Canon EOS 70DN Basic Instruction Manual page 587

The built-in flash is raised by itself.
In shooting modes (<A><C><2><4><6>) whose default setting
is <a> (Auto flash), the built-in flash will rise automatically when
necessary.
The built-in flash does not fire.
If you shoot continuously with the built-in flash at short intervals, the
flash may stop operating to protect the flash unit.
The external flash does not fire.
If you use a non-Canon flash unit with Live View shooting, set [A2:
Silent LV shoot.] to [Disable] (p.231).
The external flash always fires at full output.
If you use a flash unit other than an EX-series Speedlite, the flash will
always be fired at full output (p.194).
When the external Speedlite's [Flash metering mode] Custom
Function is set to [TTL] (autoflash), the flash will always be fired at full
output (p.202).
Flash exposure compensation cannot be set for the external Speedlite.
If flash exposure compensation has already been set with the external
Speedlite, flash exposure compensation cannot be set with the
camera. When the external Speedlite's flash exposure compensation
is canceled (set to 0), flash exposure compensation can be set with
the camera.
High-speed sync cannot be set in the <f> mode.
Under [z2: Flash control], set [Flash sync. speed in Av mode] to
[Auto] (p.196).
The camera makes a noise when it is shaken.
The built-in flash's pop-up mechanism moves slightly. This is normal
and not a malfunction.
Troubleshooting Guide
423