Drag the camera whose view the Camera Shader should assume here.
If, for example, you would project a wide-angle camera onto a narrow plane the texture would appear skewed. This shader’s settings can be used to deskew the texture. What this shader principally used for is to skew or deskew a projected camera image.
By default, Cinema 4D uses an aspect ratio of 1.333 (width to height). If your projection surface has a different aspect ratio it must be adjusted accordingly.
Use the following calculation to get a projection that is not skewed:
Determine the aspect ration (width:height), divide this value by 1.333 and multiply the result by 100. Enter the result in the Horizontal Scale field (assuming both values were previously set to 100).
These settings define whether or not the Camera Shader will include (i.e. display) the Foreground Object and Background Object when rendering.