EXPOSUREVALUE(EV)----------------------
--------
Exposure consists of shutter control and aperture control.
The N4004s olfers a range of speeds from 1/2000 second to 1
second, with each setting twice as fast as the next slower speed.
Faster speeds allow less light to pass; slower speeds admit more
light.
Aperture control enables you to vary the lens aperture opening
from large to small, with larger apertures allowing more light to
pass, and sma
ll
er apertures allowing less light to pass.
Th
e standard aperture setti
ng
s are
fl.4
, f2, f2.
B,
f4,
f5.
6,
fB,
fll,
f16,
f22,
132,
etc.
For simplicity, shutter/apertu
re
gradations are uniform. A change
in
shutter speed from 1/125 to
11250
second, for example,
re
-
duces the light by 1/2. Similarly, changing aperture from f4 to
f5.6 reduces the light by 1/2. Each film used has a particular
sensitivity to light, indicated by the
ISO
number shown
on
the
film cartridge.
To
achieve
th~
correct exposure for any particular
light value, the camera's Image Master Control adjusts the
shutter speed and aperture control so just the right amount of
light reaches the film to produce the correct exposure. That
amount of light
is
referred to as the Exposure Value or
EV
and
is assigned a number such as EV10,
EV15,
etc. The brighter the
light, the higher the
EV
number.
52
Each
EV
number can
be
applied to a variety of shutter and
aperture combinations. If the correct exposure is
11125
f5.
6,
for
example, a setting of 1/250
f4
would produce the same exposure.
The same
EV
number would represent both settings.
The preceding explanation should help you understand the charts
found
in
different parts of this manual. But don't worry about the
details-the
Decision Master System of the N4004s takes care
of all calculations and automatically sets the exposure control.
Thi
s information is provided only for your reference and a fuller
understanding of photography.
