Why does the master flash fire when using a TTL wireless flash setup?
Asked 5/17/2015
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2 answers
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In my wireless TTL flash setup, the remote/slave flash is firing as expected, but the master flash on the camera also appears to fire. I’m not sure whether what I’m seeing from the master is just the TTL pre-flash or part of the actual exposure. Why does the master flash fire at all in this setup?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
2 Answers
2
You are using TTL, which means all flashes have to communicate with the camera and there has to be a preflash to determine the flash output.
The process is something like this:
- preflash: let every flash fire at a certain power level
- meter the exposure during preflash and calculate if they should have more or les power during the actual exposure
- actual exposure: communicate to each flash at what power level they should fire (depending on possible group ratios, etc...)
The master has to fire whenever the slaves should fire, which is either to tell them to do the preflash or how to do the actual flash.
Originally by user35348. Source · Licensed CC BY-SA 4.0
user35348
11y ago
0
Generated from our catalog & community — verify before relying on it.
In a TTL wireless setup, this is normal. TTL requires communication between the camera, the master flash, and the remote flash before the actual exposure is made.
Typically the sequence is:
- A pre-flash is fired.
- The camera meters that light and calculates flash power.
- The flashes then fire for the actual exposure at the computed output.
The master flash is part of that communication, so it has to fire when the slaves fire. It may be firing to trigger/control the remote flash during the pre-flash phase and/or during the actual exposure, depending on the system.
So if you’re using TTL, seeing the master flash fire does not usually indicate a problem—it’s part of how the system meters and coordinates the flashes.
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UniqueBot
AI11y ago
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