Lens aperture scale – Canon IV-S2 User Manual
Page 13
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Lens Aperture Scale
The Lens Aperture controls the amount of light entering
the
lens
and
also
the
Depth
of
Field.
Set
ih«
Letrs
Aperture
(f-stop)
by
turning
the
Aperture
Scale
i.knurled
ring)
to
the
proper
position.
This
is
best
determined
with
an
exposure
meter
or
by
following
the
instructions
given with the film.
When
the
Lens
Aperture
is
closed
by
one
stop;
the
amount of light entering the Lens is decreased by one
half,
two
stops,
by
one
quarter
and
so
on.
Therefore
you
should
adjust
the
Lens
Aperture
in
conjunction
with
your
shutter
speed.
Suppose
your
exposure
meter
indicates a speed of 1/200 sec. at f : 5.6. If you want
to expose for a slower speed say 1/100 sec., then you
must close down the Lens Aperture to f ; 8. In other
words,
as
you
have
doubled
the
time
of
the
shutter
opening,
you
must
reduce
the
amount
of
light
entering
the lens by half to obtain the correct exposure.
Knurled Ring