Canon EOS 1300D - Manual (Page 260)

260
Custom Functions are organized into four groups based on the function
type: C.Fn I: Exposure, C.Fn II: Image, C.Fn III: Autofocus/Drive, C.Fn
IV: Operation/Others.
3
Custom Function SettingsN
C.Fn I: Exposure
C.Fn-1 Exposure level increments
0: 1/3-stop
1: 1/2-stop
Sets 1/2-stop increments for the shutter speed, aperture, exposure
compensation, AEB, flash exposure compensation, etc. This is
effective when you prefer to control the exposure in less fine
increments than 1/3-stop increments.
C.Fn-2 ISO expansion
0: Off
1: On
When you set the ISO speed, you will be able to set “H”
(equivalent to ISO 12800). Note that if [C.Fn-6: Highlight tone
priority] is set to [1: Enable], “H” cannot be set.
When 1 is set, the exposure level will be displayed in the viewfinder and on
the LCD Monitor as shown below.