Sekonic Studio Deluxe L-28 C2 - Page 19

ment is
a method
of
determining
exposure
by
measuring incident
light,
assuming
that
ilre subject
reffects
18%
of its incident
light.
The
effective foot-candles
measured
by the
Lumis-
phere
to
determine
the
correct
exposure,
deternrines
the
mid-point
of
brightness.
Example:
Assume
that
by regular
measurement
with
the
Lumisphere
without
the
Slide,
the
needle
indicates
5OO foot-ca ndles. With
a
f
ilm
index
of
ASA
10,
the correct
exposure
is
midway
between
FlL
and
F16,
with
a shutter
speed
of
one
second.
When
the
"L"
m
ark
is set
to
500,
tlre
"
H
"
m
ark
points
to 16.
This
16
is
the
mid'point
of
brightness
ra
nge.
This
mea ns
th at
if
a
standard
18%
re'
flector
is measured
with
the
Lu m
igrid
under
the
sa
me con-
ditions,
the needle
will
point
to
16.
ln
determining
ex-
posure with
tirc
Lumisphere
or
Lumi-
grid,
the
r'H"
mark
always
indicates
the
center
of
the
brightness
ra
nge,
regardless
of whether
the,'H',
or
,.L,,
mark
was
used
in determining
the
correct
exposure.
f
f
the
" H"
mark
is
off
scale
when
the
..L,,
mark
is
set
to
the
needle,
the
light
level
is
so low
th
at
no
usable
reading
ca
n
be obtained
with the
Lumi-
grid.
In other words,
ref lected
light
measurement
with
the
Lumigrid is
possible
only
when
the
inten-
sity
of
incident
light
exceeds
I25
foot-ca
ndles.
There
are
three reasons
for
choosing
the
use
of
ref
lected
light
mea
surement
:
a,
To
determ
ine the
brightness
ra
nge
of
a su
bject.
4.
b. To
photograph
illuminated
subjects
such as
neon
sign s.
c.
To
photograph
subjects when
you
are unable
to
measure
the incident light
(Figures
in
show
win-
dows,
etc.).
To
determine
the
brightness range,
install
the Lumi-
grid
and
direct it
about
6 inches
from
various
areas
of the
subject.
Be
careful
that neither
you
nor
the
meter
cast
a shadow
on
the area
being
read
,
(a
6"
diameter
circle).
Note the various indications
on
the
foot-candle
scale,
which
is
a convenient scale
for
determ
in ing
ra
nge.
Novr
divide
the highest
foot
candle
reading
by the
lowest
to
obtain
the
brightness range
of the subject.
For
exa mple
if
the
brightest area
reads
64,
a
nd the
lowest
4,
then
:
Range
_
tol
To determine
the
range limits for
good
color
photo-
graphs,
follow these rules:
(a)
None
of the objects
in
a scene
should be
more
than
four times brighter
or four
times
darker
than the mid-point
of the
brightness
range.
ln
other words
the
foot
ca
ndle
ra
nge
should
not
64
.?
4-ro
3.
32
5.
33