http://answers.unity3d.com/questions/147988/how-to-pause-the-main-camera-.html
I would simply pause the game with Time.timeScale = 0, and then do the following commands to Camera.main:
- Save the Camera's CullingMask into a variable.
- Save the Camera's ClearFlags into a varible.
- Set the Camera's ClearFlags to Nothing. This will make it so that the previous frame's image will not be cleared.
- Set the Camer'as Culling Mask to 0. This makes it so that NOTHING is rendered.
- The Camera should now display the image of the previous frame permanently.
- When the game is unpaused, reset the CullingMask and ClearFlags values to what they were before.
Also, when you setup a script to do this, DO NOT use Update or LateUpdate to perform these tasks because they will not be called if the game is paused.
http://forum.unity3d.com/threads/47069-Stop-Camera-Rendering
Set the camera object inactive or disable the camera component.
GameObject.Find only finds active objects.