Been a long time since I've had calculus, so I don't understand most of the above, lol.
I have, however, used the DOF in Bryce quite a bit. Here are a few observations.
I use DOF with a rpp of 64, which gives good results IMHO. The results depend on how large your objects and scene are, and the camera settings (angle of the lens for instance).
My main gripe: the lens setting for DOF will only go down to .01. Does 5.5 have the ability to enter lower lens settings, like .001 for instance. This would allow greater control, most of what people don't like about Bryce's DOF, I think, is that even on the lowest setting, it is (depending on the effect desired) too strong. The only time I use DOF anyway is when I want the image to focus on a small part of the image. If the image is a landscape, there's no real reason for DOF to me. But if the image is an object or several objects on a tabletop surface, DOF can add a little realism, sort of like an adjustable focus on a real-world camera. Your taste may vary. :^)
Just my 2 cents.

Message edited on: 05/11/2005 14:24

This is not my "second childhood". I'm not finished with the first one yet.

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"I'd like to die peacefully in my sleep like my grandfather....not screaming in terror like the passengers on his bus." - Jack Handy