Canon 577 G - Manual (Page 16)

SETTING AN APERTURE
ON THE FLASH
You set an aperture with the aperture
selection switch on the back of the
577G. The switch has three color-
coded positions: red, green and yel­
low. As you slide the switch, the color
of the position you have set will
appear in one of three windows on
the back of the flash.
a) Auto Shooting Distance Ranges
b) Auto Aperture Indices
c) Selection Switch Position
Indicators
Each position has a corresponding
aperture and auto shooting distance
range. The auto aperture is the f-
number which is directly opposite
the dot which is the same color as
the position of the aperture selection
switch. It changes with the ASA film
speed you have set on the calculator
dial. For instance, if you have set the
aperture selection switch to the red
position, the auto aperture will be
f/2.8 at ASA 100 but f/5.6 at ASA 400.
The auto shooting distance range is
indicated by the straight white line
which is directly opposite the set­
ting of the aperture selection switch.
There are three lines, one for each
position of the switch. Each repre­
sents the range of distances from the
subject for which that position of the
selection switch will give correct ex­
posure. If the camera is out of that
range, the subject will be over- or
underexposed. There are two ways
to check that the camera is within
that range: either by reading the
lens’ distance scale after focusing
or by the auto check lamp (see p. 16).
When you are deciding which of the
three positions of the selection
switch you should set, place prime
importance on the shooting distance
range. If the actual shooting distance
falls within the range of two or all
three positions, take depth of field
into account.
* The indicated auto shooting dis­
tance ranges only hold true if the
flash is pointing straight at the
subject. If the flash head is tilted
or swung for bounce flash, or if
the flash is held some distance
from the camera, rely on the auto
check lamp to tell you if you are
within the correct range (see p.
26). These ranges also change if
a wide or tele adapter is at­
tached. See p. 23 and “Specifi­
cations”, p. 35.
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