For example, if you're using DIN 15 (ASA 25) film and
yo
ur flash-t
o-
subject distance is 2% meters (7%
fe
et), the 283's Calculator
Dial
indicates correct exposure at
f8
. If you now set the Varipower
Dial
at
"2"
or % power, your photograph wi
ll
be
unde
re
xposed
1-stop unless
yo
u open your lens diaphragm to the next larger f-stop.
In
this exampl
e,
the exposure correction indicate
s"
- 1" which
would result
in
correct exposure
at
f5
.
6.
Since the
VP-1
provides continuously variable control, you may
visually estimate exposure corrections
in
V3
or
V2
f-stop
in
crements
when the Varipower
Dial is set with the Varipower Index Mark
between marked positions.
NOTE: The minimum Varipower Dial
se
tting is marked with a dot ( . )
at
which point
th
e
VP-1
will limit
li
ght output to approximately 6
f-stops
below exposure at full manual power. A few test exposures
will quic
kl
y establi
sh
the exact exposure correction for
yo
ur
283 using this minimum
dial setting.
Balancing "fill-in" lighting -
You
may dial to a specific exposure correction when using you r
283
as
a
"fill-in"
light. For exampl
e,
u
si
ng
DIN 15 (ASA 25) film,
5
your daylight exposure calc
ul
ations call for
f8
at
1/60
second.
(Remember
to
check your camera's shutter speed requirements for
"X"
synchronization.) If your flash-to-subject distance
is
2% meters
(7% f
ee
t
),
proper flash exposure would also be
f8
. Taking the
picture with these daylight and
fl
ash conditions wou ld produce a
st
rong fill (the
fl
ash " fill " illumination equals
th
e daylight illumination
used
as
a
"mai
n"
li
ght). For a normal fill, you would ordinarily
increase flash-to-subject distance to 3.3 meters
(11
feet). For a
weak
fill, you would increase
fl
ash-to-subject distance to 4.6 meters
(
15
feet) . However, you may not have room to make
th
ese increases
in
fla
sh
-to-subject distance. Also, if your flash is mounted on
you r camer
a,
you'll
al
ter the composition of you r picture if you begin
moving camera and
flash to increase flash-to-subject distances.
With the Vivitar
VP-1
Varipower Module, simply dial to " - 1" for
normal
fill, or dial to " -
2"
for a weak fill. There's no need to
change the flash-ta-subject distance.
Conserving battery power and shortening recycle time -
Th
e Vivitar
VP-1
Varipower Module utilizes your 283's
Th
y
ri
stor
Circuitry to co
nt
rol light outpu
t,
in much the same manner that its
Automatic
Flash Circuitry
tu
rns off the light for preprogrammed
6
a
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