I am trying to model a scene. When I enable a background for the camera view only the image snaps to the edges of the cameras view. Is there any way to change it back to its original size?
In camera-view the picture will be fixed and adjusted to the center of the camera view.
You should dedicate your background picture to any view but camera view by selecting a specific axis in the tool panel. This will enable you to adjust the size and the position of the background image for that view.
And the background image will only be seen if you are in orthographic view (Numpad-5 toggles between orthographic and perspective view.)
If you need a picture as a background picture for a scene, the easiest way is to use the import addon “Import Images as Planes” .
BlenderGuru has a tutorial on that: