The moment you enter the camera app, the G3 starts emitting a cone-shaped laser beam from a window just to the side of the camera. The phone then measures how long it takes for the light to bounce back to it and thus gets a reading of how far away the subject of the photo is.
Time to autofocus? 276 milliseconds. Touch where you want to focus and the G3 will focus and take the shot too. The Samsung Galaxy S5 uses a hybrid contrast & phase detection autofocus system and takes 0.3 seconds (300 milliseconds) to focus. LG’s camera UI is minimal as can be: one button for menu and a back button.