You don't seem to be looking for changes in the switch input, so it will continually take pictures as long as the switch input remains low.
You've included your sketch, but your question seems to be about how to get Gobetwino to do what you want. In that case you need to know whether the sketch is producing the output you expect (you can check by displaying the output in serial monitor), whether Gobetwino is executing the command you intended (turn on logging in Gobetwino) and whether that command is having the effect you intended.