Canon EOS Rebel T4i 18-135mm IS STM Lens Kit Instruction Manual page 163

x Shooting with the Touch Shutter
Even if <i> (continuous shooting) is set, single shooting will take
effect.
The touch shutter does not function when the view is magnified.
When [6: Shutter/AE lock button] is set to [1: AE lock/AF] or [3: AE/
AF, no AE lock] under [54: Custom Functions (C.Fn)], autofocusing
does not take effect.
You can also enable the touch shutter by setting [Touch Shutter:
Enable] in the [A] tab.
To take a bulb exposure, tap the screen twice. The first tap on the screen
will start the bulb exposure. Tapping it again will stop the exposure. Be
careful not to shake the camera when tapping the screen.
163