Thank you; that's exactly what I want to do - use the Arduino to trigger the shutter. But all the links I've gone to so far are either:
a) how to make an infra-red shutter release, which is way too complex for my needs, or
b) tell me that I need to expose just the red & black cores to a mini-B plug, but omit to say which is the correct core to put the +5 through.
So now, I'm off to wreck a few USB cables before I set out to master Arduino.
Thanks again
JB