Canon SPEEDLITE EL-1 Advanced User's Manual page 205

C.Fn-21:
You can change the light distribution (flash coverage) characteristic of the flash relative to
the shooting angle when the flash coverage is set to <
0: (Standard)
The optimum flash coverage for the shooting angle of view is set automatically.
1: (Guide number priority)
Although the periphery of the picture is slightly darker than the 0 setting, this is effective
when you want to give priority to the flash output. The flash coverage is set
automatically to a slightly more telephoto position than the actual shooting angle of view.
The display changes to <
2: (Light distribution priority)
Although the possible flash photography distance becomes slightly shorter than the 0
setting, this is effective when you want to minimize light fall off at the periphery of the
picture. The flash coverage is set automatically to a slightly wider position than the
actual shooting angle of view. The display changes to <
C.Fn-22: (LCD panel illumination)
When a button or dial is operated, the LCD panel illuminates. You can change this
illumination setting.
0: 12 sec (illumination for 12 sec)
1: OFF (Disable panel illumination)
2: ON (Illumination always on)
C.Fn-23:
When the receiver unit is fully charged during wireless flash photography, the AF-assist
beam emitter of the receiver unit blinks. You can disable this blinking. Set this function for
each receiver unit.
0: = (AF-assist beam,
1: ( lamp)
(Light distribution)
>.
(Receiver charge confirmation)
lamp)
> (automatic setting).
>.
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