Canon EOS 80D - Manual (Page 245)

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Wireless Flash PhotographyN
*1: If the slave Speedlite does not have a transmission channel setting function,
the flash can work regardless of the camera’s channel setting.
*2: In small rooms, the slave unit may work even if its wireless sensor does not
face the camera. The camera’s wireless signals can bounce off the walls and
be received by the slave unit. When using an EX-series Speedlite with fixed
light-emitting unit (flash head) and wireless sensor, take pictures while making
sure it can fire.
 Canceling the slave unit’s auto power off
To cancel the slave unit’s auto power off, press the camera’s
button. If you are using manual flash firing, press the slave unit’s test
firing button to cancel the auto power off.
The camera’s master function cannot be used for wireless flash photography
with radio transmission.