American Cinematographer - December 1960 - 50

i reversal printing 1
i and processing

generally of too high contrast for good
television reproduction. Original re¬
versal color films usually will repro¬
duce satisfactorily.
Color prints should be balanced
for arc projection as color receivers
are adjusted to a white color tempera¬
ture of 6500 degrees Kelvin. Prints
should be carefully color balanced
from scene to scene, and "whites" or
"greys" in highlights or shadows
should be neutral in color. Prints
should be timed dark enough to re¬
produce good color saturation, with
grey scale density values being about

the same as those given for the best
results in black-and-white.
A&B printing from color negatives
is recommended for making dissolves
and fades, thus avoiding the use of
intercut second generation material.
Black-and-white prints from color
negatives should be made from a
panchromatic master positive and
duplicate negative. The black-andwhite print from the duplicate nega¬
tive should be made to the specifica¬
tions for black-and-white television
prints outlined previously. ■

AN INFRARED SELF-MATTING PROCESS
Continued from Page 741

- * Work Prints *
- * Color-to-Color Prints *
" * Color-to-B & W Prints*
-» Raw Stock *

Fastax Sarvice
A&B Roll Prints
Fades-Dissolves *'■
Timed Prints

1

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this velour with sheet aluminum we
more than doubled its reflection of in¬
frared rays. This, of course, is quite
logical since infrared rays are heat
waves and bounce back from aluminum
foil or any other polished metal.
The best infrared "light" source for
our spectrum range, we have found
through trial and error, is the conven¬
tional incandescent lamp. There are
many other sources of infrared waves,
but unfortunately most of them are
above 900 m/x, and hence beyond the
infrared film sensitivity and impracti¬
cal for our purposes.
The two curves in Fig. 2 explain the
core of the process in a graphic way.
The solid line represents the sensitivity
of the infrared film, which is seen to be
most sensitive in the areas between 700
and 900 m/x. The broken line is the
transmission curve of the dichroic filter
coating for foreground lighting, and as
we see, it cuts off very sharply just
within the 700 m/x region where it is
needed most, while the visible trans¬
mission is hardly affected.
Thus the black background is pre¬
pared and "illuminated" with infrared
rays in such a manner as to give a good
exposure on the infrared film stock but
negligible exposure on the visual film
stock.
Foreground Lighting

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Concerning the visual side of the
process, it is necessary to expose the
panchromatic film stock but at the
same time avoid exposing the infrared
stock with any of the foreground action.
Therefore the infrared portion of the
spectrum must be prevented from hit¬
ting the foreground action because if it
should, we would get an exposure of the

foreground action on the infrared stock.
It is possible today, with improve¬
ment of techniques in the field of di¬
chroic coatings, to prepare a coating
which to a high degree will cut out any
desired part of the spectrum. In our
case we were trying to prevent a par¬
ticular portion of the spectrum from
lighting the foreground to which the
infrared film stock is sensitive, namely
700 to 900 m/x.
Special dichroic coatings were de¬
vised for the Fresnel lenses of our stu¬
dio lights so that the infrared waves be¬
tween 700 and 900 m/x are not allowed
to pass through, while the remainder
of the spectrum is practically undis¬
turbed. Neither the eye nor the pan¬
chromatic film stock is affected because
what we have eliminated was invisible
anyway.
Thus we do not have infrared rays
hitting the foreground, but we do have
infrared rays hitting the background.
To be more specific, the foreground is
lit with light minus infrared rays and
the background is lit with light plus
infrared rays.
Combining of Elements
The next step is to record these two
elements on two pieces of film. In order
to have an exactly identical picture, it
is essential that these two elements
should be exposed through one lens.
Figs. 3 and 4 show how the light passes
through the camera lens and thence to
the film:
(A) Light passes through the lens
and to the film.
(B) If we insert a piece of glass be¬
tween lens and film, the light still
passes through just as before.
(C) If we coat this piece of glass

AMERICAN CINEMATOGRAPHER
American Cinematographer - December 1960

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