Pentax K1000 - How to Use Mount Adaptor K

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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