutter might be left in
the wide open position. However,

should the shutter be partially closed,
the second image will be more or less
transparent, depending on how far the
shutter is closed. The shutter is cali¬
brated from zero to 170 degrees. At

A standard 35mm optical printer, embodying
a camera and projector with lenses facing
each other.

Diagrams detailing the First Run and Second Run stages for combining a live action scene with animation. In the First Run stage, (LEFT) a Fine
Grain Negative of the live action and a high contrast positive of the animation are threaded into the projector portion of the Optical Printer,
while the camera recording portion is loaded with Fine Grain Duplicating Positive film to make a Master Positive of the live action, with an
unexposed area where the animated character is to appear. In the Second Run stage (RIGHT) A Fine Grain Negative of the animation and the
High Contrast Negative of the animation are run through so that the camera can record a composite of live action and animation.

n« siu>m tttMTtvs
UVt ACTIO*

PROJECTOR

HIGH CWmSAST fOSIWf
0»

American Cinematographer - October 1968

Table of Contents for the Digital Edition of American Cinematographer - October 1968