How can I sync an LED with a camera shutter?
Here is an educated guess as to how this output is intended to be used.
Your camera probably has an optocoupled transistor output. A normal photo flash is fired by pulling the pin signal down to the outer shell. Modern flashes have &lt; 12V on the signal, so a photo transistor will work. Older flashes can have hundreds of volts on the pin, you must use a photo SCR/triac (available in higher voltages) to fire these.
Yours is most likely a photo transistor. When I fire my photo flashes with DIY setups, I use this circuit, similar to a camera output:

First, run a test to confirm the output circuit. The test circuit below will be unlikely to hurt anything. If you get the expected result, then move on to design an LED driver.
If the negative pulse width is acceptable, try the next paragraph. If not, you will need to shorten or stretch the pulse.
If you want to substitute an LED for the photo flash, the next two circuits are two options. I wouldn't use a V+ greater than 20V without adding another stage (unless you can find a spec for the camera opto output). The values will depend on your LED array characteristics. If V+ is 12V or less, you don't need the Zeners.
Be aware that LEDs when pulsed are no where near as bright as a Xenon flash. Also, if your LED bulb has a built-in power converter, you won't be able to pulse it.



simulate this circuit &ndash; Schematic created using CircuitLab