Automatic diaphragm control, Manual diaphragm control – Canon A-1 User Manual
Page 142
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Automatic Diaphragm Control
When the A-1 is directly coupled with an FD
lens, diaphragm control is totally automatic.
Exposure metering is performed at full
aperture whether the lens aperture ring is at
the “A” mark or set to a specific aperture.
At shutter release, the diaphragm automati
cally closes down to the aperture set by the
camera or by you with the AT dial or the
aperture ring. Following shutter release, the
lens automatically returns to maximum aper
ture.
Manual Diaphragm Control
The insertion of manual accessories or a
macrophoto
coupler
between
the
camera
and an FD lens requires setting the lens for
manual diaphragm control before stopped-
down metering is possible. The instructions
for the various accessories involved will tell
you whether or not this is necessary.
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