American Cinematographer - December 1950 - 36

MOVIOLA
FILM EDITING EQUIPMENT
16MM. ~ 35MM.
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MOVIOLA

MANUFACTURING

1451 Gordon St.

*

CO.

Hollywood 28, Calif.

/^HFH^rERS
^

Jn WurU-Wirl'z Uss

Produce moonlight and night effects
in daytime*fog scenes*diffused focus
and many other effects.
Information mailed on request.

SCHEIBE FILTERS COMPANY
ORIGINATORS OF EFFECT FILTERS
618 N. San Vicente Blvd.
Hollywood 46, Calif.

Trends
Directors of photography,
camera department heads,
industrial and television film
producers, film laboratory
heads-these men and their
assistants naturally are coverto-cover readers of Ameri¬
can Cinematographer because
they must keep informed on
motion picture production
trends, new cinematographic
equipment, new techniques-
which today, more than ever,
is "must" news.

When appearing next to
this important "must"
news, advertising in this
magazine gains prestige
and importance.

AMERICAN CINEMATOGRAPHER
Advertising Department
1782 No. Orange Drive, Hollywood 28, Calif.

440

*

AMERICAN CINEMATOGRAPHER

it will shine fully on all parts of the
camera-side of the subject's face, and
consequently will have a relatively high
exposure value. If the keylight were
located well around behind the subject
(assume that the subject is facing the
camera), it will shine on possibly only
one-fourth of the subject's face, there¬
by leaving the other three-fourths in
shadow. In this location the keylight
would have a much lower effective illu¬
mination value.
Since the relative location of the keylight has an effect on the exposure value,
it is desirable to classify the keylight as
1. Keylight located in a position ap¬
proximately behind the camera. This
is a o° Keylight. (See Figure 3.)
2. Keylight located in a position roughly
450 above the camera or to one side
of the camera. This is a 450 Keylight.
3. Keylight located roughly overhead,
or to one side of the subject. This
is a go° Keylight.
4. Keylight located somewhat around
behind the subject. This is a 135°
Keylight.
Any keylight can be classified as be¬
longing in one of the four groups.
If a bright light is located further
around behind the subject than a 1350
position, then it cannot qualify as a keylight. In such a position its effect on
a subject is that of a back-light or a
line-light only.
The keylight source is usually very
easy to locate. Outdoors it is generally
the sun. If the subject is located in the
shade, the keylight usually comes from
an area of sky. If the subject is in the
open, and the sky is overcast, the keylight may usually be considered as being
located about 450 above the camera.
In nearly all photography it will be
found that the 450 keylight is by far
the most common. In studio work the
keylight is wherever the cinematogra¬
pher chooses to place it, however the 450
location seems to be frequently used.
After an intensive study had been
made of the properties of the keylight,
it seemed desirable to design an exposure
meter which would be directly adapted
to those properties. This was accom¬
plished.
The result was the "Keylite" meter
shown in Figure 2. This meter takes
into account the two basically important
qualities of the keylight: 1) The inten¬
sity projected to subject's position. 2)
The relative location of keylight source.
This meter differs from an ordinary
exposure meter in several important re¬
spects. The light collector is so designed
that the meter may be pointed directly
at an intense light source without dam¬
age to the instrument. The computer
dials are designed so as to take into
*

DECEMBER,

1950

account the effective value of the keylight illumination.
The "Keylite" meter is very easy to
use. Generally used at subject's location,
it is pointed directly toward keylight
source. If desired, the meter may be
aimed in various directions until the
maximum reading for keylight is noted
on the pointer dial. This feature affords
confidence in the use of the meter be¬
cause the maximum reading is always
the significant reading. The light inten¬
sity in foot-candle units is noted. This
value is used on the computer dials which
form an integral part of the meter. The
relative location of keylight source is
classihied by the operator and that factor
is also used on the computer dial. The
film speed factor is, of course, also pro¬
vided for on the dials.
The computer then shows the answer
in terms of appropriate lens aperture
(F-stop) for any given shutter time.
The result is perfectly uniform and de¬
sirable exposures for every scene. The
"Keylite" meter handles black and white
photography and color photography
equally well. As a matter of fact this
meter seems to be ideally suited to color
photography. The natural characteristics
of the meter just suit the unique and
exacting requirements of color films.
The "Keylite" meter is quite versa¬
tile. It covers a range of light intensities
from very low levels indoors to the
brightest sunlight outdoors. It handles
all commonly used film speeds. It covers
the useful range of lens aperatures and
shutter times. The meter can be used to
advantage not only as an exposure con¬
trol meter, but also as an indicator of
illumination contrast. By use of the
meter, illumination contrasts can be
easily measured, and consequently steps
can be taken to keep these contrasts at
appropriate values.
It has been found that measurement
of the keylight for exposure control pur¬
poses serves to eliminate the effects of
a number of variables which sometimes
tend to confuse the results obtained with
an ordinary reflected-light meter. Such
variables as change in composition of
subject, change in area of included sky,
color of subject, etc., have no effect on
the operation of the "Keylite" meter
because it does not "look at" the sub¬
ject. The meter "looks at" the keylight
source, which is the prime factor in
exposure control.
Use of the "Keylite" meter, over an
extended period of time in practical
photography, has consistently indicated
that it is an instrument which can be
of great assistance to any photographer,
for motion pictures or stills, color or
black and white, studio use or outdoors.
American Cinematographer - December 1950

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