Canon SPEEDLITE EL-10 Advanced User's Manual page 140

C.Fn-19:
You can select whether to update, based on ETTL flash output, the flash output maintained
in manual mode.
0: OFF
1: ON
2: ON /
Note
C.Fn-19 is set to [2], modes other than <
when pressing the <
different mode, press <
select an option, and select a mode.
If C.Fn-19: (FE memory) is changed or clear all is selected on the camera menu
[ : External Speedlite control], check whether the camera being used supports
C.Fn-19: (FE memory).
C.Fn-21:
You can change the Speedlite's light distribution (flash coverage) characteristics relative to
the shooting angle of view when flash coverage is set to <
0: (Standard)
Optimal flash coverage for the shooting angle of view is set automatically.
1: (Guide number priority)
Effective when prioritizing flash output, although image edges are slightly darker than
when set to [0]. Flash coverage is automatically set slightly more toward the telephoto
end than the actual shooting angle of view. The display changes to <
2: (Light distribution priority)
Effective when minimizing vignetting, although the flash range is slightly shorter than
when set to [0]. Flash coverage is automatically set slightly more toward the wide-angle
end than the actual shooting angle of view. The display changes to <
(FE memory)
> button on the <
> to display the setting screen, turn the <
(Light distribution)
> and <
> cross keys. To select a
> (Auto).
140
> cannot be selected
> dial to
>.
>.