drgeoff wrote: ↑
Tue Nov 07, 2017 9:27 pm
It seems to be nothing more than a normally open switch which is momentarily closed when the shutter is opened. The internet has many tutorials on attaching switches to RPi GPIOs.
Yep, thats what it is, at least for non-dedicated hot-shoes. The PC flash connector is the same. The camera expects a positive voltage on the centre pin which it then connects to the outside of the shoe when the shutter fires.
Older cameras use a mechicanical switch, later ones may do it electronically.
The only real gotcha I can think of is doing this at the same time as connecting a flash gun. Not so much the wiring but the voltage output by the gun. Bulb flash guns generally used a 22v battery. Xenon flashgun have lower voltage battery packs (often around 6v) but it's common for them to put the voltage (several 1000) from their internal capacitor across the hotshoe. Either one will fry a pi.
Check the specs for your camera and any flash gun you might want to use.