Canon EOS Rebel T3 18-55mm IS II Kit Instruction Manual page 222

3 Custom Function SettingsN
C.Fn-8
You can assign a frequently-used function to <0>. Press <0> when the
camera is ready to shoot.
0: Normal (disabled)
1: Image quality
Press <0> to display the image-recording quality setting screen on the
LCD monitor.
Select the desired image-recording quality, then press <0>.
2: Flash exposure compensation
When you press <0>, the flash exposure compensation setting screen
will appear. Set the flash exposure compensation, then press <0>.
3: LCD monitor On/Off
Assigns the same function as the <B> button.
4: Menu display
Press <0> to display the menu screen.
5: Depth-of-field preview
The lens will stop down to the aperture that was set, and you can see
the depth of field (range of acceptable focus) in the viewfinder or in the
Live View image.
C.Fn-9
0: Raise built-in flash
1: ISO speed
The ISO speed setting screen will appear. Press the <U> key or turn
the <6> dial to change the ISO speed. You can also refer to the
viewfinder to set the ISO speed.
222
Assign SET button
Flash button function