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      11-19-2012, 06:30 PM   #16
techwhiz
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It is possible for it to work.
The camera shutter has to be synced with the flash.
A sensor can detect and flash a strobe much faster than the shutter can close.
A fast shutter can be 1/1000 of a second but it also means that your sensor must be sensitive enough with an aperture large enough so you don't underexpose. The cells force an overexposure and the image gets blown.

Now, here in Ca. some jurisdictions play with the timing so as to force a red light hit even if you enter on a "stale green"/early yellow.

There is a "point of no return" where even if you see the light turn yellow, it would be unsafe to stop and either cause the person behind to stop abruptly or run into you OR get you stuck in the middle of the intersection. Some areas set the timing up so short to cause false positives on the red light cameras for revenue generation.

$350 is expensive because what it does is simply the function of a "salve" flash.
You could do a similar function with a camera slave flash if the photo detector was placed in the right location. A slave flash can be had for $35 or so. One tenth the price of this unit.