I built this simple circuit to shoot sequences of pictures with changing focus points. At the moment, supports Canon EOS DSLRs with LiveView function, support for Nikon DSLRs is planned. Enjoy -> http://www.circuitsathome.com/camera-control/focus-stacking-assistant-for-eos-cameras
Very nice and interesting project. Good work!
I have made a mental note that I need to buy a couple of USB-host shields. :D
This is portable variant of the above -> http://www.circuitsathome.com/camera-control/focus-stacking-assistant-var-mini-build-log , plus couple of pictures made using focus stacking.