Deterministic flash

Flash phenomena may seem stochastic, but they are deterministic. Look those words up if you like; what I mean is that whatever happens, it’s predictable, not random. When something goes wrong, look for, and find, the reason. If it seems weird, you just haven’t found the reason.

Yesterday, I ran into three curious flash phenomena in one day.  And just for fun, I’ll run them by you. So you’ll learn to solve these things by yourself.

*** 1. THE CASE OF THE MISSING TTL. You turn on your Canon 580EX flash, and instead of the MODE button toggling it between “ETTL” and “M”, it toggles between “e” and “M”. What gives?

Solution: you set something weird in the custom settings, and TTL has been disabled. Solution: set the custom settings back to default. Use a connected camera to do this, or read the manual for instructions for doing it manually.

*** 2. THE MYSTERY OF THE FIVE EXTRA STOPS. This is a common one. We set up everything properly, but the photo looks like this, at least five stops overexposed:

Solution: this is due to the flash firing at full power, instead of at the correct  lower power as calculated by TTL. The reason for this is almost always the same: a bad contact. For the TTL mechanism to work properly, all five contacts need to be good. And millivolts are easily lost if a contact is dirty, say. So sure enough, after cleaning the contacts, all went well:

*** 3. THE CONUNDRUM OF THE “A” THAT SHOULD BE AN “E”. The flash toggles between M and TTL, but instead of the usual “ETTL”, I see “ATTL”. ATTL was an earlier iteration of Canon’s TTL mechanism, while ETTL is the most recent version. Mysterious!

Solution: Here too, the reason was a bad contact. The phenomena that can result from bad contacts are legion. Cleaning the contacts worked: now I got normal ETTL again.

In my years as a photographer, I have seen many things go wrong with speedlites. I have found that although many things can be the cause of the malfunction, it’s usually settings or contacts. Check those before you do much else.


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