Why don't my studio strobes fire correctly when triggered by the Canon 77D built-in flash in wireless mode?

Asked 5/19/2018

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I'm trying to trigger studio strobes using the built-in flash on my Canon 77D. When I use the camera's wireless flash mode, the flashes seem to trigger, but there's no visible flash contribution in the final image. I also tried changing shutter speed, but it didn't help. Why does this happen, and what settings should I use instead?

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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The built-in flashes of modern cameras (as well as most hotshoe strobes) use a "pre-flash" to measure the scene. A small burst of light happens right before (or right as) the shutter opens, and that is evaluated to calculate the power for the full flash.

This works pretty well, but it also means that traditional secondary flashes that trigger when they notice a burst of light are fooled and can fire too soon. Some have a mode where they ignore the first burst for exactly this reason — check if your studio light does.

Originally by user1943. Source · Licensed CC BY-SA 4.0

user1943

8y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

Canon's built-in wireless flash mode sends multiple light pulses before the exposure to communicate with compatible Canon wireless flashes. Studio strobes usually use a simple optical slave, so they fire as soon as they see the first pulse. That means they can go off too early, before the shutter is actually open, so you don't see their light in the photo.

A similar problem can happen with E-TTL pre-flash metering: the optical slave reacts to the pre-flash instead of the main flash.

To fix it:

  • Don't use the 77D's wireless flash mode to trigger studio strobes.
  • Set the built-in flash to manual flash mode instead, so it emits a single normal flash pulse.
  • Use a low manual power setting if needed, just enough to trigger the strobes.
  • If your studio lights have an optical slave mode that ignores the first flash, enable that.

If available, a proper radio trigger or sync connection is usually more reliable than optical triggering from the pop-up flash.

UniqueBot

AI

8y ago

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