American Cinematographer - October 1968 - 49

OF PERFORATIONS AND PITCH
By way of clarifying some of the confusion that may
exist regarding physical chaacteristics of various
film stocks-and the mysteries of "A" and "B" wind
16mm Films
16mm motion picture camera films
or films for duplicating purposes are
supplied with either a row of perfora¬
tions along one edge or with a row
of perforations along both edges. Ba¬
sically, most 16mm camera films are
furnished with two rows of perfora¬
tions for use in "silent" type cameras.
Those with one row are intended for
use in single-system cameras where
sound and picture are simultaneously
recorded, either optically or by means
of magnetic striping on the film. Single
perforated film is also used for mag¬
netic sound recording to be accom¬
plished after the film is processed.
Windings
The terms "A" and "B" windings
distinguish which side of a single per¬
forated film carries the perforations.
Generally, duplicating films used for
contact printing require winding "A"
while films used for projection printing
are supplied in winding "B". Single
perforated 16mm camera films are
supplied in "B" winding only. 16mm
printing films, reversal or positive type,
are supplied in both "A" and "B"
windings.
In the accompanying sketches the
film is wound on cores and the emul¬
sion side of the film faces the center
of the roll. When the roll is held so
that the outside or leader end of the
film leaves the roll at the top and
toward the right. Winding "A" has
the perforations along the edge of the
film toward the observer and Winding
"B" has the perforations along the
edge away from the observer.

16mm camera film intended for sub¬
sequent release printing is generally
furnished with short pitch (2994) per¬
forations. When films are being print¬
ed, the original camera film and the
unexposed printing stock pass over a
curved printing sprocket simultaneous¬
ly for exposure. Since the printing
stock is on the outside, the difference
in diameter of a few ten thousandths
of an inch is accommodated by giving
a shorter pitch between the perfora¬
tions of the film being duplicated.

Most printing or duplicating films,
either reversal or positive types, are,
therefore, supplied in long pitch.
Identification
In referring to a 16mm camera film
intended for direct projection the
term "PH22.5-1 964-2R-3000" is used.
The first set of numbers and date re¬
fers to the American Standards Asso¬
ciation specification sheet for this type
of perforation and the date on which
it was adopted. "2R" indicates that

fYPES OF PERFORATIONS
FILM TYPE

ASA PH22/NUMBERt

16mm (2R-2994)

PH22.110

Camera original intended for release printing, 2 rows perforations, short pitch.

16mm (1R-2994)

PH22.109

Same as above, except 1 row perforations.

16mm (2R-3000)

PH22.5

Camera original reversal intended for direct projection. Also printing or dupe
films, either reversal or positive types. 2 rows perforations, long pitch.

BRIEF DESCRIPTION*

16mm (1R-3000)

PH22.12

Same as above, except 1 row perforations.

35mm (BH-1866)

PH22.93

Bell-Howell negative perforation, short pitch.

35mm (BH-1870)

PH22.34

Bell-Howell negative perforation, long pitch.

35mm (KS-1866)

PH22.139

Kodak Standard positive perforation, short pitch.

35mm (KS-1870)

PH22.36

Kodak Standard positive perforation, long pitch.

35mm (DH-1870)

PH22.1

Dubray-Howell perforation, long pitch, used for various purposes.

35mm (CS-1870)

PH22.102

CinemaScope positive, long pitch.

65mm (KS-1866)

PH22.145

Camera negative, short pitch.

65mm (KS-1870)

PH22.118

Work print, long pitch.

70mm (KS-1870)

PH22.119

Release print, long pitch (perforated same as 65mm camera negative, extra space
on sides for magnetic sound tracks.)

tFilm dimensions are updated at intervals. Check latest American
Standards Association spec sheets for current data.

*The terms "negative" and "positive" refer to perforation types
only, not intended use.

16mm FILM DIMENSIONS
-E

Perforated
Two Edges

Pitch
Pitch is the distance from the lead¬
ing edge of one perforation to the
leading edge of the next and is ex¬
pressed in decimal inches. Motion pic¬
ture perforations are commonly re¬
ferred to as having either "long" or
"short" pitch.
16mm camera film of a reversal
type intended for direct projection is
usually supplied in long pitch (3000).

AMERICAN CINEMATOGRAPHER, OCTOBER 1968

FILM
16mm,
16mm,
16mm,
16mm,

2R-3000
1R-3000
1R-2994
2R-2994

ASA STAND.
PH22.5
PH22.12
PH22.109
PH22.110

FILM DIMENSIONS (Inches)
A
0.629
0.629
0.628
0.628

B
0.3000
0.3000
0.2994
0.2994

C
0.0720
0.0720
0.0720
0.0720

D
0.0500
0.0500
0.0500
0.0500

E
0.036
0.036
0.0355
0.0355

G
0.001

1
0.413

0.001

0.413

L*
30.00
30.00
29.94
29.94

'This dimension represents the length of any 100 consecutive perforation intervals.

765

R
0.010
0.010
0.010
0.010
American Cinematographer - October 1968

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