Why does my Canon DSLR recognize a third-party flash and limit it in Live View?
Asked 8/11/2017
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I have a genuine Canon MR-14EX Macro Lite and a cheaper third-party copy. Both work on my Canon EOS 650D, but the camera seems to recognize that the generic flash is not Canon and it will not fire properly in Live View mode. How does the camera detect that the flash is third-party? Is this done through the hot shoe contacts, and is there any practical workaround?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
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At a very generic level:
- There's a small microcontroller in the flash.
- The CPU in the camera talks to the microcontroller in the flash.
- If the camera gets the responses it's expecting, it treats it as a Canon flash and lets you do everything with it.
- If the camera doesn't get the responses it's expecting, it degrades the functionality.
Canon will claim this is to prevent third-party equipment from potentially damaging the camera. While this is maybe partially true, it also has the "convenient" side effect of meaning people need to buy Canon flashes...
As for exactly what the communication between the camera and the flash is, that's what the third party flash manufacturers would all like to know. It's proprietary to Canon and the only way other companies have discovered it is via reverse engineering.
(While the above may read like a rant against Canon, every other major manufacturer does the same. At least Sony are using a standard hotshoe these days, rather than a different physical connector they used a few years ago...)
Originally by user11371. Source · Licensed CC BY-SA 4.0
user11371
8y ago
0
Generated from our catalog & community — verify before relying on it.
Canon cameras and dedicated flashes communicate through the hot shoe’s extra contacts, not just the center firing pin. Inside the flash is a small controller, and the camera exchanges data with it to identify the flash and manage features like E-TTL and Live View behavior.
If the camera gets the responses it expects from a Canon-compatible flash, it enables full functionality. If the responses are missing or don’t match Canon’s protocol closely enough, the camera may fall back to reduced operation or disable some features, such as Live View flash use.
The exact communication protocol is proprietary to Canon. Third-party makers usually approximate it through reverse engineering, which is why compatibility can be incomplete even if basic firing works.
So yes: detection is via the hot shoe/interface communication. In practice, there usually isn’t a camera-side setting to force full compatibility. The realistic workaround is to use a flash with better Canon protocol support, use the Canon unit, or accept limited functionality with the third-party copy.
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