Do yourself a huge favor.... Buy an accessory flash!
Built-in flashes are...
- Underpowered and weak.
- In the worst possible place for problems with redeye and ugly shadow effects.
- A heavy draw on the camera's battery.
- Slow to recycle.
An accessory flash is much better in all respects. They are a lot more powerful giving greater reach. They can be positioned off-camera on a bracket that moves them higher up and off to the side, to reduce redeye and shadow issues (an off-camera shoe cord is used to connect the flash to the camera). And they have their own power supply that makes them much faster recycling. Depending upon the model, they also can have a lot more user control and work better in multi-flash groups.
For example, your 80D's built-in flash has a 12 meter guide number and coverage for the equivalent of 28mm wide lens on full frame (17.5mm on your APS-C camera). A Canon 430EX III-RT flash has a 43 meter guide number and a diffusion panel that allows it to be used with as wide as 14mm lens on full frame (8.75mm on APS-C). Without the diffusion panel it covers 24mm on FF (15mm on APS-C). Further, the 430EX III-RT's head can be redirected upward or rotated to bounce off a ceiling, wall or reflector or umbrella for much nicer lighting results than is typically possible with direct flash. Built-ins can only be used as direct flash.
Canon's "RT" flashes and accessories use radio communications for wireless remote flash setups... one or more units. Many other EX flash units that aren't RT can communicate wirelessly using near infrared light, which isn't as versatile or far reaching as the radio system, but still offers a lot of versatility.
In fact, your camera may be set up so that the on-board flash is trying to communicate with off-camera flashes, without itself being set to fire. I don't have an 80D, but know this is possible with some of the cameras that have built-in flashes. It's also possible that the flash is set to only provide "focus assist". You might check your flash settings in the menu (see the user manual for help finding them).
But you still might want to consider an accessory flash, even if you get the built-in flash working again. I discovered that the built-in flash on one of my cameras was stuck.... about eight years after I bought it. That tells you about how often I use the built-ins!
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), EOS M5, some other cameras, various lenses & accessories
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