Tap the zoom knob to switch to 2.0x optical zoom. Tap it again to change back to 1.0x.
To zoom steadily and automatically when recording video, do the following:
In landscape orientation, swipe left to zoom in or swipe right to zoom out automatically.
Here are different ways to zoom in or out manually:
In portrait orientation, drag the knob to the right to zoom in or to the left to zoom out. In landscape orientation, drag the knob up or down to zoom in or out. The farther you drag the knob on the zoom bar, the faster the zoom speed.