Imagine you work in some 3D application where you can control the camera and view data graphs from different points of view, controlling camera position and direction. Sometimes you might get lost in 3D - you don't know where's start and where's top.
You need to reset the camera to default viewing point. How would you design a small icon that resets the camera view to default view?
EDIT: To answer some additional questions. Camera control is done through mouse buttons (LMB - rotate, RMB - pan, Wheel - zoom). Controls for camera are also repeated in UI, but since they are much cumbersome I would not like to show them, in essence they are buttons you press to move left/right/up/down/rotate/zoom by a certain value.
The default value does not only zooms out, but also resets viewing angles to 45/35 degrees and positions the camera precisely at plot middle.
I'm afraid to introduce the camera symbol because it is not used anywhere else in UI, the end-user does not have to know about existence of a Camera. He sees the plot he can move and rotate, so to rephrase the question - I'm more looking for an idea for an icon to reset plot position and rotation. In my question I referred to Camera just for convenience sake (we nerdy people know about cameras and angles, but normal people don't need those extra entities).