You can find the APP on Google Play. This is what it does:
Connect your camera* over Bluetooth with this app and focus bracketing won’t be a problem anymore. Fast and reliable. Focus Bracketing can be completely customized: pick the focus step, the number of pictures you want and the app will do the rest.
Advanced options: Focus Rewind, Focus Test Mode and Pre Bracketing Steps make this app the most advanced companion for professionals. Compatible with external and internal Flash.