Canon EOS 100D Basic Instruction Manual page 452

Troubleshooting Guide
The built-in flash is raised by itself.
In shooting modes (<A> <C> <2> <4> <C> <6>) whose
default setting is <
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 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.312).
Under [z2: Flash control] and [External flash C.Fn setting], if
[Flash metering mode] is set to [TTL], the flash will always fire at full
output (p.233).
I cannot set flash exposure compensation when
using an 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.232).
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.
336
> (Auto flash), the built-in flash will rise
a