Camera objects have the same attributes and methods as Layer objects, except for source, effect, mask, width, height, anchorPoint, scale, opacity, audioLevels, timeRemap, and all of the material properties.

pointOfInterest

Return type: Property [3].

Returns the camera’s point of interest values in world space.

zoom

Return type: Property.

Returns the camera’s zoom values in pixels.

Here's an expression for the Scale property of a layer that maintains the relative size of the layer in frame while changing the layer's z position (depth) or the camera's Zoom value:

  cam = thisComp.activeCamera;  
  distance = length(sub(position, cam.position));  
  scale * distance / cam.zoom;

depthOfField

Return type: Property.

Returns 1 if the camera’s Depth Of Field property is on, or returns 0 if it is off.

focusDistance

Return type: Property.

Returns the camera’s focus distance value, in pixels.

aperture

Return type: Property.

Returns the camera’s aperture value, in pixels.

blurLevel

Return type: Property.

Returns the camera’s blur level value as a percentage.

active

Return type: Boolean.

Returns true if the camera is the active camera for the composition at the current time: the camera’s Video switch  is on, the current time is between the camera’s In and Out points, and it is the first (topmost) such camera listed in the Timeline panel. Returns false otherwise.