Poser light seems to originate from a point no matter what your light or shadowcam settings are. RayTraced or Shadowmapped. This causes big problems if you are trying to match say a cameraflash or even a lightbulb whose point of origins are much wider.

What I mean is, your object will always be struck from a narrow angle like a cone and will always cast a shadow where there should'nt be one.

Maybe a 2 or more light tandem is really needed to straighten the line.