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

Started Aug 17, 2013 | Discussions thread
ianw2 Regular Member • Posts: 120
Re: High-power LED flash: too good to be true?

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.

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

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