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EVRANGEOFCAMERA---------------------
The
camera's meter may
be
used only within the shutter speed
range covered by the exposure value (EV) range of the meter,
which varies with the aperture and ASAIISO setting.
The
charts
on
pages 68 and 69 show the relationships between
the f/stop, shutter speed and film speed, indicating the usable
functioning shutter speed (for metering purposes) with any film
speed/aperture combination.
Careful attention to the following instructions will assure precise
exposure, automatically, over the complete exposure control
and meter range capabilities of your Nikon F3
AF
.
WhatlsEV?
Exposure value (EV)
is
a number representing the available
combinations of shutter speed and aperture that give the
sa
me
exposure effect when the scene brightness and ASAIISO re-
main the same.
At
ASAIISO
100
, the combination of a one-second shutter
speed and
an
aperture of f/1.4
is
defined
as
EV
1. If the aperture
is
stopped down by one full f/stop or the shutter speed is one
step faster, the
EV
increases by one ; if the aperture
is
opened
up
by one full f/stop or the shutter speed
is
one step slower,
EV
decrea
ses
by one. Using ASAIISO
100
as
an
example, 1 sec. at
f/2 represents
EV
2, 1 sec. at f/5.6 represents
EV
5, while 1/
125
sec. at
1/5
.6 represents
EV
12
. Becau
se
the exposure
is
the
sa
me
, 1/30 sec. at
f/11
and 1/1000 sec. at f/2 both represent
EV
12
.
66
How
to
Read
the
EV
Chart
Section A of the chart shows the usable
EV
range depending
on
the lens' maximum aperture
in
full-aperture metering, while
it
also indicates the usable
EV
range for aperture settings
in
stop-down metering. Section D shows
the
value for the ASAIISO
film speed, Section B the aperture settings for various film
speeds, and Section C the shutter speeds to match any film
speed/aperture combination.
In
practice,
you
will find that
it
is
generally the high end and the
low end of the metering range which require a careful check.
The
EV
range of the Nikon F3AF encompasses most lighting
situations, and it
is
only under very dim or very bright picture-
taking situations that you need pay any special attention.
Full-aperture metering
Use
the Nikkor 50mm f/1.4 lens and a film speed of ASAIISO
100
as
an
example.
By
referring to the f /1.4 column
in
Section A
and the
EV
value indicated for ASAIISO
100
in
Section
D,
you
will find that the F3AF's
EV
range
in
this case
is
1 to
18
.
If
the lens
is
set at f/5.6, refer to Section B
and
single out the
f/5.6 indication for ASA/ISO
100
.
Go
diagonally down until the
protruding line intersects with Section C's vertical line for a
shutter speed of 8 sec. (the F3AF's slowest shutter speed).
From this point of intersection, follow
the
horizontal line that
leads to the Section D
's
EV
value for ASAIISO
100
, and
you
will obtain
an
EV
range of 2. Start again from the f/5.6 indication