Canon EOS Rebel T4i 18-135mm IS STM Lens Kit Instruction Manual page 324

Troubleshooting Guide
Even though I set a decreased exposure compensation,
the image comes out bright.
Set [z2: Auto Lighting Optimizer] to [Disable]. When [Standard/
Low/High] is set, even if you set a decreased exposure compensation
or flash exposure compensation, the image may come out bright
(p.123).
When I use the <f> mode with flash, the shutter speed
becomes slow.
If you shoot at night when the background is dark, the shutter speed
becomes slow automatically (slow-sync shooting) so that both the
subject and background are properly exposed. To prevent a slow
shutter speed, under [z1: Flash control], set [Flash sync. speed in
Av mode] to [1/200-1/60 sec. auto] or [1/200 sec. (fixed)] (p.215).
The built-in flash is raised by itself.
In the A, 2, 4, and 6 modes, the built-in flash will be raised
automatically when flash is 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.306).
Under [z1: 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.216).
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