Right-click an empty area of the scene and select Switch Views from the marking menu that appears.
(Then select Perspective, Top, Side, or Front views.)
In the Object List, right-click a camera name (Perspective, Top, Side, or Front) and select Look Through from the menu that appears.
NoteYou can also click and drag the ViewCube to quickly and easily switch between perspective and orthographic views of your model. See Navigate the 3D view.
Tip You can change the default camera rotation behavior in the Camera preferences (Windows > Preferences).