The Blender NumPad also allows you to control the zoom. However, this may not work if you have Emulate NumPad enabled. If you do, skip to the next Time for action – making the camera see what you do section:
Press the + (plus) key on the NumPad several times to zoom in.
Press the - (minus) key on the NumPad several times to zoom out.
Press the . (period) key on the NumPad to center on the selected object and zoom into it. If you are using the NumPad emulator, this will not work; but you can select View on the 3D View header and find View Selected on the pop-up menu, as shown in the following screenshot:
Press the Home key on the keyboard to zoom out to show the entire scene. This is not the Home key on the NumPad. Press fn + left arrow if you are using a Mac with no Home key.