High-power LED flash: too good to be true?

Started Aug 17, 2013 | Discussions thread
Phil Veteran Member • Posts: 3,141
Re: High-power LED flash: too good to be true?

ianw2 wrote:

Phil wrote:

Brent Allen Thale wrote:

They posted a lighting setup diagram where they indicate the flash duration is set to 1/500 second, and the camera shutter speed is also 1/500 second. I don't understand how this is possible since at 1/500 second, the sensor on the 5D Mark II will never be completely open, so how are they evenly exposing the frame with a flash duration of 1/500?


The Pocket Wizard TTL triggers for Canon EX flashes have a hyper sync mode that shaves the flash timing closer allowing a 2x sync speed. I'd have to research what's the fastest I've been able to use. 1/500th sounds high but it's not too far off, so I'd say this was at least possible.

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Phil Agur
5DMKII - 5DMKII Dual Body Bag - Go 'L' and don't look back!

Nikon also have a mode on their flashes that allows shutter speeds greater than the sync speed. I expect Canon have an equivalent system.

All these systems work either by extending the flash duration (the Nikon system which fires a series of smaller flashes), or taking advantage of the longer duration of the flash (the Pocket Wizard system). The Pocketwizard system works best with studio flashes which are generally more powerful and have a longer duration than Speedlights, but some modest gains have been reported with Speedlights (and Speedlites).

For such a system to work the flash must stay on while the curtain is open. If the camera shutter speed is 1/500 second, the curtain will be open for longer than this. I expect they fire the flash multiple times so each part of the sensor receives a flash duration of 1/500 second.

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Ian Wiese


There are 3 modes available with the PW in the system. Canon & Nikon both have normal sync and high speed sync (where the flash strobes at a fast rate to minimize the impact of flashing while the sensor is partially blocked by the curtains) but the PW set-up adds what they call hyper sync, a third mode.

Hyper sync is still a single full power flash, like a normal flash event, but uses a refined curtain timing while telling the camera the flash is set to high speed sync. The result is you can get 2X or a little more than the camera's normal sync speed without catching a curtain while having a full power flash event available.

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Phil Agur
5DMKII - 5DMKII Dual Body Bag - Go 'L' and don't look back!

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