Simultaneous electronic shutter release for multiple Lumix G7 cameras

Question

I'm trying to trigger six Panasonic Lumix G7 cameras at once.

The trigger mechanism uses a four pole 2.5 mm plug, some resistors and two switches. With no switch closed there is 41 kilohms of resistance. To trigger the focus, you reduce that to 5 kilohms. To trigger the photograph or video start you allow 2 kilohms of resistance.

So much I learnt from this great blog post: http://www.robotroom.com/Macro-Photography-2.html

Wired this way it triggers a single camera just fine. However, when you add additional cameras to the circuit, it doesn't work anymore. I'm guessing that the resistance is no longer correct, because now the focus trigger does nothing (I think) and a shutter release trigger makes one camera focus.

When I was 11 I was the proud owner of a DSE Funway into Electronics set. I'm afraid I've learnt nothing much since then.

Any way to wire this up so that the resistance is correct for all the cameras? Ideally I could add more than 6 cameras in the future following the same method.

My fall back are independent circuits with a mechanical switch closing them all independently, but 1/100 second accuracy would be a big help here, so I'd love to do it right.

Cheers,

Red

Answer 1

ordinary mechanical relays are fast enough to manage 1/1000 second accuracy

have one set of relay cntacts and one set of resistors for each camera. (or two contacts if you needs focus and shutter)

solid-state relays can be non-ideal in interesting ways, but the right one could work too,

or you could do it in discrete transistors like this;

^{simulate this circuit – Schematic created using CircuitLab}

(immagine that repeating bit four more times)