Film
choice
Using film with a speed of ASAIISO 400 or higher will
allow
you to use faster shutter speeds, thereby mini-
mizing the effects of camera movement
as
much
as
possible.
When
to
use
a speedlight
1)
To
restore natural colors to the subject
When
shooting color
fi
lm
without a speedlight, your
photos
will come out bluish because of the selective
filtration and light absorption of water.
Us
ing
a speed-
light will allow
you to capture the subject
in
all its
splendor.
2)
To
add illumination to the subject
When
shooting a subject that
is
partially in darkness
(such
as
the inside of
an
underwater cave or a face
behind a diver's mask), use a
speedlight to provide
more
illumination.
Underwater
photography
and
speedlight
guide
numbers
Because of the light absorption of water, the guide
number of a speed
light
is
lower underwater than
it
is
on
land. Also, because the transparency of the water
varies from situation
to
situation,
it
is
difficult to
calculate the aperture setting from the guide number.
As
a rule of thumb, use the following formula to calcu-
late
the aperture from the guide number when using
a
speedlight
in
fairly transparent water.
(1/2 to 1/3)Guide Number
Flash-to-subject Distance
f/stop
Poor vis
ib
il
ity may reduce the maximum shooting
distance and guide number even further.
For
best
results, take the first shot at the recommended expo-
sure, then take two additional shots with the lens at
the next two
numerically smaller f-numbers.
To
compensate for light loss
in
the A mode, use the
Sensor Unit
SU-101
when using the
SB-101
in
the
automatic mode.
Even
though the maximum shooting
distance will
be
cut
in
half, you will still obtain the
correct exposure. When shooting
manually, divide the
speedlight guide number by two.
In
the
TTL
mode, the
SB-103 or SB-102 automatically provides the correct
flash exposure.
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