i like your approach to build a remote shutter for the SX 70. i am about to do the same. but the shutter i saw all looked the same, two pins. how does it then work with the autofocus of the sonar? does it just focus and shoot right away when you press the button/switch? unfortunately i didnt find any helping post or video online to demonstrate how it works with the sonar autofocus.
thanks for an answer.
First you focus with the button, then snaps the photo with the switch. enjoy!