Canon EOS 90D DSLR Camera with 18-135mm Lens - Manual (Page 267)

267
AF-Assist Beam Settings
You can specify to use the AF-assist beam of the built-in fl ash or a Speedlite
in viewfi nder shooting.
1 Select [ z : AF-assist beam fi ring].
2 Select an item.
 [ON] Enable
Enables fi ring of the AF-assist beam, when needed.
Press the <
D
> button to fi re the AF-assist beam from the built-in fl ash.
 [OFF] Disable
Disables fi ring of the AF-assist beam. Set if you prefer not to fi re the
AF-assist beam.
 [
1
] Enable external fl ash only
Enables fi ring of the AF-assist beam when needed, only when external
Speedlites are used.
 [IR] IR AF assist beam only
Enables infrared AF-assist beam fi ring by external Speedlites equipped
with this feature, when these fl ash units are attached.