Attached Link: http://members.home.com/ajtooley/pan.html

This is an example done in Bryce 5. Depth of field is basically using your virtual camera like a real one and focusing in on a particular part of an image, causing the rest of the image to blur. To the best of my knowledge, it can't be done purely in Bryce 4; you need an image editor like Photoshop to add the blur. The way I always did it was to render the image, then select the object I wanted to focus on and do a mask render. Then, in Photoshop, load that mask and apply a gaussian blur to the rest of the image. I'm sure others can illustrate and explain it better than I. But take my word for it: I like it a lot better in Bryce 5, and even though I tend to overuse it right now (because it's so dang COOL), I'd have to say that even normal usage of the feature makes it worth upgrading to B5 for me.