Canon A-1 - Manual (Page 152)

Exposure warnings are very similar to those
in shutter-speed priority AE. If you have set
an auto working aperture larger than the
maximum aperture of the lens, the maxi­
mum aperture of the lens will flash on and
off to indicate underexposure. If you have
set an auto working aperture smaller than
f/16, the set auto working aperture will flash
on and off. If the minimum aperture of the
lens is equal to or smaller than the flashing
aperture, exposure will be correct. If larger,
the image will be overexposed.
If, with Speedlite 199A, you want to use a
shutter speed of 1/30 sec. or slower, set the
AE mode selector to Tv and the AT dial to
the desired shutter speed and set the shutter
speed selector switch on the 199A to the
MANU position. In this case, the shutter
speed on the AT dial will be displayed in
the readout.
B D
F B . B
2. Automatic Flash Control with Canon
Speedlite 133A, 155A, 177A or 199A
The flash is on Auto but the aperture is
manually set by turning the lens aperture
ring. This type of automatic flash control is
necessary with an FL lens and other non-FD
lenses and possible with an FD lens when it
is not set to “A”.
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