Raz, set the focal length how you want it, then set the scale of the camera to 100%, then parent it to your object. This will fix the problem.

Fore some reason a Poser4 (I don't know about P5) camera won't track its parent properly if the camera scale isn't 100%. You also get this bug if you parent an object to the camera, tracking won't be correct unless the scale of the camera is 100%.

Also note that when you change the focal length of a camera Poser automatically changes the scale of the camera.