Pentax smc -FA Operating Manual page 22

65 28
80 80
A 22 16 11 8 5.6 3.5
Manual aperture
To set the aperture of the zoom lens manual-
ly, align the aperture-A index with the white-
bar index. The dot on the left-hand side of the
white-bar index serves as an index to align
an f-stop other than "A" when shooting at a
longer focal length.
For example, when using the FA Zoom 28-80
mm lens and wishing to set the aperture to f/8
with the focal length at 80 mm, align "8" on
the aperture ring with the dot on the left-hand
side.
20
80 80 65 28
A 2216 11 8 5.6 3.5
"A" (Auto) position
To set the aperture to "A" (Auto), align the
aperture-A index with the white-bar index,
regardless of focal length selected.