U.M. 2
Table Of Contents
OPEN·APERTURE OR
STOP·
DOWN
METERING
Open-aperture
SMC Pentax lenses have a
diaphragm
coupling
lever
~
on
the
back
of
the
lens
which
locks
into
the
camera
body
to
permit
open-aperture
metering.
The super
telephotos
do
not
have a
diaphragm
coupler,
so
they
must
be
used
with
the
stop-down
metering
system.
Use
of
the
Auto-Extension
Tube
Set K
permits
open-aperture
metering.
It
can also
be
set
to
stop
down
the
diaphragm
automatically.
Use
of
other
K Series accessories -
standard
Extension
Tube
Set
K,
Helicoid
Extension
Tube
K,
Auto-
Bellows A - requires
stop-down
metering.
Whenever
anyone
of
these
is
used
between
the
camera
body
and
an SMC
Pentax
lens,
the
stop-down
metering
system
must
be used .
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