Canon AE-1 - Manual (Page 91)

Manual Aperture Control
When accessories requiring manual
aperture control are used between the camera
body and a lens, lock the automatic aperture
lever in the manual position before mounting
the lens.
I
Lock for Manual Aperture Control (1)
For manual aperture control, push the
automatic aperture lever counterclockwise
until it stops and locks. When accessories such
as extension tubes are attached to a lens that
has been set for manual control, the dia­
phragm blades of the lens open or close as the
aperture ring is turned. To revert from manual
control, reset the automatic aperture lever in
its original position.
2 Lock for Manual Aperture Control (2)
There are some FD lenses with the
manual lock lever requiring a different pro­
cedure for manual control setting. With these
particular lenses, the automatic aperture lever
must be turned fully counterclockwise while
the manual lock lever is brought to the "L"
position. Once this has been done, when the