Pentax K20D User Manual page 92

Using the L (Shutter & Aperture Priority) Mode
You can set both the desired shutter speed and aperture to take the
picture.
Automatically sets the sensitivity so that the manually set shutter speed
and aperture will give the proper exposure according to the brightness of
the subject.
1
Set the mode dial to L.
2
Turn the front e-dial and adjust
the shutter speed.
3
Turn the rear e-dial and adjust
the aperture value.
The shutter speed, aperture value and
sensitivity are displayed in the
viewfinder and on the LCD panel.
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