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•
Auto exposure control at full aperture
For
example,
with
an
f/1.4 lens and ASA 100 film,
the ELW's automatic shutter will function
down
to one second
with the lens
set at
1.4,
and
propor-
tionately slower as the aperture is closed.
Using
a standard of ASA 25 film, you
may be
assured of at least a four second speed regardless
of the aperture of the
lens used
as
long
as the
lens
is set at full aperture (refer to
Table).
Using
ASA 400
at
f/l.4, the slowest speed is
1/4
second;
however,
as the aperture is closed, the
functioning shutter speed
becomes progressively
slower until we reach f/5.6 when the slowest speed
of four seconds is functioning.
• Auto exposure
control
with stop-down meter-
ing
When using
a
bellows
or other extension equip-
ment, which disengages
the
meter
coupling
device,
it is
necessary
to revert to stop-down
metering.
Certain
limitations
are imposed
in
this
mode.
As
lens-to-film distance
is increased, the
metering
range (EV range)
changes proportionately. For
example,
when
an f/2
lens
is
used
at 2:1
reproduction (twice
life-size)
the effective f/num-
ber
is f/5.6.
When used
at f/8, the effective
f/number is f/22.
When pictures
are taken under
minimal
light
levels,
it
is desirable
to
use
a
high-speed
film (ASA
160
or
higher)
.
Using Tri-X
at film speed 400 with
stop-down
metering,
with an effective f/number of
f/8, the shutter speed range
would be
from
1/4
second to
1/1000.
Should
the
light level drop
below
EV6, it would
be
out of the shutter speed
range of the
meter.
Table
Slowest
shutter speed at full
aperture with any
lens
ASA
speed
Slowest
shutter speed
(sec.)
1600
1/15
800
1/8
400
1/4
200 (160)
1/2
100
(
80)
1
50
(
64)
2
25
4
37
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