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"MFULL,"
"M1/4,"
and "M1/16"-Manual Flash
Modes
These modes can be used with the
Nikonos-V,
Nikonos
IV-A,
and Nikonos III. Manual control is very convenient
when the correct exposure cannot be obtained through
TTL automatic operation
.
The SB-103 has three manual
control modes for selection according to the flash-to-
subject distance and the shooting
situation.
The guide
numbers are GN 20 (10) at
the
" MFULL"
position
,
GN
10 (5) at
" M1/4,"
and GN 5 (2 .5) at
"
M1/16
"
when using
ASAIISO 100 film
.
(The guide numbers in
parentheses
are for underwater
photography).
To determine the
cor-
rect aperture
,
use the exposure calculation chart or
perform the calculations by yourself (see page
19).
TTL
Automctic Flcsh Control
In TTL automatic
flash
photography,
the useable aper-
tures are from f/2.8 to f/22 (when using ASAIISO
100
film), although the actual range for a specific shooting
situation depends upon the flash-to-subject distance,
the
ASAIISO
film speed, the type of
photography
(on-
land or
underwater),
and whether or not the wide-flash
adapter is being used
.
The actual ranges for specific situations can be easily
determined with the exposure calculation chart.
Exposure \,,;CIICLIlCTlon
In flash
photography,
which apertures can be used is
closely related to the flash-to-subject distance. To de-
termine the useable apertures
,
use the exposure
calcu-
lation chart.
Example 1:
When
shooting on
land
at f/4 without the wide-flash
adapter while using ASA/ISO 100 film
,
you can take
pictures
of subjects located between 0.9m (3ft) and
5m
(16.4ft).
In the same
manner,
when shooting underwater at f/11
with the wide-flash adapter while using ASAIISO 400
film
,
you can shoot subjects located between
0.3
m (1 ft)
and 1.2m (4 .3ft).
Before you
select an
aperture,
always take the flash-to-
subject distance into consideration
.
To
increase the
flash-to-subject
coupling
distance
as much as
possible,
select a larger flstop (a
numerically
smaller
f-number).
In
the opposite case, close-up shooting
,
select a smaller
flstop
(a numerically larger f-number).
17
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