Pentax 645 645 Manual - Page 50

Flash, Operation

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TTL AUTO FLASH OPERATION TTL auto flash unit As illustrated, the light entering through the taking lens strikes the film plane; a separate exclusive photo sensor registers the light reflected off the film plane and flash luminosity thereby is automaically controlled. Since only the light reflected from the subject is used for measuring purposes, an accurate exposure is obtained. All available f/stops on the lens may be also used for TTL auto flash control although there are some limitations regarding the flash-to-subject distance for each preset f/stop. Completion of flash charging automatically adjusts the shutter speed to the flash synchronization speed of 1 /60 sec. The .x marking will appear in both windows to signify the completion of flash charging. r- r Aperture set to respective f/stops [either in Aperture-priority AE or Metered manual mode] • Set the aperture ring to desired f/stop. • Simultaneously with the completion of TTL auto flash charging, the viewfinder LED will indicate the flash synchronization speed of 1/60 sec. Aperture set to "A", [either in Programmed AE, Aperture-priority AE or Shutter-priority AE] . • Upon completion of the flash charging process of the TTL auto flash, the viewfinder LED display will indicate the flash synchronization speed of 1/60 sec. and the aperture of f/4 with ISO 100 film (f/8 with the AF080C ring flash). With a film of a different speed, the f/stop will automatically change. However, the maximum flash-to-subject distance will remain unchanged. Refer to the operating manual of your flash unit. The standard 75mm f/2.8 lens is the only one that can be used with the AF080C Ring Light. (Use the 58 49mm Adapter Ring to fit the flash on the lens.) 48

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TTL
AUTO
FLASH
OPERATION
TTL
auto
flash
unit
As
illustrated,
the
light
entering
through
the
taking
lens
strikes
the
film
plane;
a
separate
exclusive
photo
sensor
registers
the
light
reflected
off
the
film
plane
and
flash
luminosity
thereby
is
automaically
controlled.
Since
only
the
light
reflected
from
the
subject
is
used
for
measuring
purposes,
an
accurate
exposure
is
obtained.
All
available
f/stops
on
the
lens
may
be
also
used
for
TTL
auto
flash
control
although
there
are
some
limitations
regarding
the
flash
-to
-subject
distance
for
each
preset
f/stop.
Completion
of
flash
charging
automatically
adjusts
the
shutter
speed
to
the
flash
synchronization
speed
of
1
/60
sec.
The
.x
marking
will
appear
in
both
windows
to
signify
the
completion
of
flash
charging.
r
-
r
Aperture
set
to
respective
f/stops
[either
in
Aperture
-priority
AE
or
Metered
manual
mode]
•
Set
the
aperture
ring
to
desired
f/stop.
•
Simultaneously
with
the
completion
of
TTL
auto
flash
charging,
the
viewfinder
LED
will
indicate
the
flash
synchronization
speed
of
1/60
sec.
Aperture
set
to
"A",
[either
in
Programmed
AE,
Aperture
-priority
AE
or
Shutter
-priority
AE]
.
•
Upon
completion
of
the
flash
charging
process
of
the
TTL
auto
flash,
the
viewfinder
LED
display
wi
ll
indicate
the
flash
synchronization
speed
of
1/60
sec.
and
the
aperture
of
f/4
with
ISO
100
fi
lm
(f/8
with
the
AF080C
ring
flash).
With
a
film
of
a
different
speed,
the
f/stop
will
automatically
change.
However,
the
maximum
flash
-to
-subject
distance
will
remain
unchanged.
Refer
to
the
operating
manual
of
your
flash
unit.
The
standard
75mm
f/2.8
lens
is
the
only
one
that
can
be
used
with
the
AF080C
Ring
Light.
(Use
the
58
49mm
Adapter
Ring
to
fit
the
flash
on
the
lens.)
48