I know it has been asked earlier, and I have the "schematic" of it. 3 wires isn't rocket science.

I am building a shutter control system and am going to use opto couplers to "switch" (control) the camera.

But opto couplers are polarity sensitive.

Does anyone know which way those tricky little electrons are running?

It isn't too much of a problem for me, I have a DMM and can do it, but thought I would ask anyway.

Thanks in advance.