Canon EOS 80D - Manual (Page 437)

437
8 : Custom Controls
When you press the shutter button halfway, exposure metering is
performed (AF is not performed).
Normal shooting (No flash)
When you press the button assigned to this function, you can lock the
exposure (AE lock) during the metering. Useful when you want to focus
and meter the shot at different areas or when you want to take multiple
shots at the same exposure setting.
With flash
During flash photography, pressing the button assigned to this function
will fire a preflash and record the required flash output (FE lock).
When you press the button assigned to this function, you can lock the
exposure (AE lock) during the metering. Useful when you want to focus
and meter the shot separately.
The exposure will be locked (AE lock) while you press the shutter
button.
When you press the button assigned to this function, you can lock the
exposure (AE lock). The AE lock will be maintained until you press the
button again. Useful when you want to focus and meter the shot
separately or when you want to take multiple shots at the same
exposure setting.
q : Metering start
t : AE lock/FE lock
A : AE lock
A : AE lock (while button pressed)
T : AE lock (hold)