U.M. 3
Distance
Sca
le
Ind
i
cator
(
centr
al
oran
ge
lin
e)
-----Infrared
Inde
x " R
"-----------------
Distance Scale
The
distance
scale
indicates
the
distance
be-
tween
the
focused
subject
and
the
film
plane
.
The scale is
necessary
for
checking
the
depth
-
of
-
field,
for
infrared
photography
and
flash
photography
.
•
The
correct
position
of
the
scale,
where
the
distance
is a
one-digit
figure,
is in
the
middle
of
the
figure;
if
it
is a
two
·
digit
f
ig
ure
,
it
is
between
the
two
figures;
and
if it
is a
thre
e-
digit
figure,
it
is in
the
middle
of
the
ce
nt
ral
fig
ur
e.
32
Infrared
Index
"R"
For
infrared
photography,
correction
of
the
distance
scale is
necessary
because
the
focal
position
deviates
a
little
from
ordinary
photog-
raphy
.
Make
ordinary
focusing
first,
then
adjust
that
distance
scale
to
the
infrared
mark
"R
" . For
instance
,
if
the
distance
scale
reads
!Om
after
focusing,
merely
s
hift
the
10
scale
to " R " pos
ition
.
•
The
pos
ition
of
" R" is scaled acc
ordin
g
to
the
use
of
the
standard
of
a
film
with
th
e hig
hest
sen s
itivity
of
a wave leng
th
of
about
800m
µ
and
infrared
filter
(
for
example
, KODAK IR
135
film
and WRATTEN
87
filter
).
Film Plane
Mark
The
lens
distance
index
is scaled by
mea
s
ur
-
ing
the
distance
from
the
film
position.
Thus
,
in
case
the
focusing
is
done
by
actual
measure
-
ment,
measure
from
the
film
plane
ma
rk and
transfer
this
distance
to
the
lens
distance
index
.
•
Traces
of
water
bubbles
cannot
be
entirely
removed
from
glass
used
for
high
quality
lenses
because
of
the
manufacturing
process
.
Lens
bubbles
will
not
at
all
affect
the
sharp
-
ness
of
the
picture.
33