And, if in P4 for a while....

You can selectively and progressively blur in a paint app by hand, but you may find this trick faster.

Poser 4's Depth Cueings transparency effect is calculated automatically and applied progressively, starting at the lens (most opaque) to the object furthest from the camera (most transparent) whether those objects are visible or not.

You cant change the front setting, as it starts at the lens, but you can cheat the back setting by adjusting the location of an invisible prop in the background.

An oldie-but-goodie trick for simulating DOF in P4 is to render twice. Once normal (without Depth Cue), then again using Depth Cue and with a blurred version of the first render as an imported Background.

The Depth Cueing transparency effects will increasingly reveal more of the blurred background through the objects further from the camera.

Still requires one step in a paint app, but you can quickly apply a general blur to the whole image and then let Pose's Depth Cue function do the hard work of determining how much blur to make visible at different distances.

Revised from PoserPros post:
http://poserpros.daz3d.com/forums/viewtopic.php?p=85203

originally posted at PFO