I think that I need to clarify what I am asking.
I am using a technique from years ago to create a z-depth map in poser.

Make sure all figures and objects are white (not sure if this is needed)
Set the background colour to black.
Set document style to sillhouette.
Select depth in display.
Delete all lights.

The preview now shows a z-depth map that can be saved and used for DOF as well as other things. Unfortunatley I don't know of a way to render this type of image and I cannot  make the preview image (thus the image saved from the preview) to the dimensions of the main image that I will be using it on.

Daz Studio 4.8 and 4.9beta, Blender 2.78, Sketchup, Poser Pro 2014 Game Dev SR5 on Windows 8 Pro x64. Poser Display Units are inches