Following up on my DIY slave flash project, I thought I’d get something more powerful than that tiny Xenon bulb. I bought the cheapest flash on DX.com – the CY-20. It has a considerably large bulb and as a plus, it has what looks like a tiny window on the front for automatic output control. The main reason for getting this was the 2.5mm jack on the back of the flash that allows it to be externally triggered.
Opening it was easy. Remove the 4 screws that secure the hotshoe mount and go round the casing to release the retaining clips. Surprise surprise, take a look at the sensing window.