Canon EOS 5DS Instruction Manual page 422

83: Custom ControlsN
: AE lock (while button pressed)
The exposure will be locked (AE lock) while you press the shutter
button.
: AE lock (hold)
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. Convenient 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.
: AE lock, AF stop
When you press the button assigned to this function, you can lock the
exposure (AE lock) and the AF will stop. Convenient during AI Servo AF
if you want AE lock at the same time when AF stops.
: FE lock
During flash photography, pressing the button assigned to this function
will fire a preflash and record the required flash output (FE lock).
: Set ISO speed (hold button, turn
You can set the ISO speed by holding down <0> and turning the
<6> dial.
If this control is used while Auto ISO is set, manual ISO speed setting
will take effect. Auto ISO cannot be set. If you use this function in the
<a> mode, you can adjust the exposure with the ISO speed while
maintaining the current shutter speed and aperture.
: Set ISO speed (
During metering, you can set the ISO speed by turning the <5> dial.
The settable range is the same as with
If you assign [AE lock (while button pressed)] to the shutter button, any
buttons assigned to [AE lock] or [AE lock (hold)] will also work as [AE lock
(while button pressed)].
422
during metering)
)
.