Command entry:Click or right-click the Point-Of-View (POV) viewport label. 
POV viewport label menu Cameras Cameras submenu Choose a camera.
A Camera viewport shows the view from a camera, looking in the direction the camera is aimed.
Camera viewport controls include the following. Two of these controls are available in all viewports.
Zoom Extents All, Zoom Extents All Selected (available in all viewports)
Maximize Viewport Toggle (available in all viewports)
Activate a Camera view from the Point-Of-View (POV) viewport label menu. If the scene contains more than 10 cameras, the last entry in the list is "More Cameras.” Choose this to display the Choose A View dialog, which shows the complete list.
If a single camera is selected and you press C, the active viewport switches to the view from that camera. If, when you press C, the scene contains more than one camera and no camera or multiple cameras are selected, the Select Camera dialog appears; choose a camera from the list.
To undo changes to a Camera viewport, do one of the following:
Click Undo on the Quick Access toolbar.
The buttons on this flyout replace the Zoom button when a Camera viewport is active. Use them to move the camera and/or its target along the camera's main axis, toward or away from what the camera is pointing at.
Perspective performs a combination of FOV and Dolly for target cameras and free cameras. It increases the amount of perspective flare, while maintaining the composition of the scene.
Roll Camera rotates a target camera about its line of sight, and rotates a free camera about its local Z axis.
Truck Camera moves the camera parallel to the view plane.
Orbit Camera rotates a camera about the target. Pan Camera rotates the target about the camera.
