Pentax digital spotmeter - Page 14

The intermediate
numbers
9
-2
(90
-
20%
IRE)
indicate comparative
brightness based
on the 1OO%
"White
level."
These indices
represent
divisions
of
the
linear
gray
sca
le.
The
large orange triangular index between
3
and
4 is
the
Standard
Index,
in use on
most
light
meters,
which
shows
the
average
of optimum
f
ilm exposure
levels
(light
level obtained using
standard
ref lecting
surface,
ret
lectivity
ratio
of
1B%).
The
f
igure
"1:32"
at the
extreme
left
of
the scale
indicates
the contrast
ratio
between
lR
E
scale
1
and
10 The IRE
scales
from
1 to 10 cover 5 light
level numbers
Since an
increase of
one
EV
number
represents
a
doubling of light level, the contrast
ratio is 1
:32
Qs
=
32\
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