To zoom back and forth between a telephoto closeup and a wide angle shot, press the rocker bar on the top left of the camera with the T and W letters on it.
You also can use the manual ring on the front of the camera as a zoom.
To do this, set the ZOOM/FOCUS/IRIS switch on the left front of the camera to ZOOM.
Then use the ring to move between telephoto and wide angle.
The third way to adjust zoom is within the menus on the LCD panel. This allows for a very slow and steady type of zoom.