Pentax 6x7 Manual page 9

• MANUAL DIAPHRAGM LENSES - - - - - - - - - - -
it will lock on manual (MAN .). To re - engage
the automatic diaphragm , press on the lever
again and let go so that the lever returns to
the AUTO position .
MANUAL DIAPHRAGM LENSES
SMC TAKUMAR
SMC TAKUMAR
SMC TAKUMAR
400mm f / 4
600mm f / 4
800mm f / 4
67 lenses from 400mm through 800mm
telephoto (except 500mm f / 5.6) feature a
manual diaphragm which is stopped down by
rotating the aperture ring to the various
click-stop f -number settings. This method is
used with all long telephoto lenses, except
the 1000mm reflex telephoto which does not
employ a diaphragm . When using manual
diaphragm lenses, focus with the lens set at
maximum aperture, and then stop it down to
shooting aperture just before tripping the
shutter.
Preset Diaphragm
The SMC Penta x 75mm shift lens features
a preset diaphragm system, whereby the
shooting aperture is preset with a preset
ring , so focusing and composition are per-
formed at full-aperture . Then , the aperture
is stopped down for exposure metering and
shooting by turning the aperture ring until it
matches up with the preset ring , (Operating
details are given in the instruction manual
furnished with the lens.).