3Setting the FlashN 
The built-in flash and external Speedlite settings can be set with the camera’s menu. You can use those menu options for the external Speedlite only if the attached EX-series Speedlite are compatible with them.
The setting procedure is the same as setting a camera menu function.
Select [Flash control].
Under the [1] tab, select [Flash control], then press <0>.
XThe flash control screen will appear.
[Flash firing]
Normally, set this to [Enable].
If [Disable] is set, both the built-in flash and external Speedlite will not fire. This is useful when you only want to use the flash’s AF-assist beam.
[Built-in flash func. setting] and [External flash func. setting]
The [Built-in flash func. setting] and [External flash func. setting] menus can set the functions listed on the next page. The functions displayed under [External flash func. setting] will vary depending on the Speedlite model.
Select [Built-in flash func. setting] or [External flash func. setting].
XThe flash functions will be displayed. The functions not dimmed can be selected and set.