Canon A-1 Instructions Manual page 84

Of course, with the flash still on Auto
you can set the aperture manually should
you wish to use an FL lens. Even then,
however, the camera will automatically
switch to 1/60 sec. as soon as the Speedlite
is ready for firing.
These Speedlites employ a unique light
sensing system, separate in the case of the
577G and 533G, which reduces excessive
reflection from the central area to give
better overall exposure.
With the Speedlites 577G, 533G and 199A,
shutter speeds slower than 1/60 sec. can be
selected resulting in a lighter background.
To control depth of field , you can choose
among three working aperture that are
automatically preset by the camera. The
577G, 533G and 199A also allow bounce
flash. With their corresponding wide angle
adapter, flash coverage of a 24mm lens
field with the l 99A and of a 20mm lens
field with the 577G and 533G is possible.
A thyristor circuit assures continuous flash
shooting at close distances.
General Flash Photography
When you use the A-1 with flash units o ther
than the Speedlites 577G, 533G I 99A,
188A, l 77A, 155A and 133A,
set
the AE
mode selector to Tv and the shutter speed
to 1/60 sec. or slower. With this setting on
the camera, other types of electronic falsh
units can be synchronized with your A-1.
either thro ugh the hot shoe or via the PC
socket on the front of the camera body.
These allow two separate falsh units to be
fired simultaneously.
Aperture should be manually set on the
aperture ring to the working apertures speci-
fied for an automatic electronic flash or be
determined through a guide number calcu-
lation using the following formula .
Guide Number
Aperture =
Shooting Distance
When doing the math, make sure that the
guide number and shooting distance are both
in the same unit, whether melers or feet.
The fastest shutter speed for use with
electronic flash is 1/ 60 sec., for use with M
or FP bulbs , 1/30
sec.
It is reco mmended to use a Canon flash unit
on this camera. Using a flash or flash acces-
_84 _
s01y of ano ther make may cause the camera