I tried this out and I can’t seem to cause a black render. I’m trying both the default Max camera and the Brazil2 camera. Would you be able to supply a sample scene that I can look at?
Regarding the target distance vs. focal depth, our current behavior is to ignore any settings in the Max camera’s multi-pass effects. For Brazil2 cameras we use the Focus Distance if the ON checkbox is checked in the Depth Of Field rollout, and the target distance otherwise.