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Magnetic
sound
tracks
Th
e
magn
e tic
tra cks depicted below in Fig
. 5
are cu stomary for dubbing 16 mm film.
Fig
.
5
Magnetic sound tracks
on
16
mm film
~u
u-u-
u-·
u
u
l
u
~
~
~
'
'
0
Ill
:
u
0
'
"~
11 11
' ""'
1
111:1 .1
1:1111111:11
11
1
11:11 111111:1111.
1
:
1111111:1111111:1111!
Equa
lizi
ng track
0.8 mm
Full
-w
idth tra
ck
2.5
mm
Eq
ualizing track 0.8 mm
Ha lf-w
idth
o
uts
i
de
t
rack
1.3
mm
Eq ualizing track
0.8 mm
Half-width
i
nside track 1.3 mm
As shown in
Fig.
7, the magnetic head for
the
2.5
mm
track
is
arranged su cceeding
the optical sound head (looking
in
the direction of film travel) in order to con-
form
to the interna
tional standard speci fying a
lead-lag
relation between sound
and picture
of
28
frames in the
case o
f
16 mm film with a full-width
magnetic
track. (The standard
lead-lag relation
between picture and sound
fo
r
optical
sound
film
is 26 frames.)
Feature
films with a
magnetic
sound
track
may
thus
be projected with
the
standard
lead-lag relation.
The 1.3 mm magnetic track is used when
it
is desired
for
certain
reasons to
retain the optical sound track, or when the optical sound track
is to
be
trans-
ferred to
the
half-width
magnetic
track with the possible addition of sound
from
other sources as well. lt may be recorded and reproduced with
the
magnetic
head
for the
2.5 mm
track. To
insure uniform wear upon
the
head, the inside
half-width track and the outside half-width track should be used alternately.
Optimum tona
l
quality
is obtained at a frame frequency of 24
frames
per sec.
This
corresponds
to
a
tape
speed of approx.
18.3
cm
per
sec.
8
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