Renszu-Photoworks does have the capability of z-depth rendering. Here is a progression to give you an idea of what Rensu was talking about Norah. You can even uses the raw render below and the depth cue rendered image to approximate DOF. As you can see you dont really have to go to the effort of doing a depth cue render if you already have a picture in your minds eye of what is farthest and nearest to the viewer
LIke Ive said before-Photoworks is not the best rendering system by any means but it can do decent stuff