Canon EOS REBEL T3 Basic Instruction Manual page 304

3 Custom Function SettingsN
With setting 2, the continuous shooting speed will be slower (with the
image-recording quality set to JPEG or 1+73). The maximum burst
during continuous shooting will also decrease (with the image-recording
quality set to JPEG or 1).
If you playback a 1 or 1+73 image with the camera or print an
image directly, the effect of the high ISO speed noise reduction may look
minimal. You can check the noise reduction effect or print noise-reduced
images with Digital Photo Professional (provided software, p 270).
C.Fn-5
0: Disable
1: Enable
Improves the highlight detail. The dynamic range is expanded from the
standard 18% gray to bright highlights. The gradation between the grays
and highlights becomes smoother.
With setting 1, the Auto Ligh ing Optimizer (p.107) is automa ically set to
[Disable] and the setting cannot be changed.
With setting 1, noise may become slightly more pronounced han with
setting 0.
With setting 1, the settable range will be ISO 200 - 6400.
Also, the <A> icon will be displayed on the LCD monitor and in the
viewfinder when highlight tone priority is enabled.
C.Fn III: Autofocus/Drive
C.Fn-6
The AF-assist beam can be emitted by the camera's built-in flash or by an
external, EOS-dedicated Speedlite.
0: Enable
If necessary, the AF-assist beam will be emitted by the built-in flash or
external Speedlite.
1: Disable
The AF-assist beam is not emitted.
220
Highlight tone priority
AF-assist beam firing