Canon EOS 80D - Manual (Page 487)

487
Troubleshooting Guide
 If you use the built-in flash too often in too short a period of time, the
flash may stop firing for a while to protect the light-emitting unit.
 If you use a non-Canon flash unit with Live View shooting, set [z6:
Silent LV shoot.] to [Disable] (p.272).
 If you use a flash unit other than an EX-series Speedlite, the flash will
always be fired at full output (p.234).
 When the external Speedlite’s [Flash metering mode] Custom
Function is set to [TTL] (autoflash), the flash will always be fired at full
output (p.243).
 If flash exposure compensation is set with the external Speedlite, flash
exposure compensation cannot be set with the camera. When the
external Speedlite’s flash exposure compensation is canceled (set to
0), flash exposure compensation can be set with the camera.
 Under [z1: Flash control], set [Flash sync. speed in Av mode] to
[Auto] (p.236).
The built-in flash does not fire.
The external flash does not fire.
The external flash always fires at full output.
Flash exposure compensation cannot be set
for the external Speedlite.
High-speed sync cannot be set in the <f> mode.