Minolta Flash meter IV User Guide

&posihte
mefers'ehd
film
Siensitivity
It is
important
to know
the characteristics
of
the
film when thinking
about
exposure.
When the
film is developed,
the amount
of
light
(exposure)*
on
the
film appears
as the
density
of
images on
the
film.
The line
graph
illustrating
the
relationship
between
expo-
sure
and density
is the
film characteristic
curve.
The characteristic
curve
indicates
film sensitivity,
which
is
required
when determining
exposure,
film
latitude
and other
:
factors
important to a obtaining
correct exposure.
"
-
Fig. A shows
the
typical
characteristic
curves
for color
reversal and
color
negative
films. As would
be expected,
these curves
indicate
opposite
tendencies
for
each
of
the three
primary
colors,
red:
green,
and
blue.
We will
refer to
the composite
curve of
Fig. B
to
simplify
the discussion
here.
The X-axis
indicates
the
logarithm
of the exposure,
and
the
Y-axis
is the transmission
density
of the
film. Color
reversal film
becomes
increasingly
transparent
as
the
expo-
sure
increases,
and becomes
increasingly
opaque
as
the exposure
decreases,
pro-
ducing
an
inverted
S-curve
descending
to the
right.
The curve
indicates that exposure
,
and
density
are
not
proportional
at the
two extremes
(the
top and
bottom of
the
curve)'
but
are
proportional
through
the
straight
line in between.
This straight
line indicates
that
part
of the
film
which
most accurately
reproduces
variations
in
light intensity
on
. .l
thesubject.
.'t.t:
,;,'-,
This range
is referred
to as
the
film's exposure
latitude,
most commonly
a
difference
of about
five
stops
between
maximum
and
minimum
exposures
with
color
reversal
,:.
film.
(The
area between
S and
H on the
Flash
Meter
IV
contrast
scale
is the exposure
:'
latitude of
the
film.)At
about
the center of
this
range is
reference
exposure
Hm,
which
is
used
to calculate
film
sensitivity;
the intersection
at which
reference
Hm
produces
midtone
density
Dm
is film sensitivity
M.
With
incident
light
metering,
the
required exposure
is
obtained
by
measuring
illumi'
nation on the
subject.
Exposure calculations
in this system
are designed
to
reproduce
an
18%
gray
subject
exposed
at the
indicated
aperture
and
shutter
speed
in neutral
:.:
tones,
i.e. at
mean densitY
Dm.
-,
In reflected-light
metering systems,
the
light reflected
by
the subject
is measured
to
..,,,
determine
subject
luminance,
and exposure
is adjusted
so
this is equivalent
to
refer-
'"
ence
exposure
Hm.
In
other
words, all
subjects,
no
matter
what their
reflection
factor,
will be
reproduced
as a
mean density
Dm
image. In
actual
photography,
the
highest
reflection
factor encountered
for white objects
is
about
85%
to 9Ao/o,
and the
lowest
reflection
factor
is that
of
black objects,
about
2.5o/o to
3%.
In terms
of exposure
differences,
this
range breaks
down
into
about
five
stoPs
of
apprOximately
3o/0,60/o,
120/o,24.0/0,
4Bo/0,
and
96%,
placing
the
18%
gray
subject
roughly
the
middle.
Accordingly,
the exposure
indicated
by an
incident
light
meter and
theixposure
indicated
by
a reilected
light
meter
using
a subject
with a
reflection
factor of approximately
18% will
be nearly
equal
under equivalent
lighting
conditions.
lf thepicture
is exposed
at
the
metered
levels, subjects
with
a
reflection
factor
of
from
l6
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Minolta Flash meter IV Specifications

General

Light Receptor	Silicon photo cell
ISO Range	ISO 3 to 8000
Shutter Speed Range	30 min to 1/8000 sec
Display	LCD
Type	Handheld Flash Meter
Measuring Modes	Ambient, Flash
Measuring Range (Ambient)	EV -2 to EV 19.9 (ISO 100)
Measuring Range (Flash)	f/1.0 to f/90.9