While looking through the cam, scroll your mousewheel back a little and right-click on the frame of it. Your view is literally placed inside the frame of the camera  in 3d view, so just scroll back a little and you can see the edge.

While getting used to the controls, it is usually best to use an empty (spacebar-add-empty) to the scene for the camera to track to. Empties are invisible to the camera, and can be placed exactly where you want the camera to look. 

First , select the camera. Then hold down shift (for selecting more than one object) and select the empty. Now press Ctrl-T and choose Track-To constraint.

Now the camera will be very interested in what the empty is doing. You can also parent the empty to an object to make the camera's view follow the object's movements, or animate the empty for a pan.

Now if we could somehow get some info from the empty to the Map To node we could use it for some easy FOV animation.