If you are still having trouble finding how to use a distance render in Bryce3D to create a realistic Depth of Field effect I think I can help. Its pretty easy to do. Just render your scene normally in Bryce, then make a new Distance render (keep the positioning and image size the same for both renders.) Open both files in Photoshop (or other 2d editing program) and add the distance render as a layer mask to the original image. You can then use the new mask to select the portions of the image you wish to blur (I recommend using a Gaussian Blur to best simulate DOF.) The only trick might be if you have many objects in your render that are far away or close to the camera. You may have to increase/decrease the brightness & contrast of the distance render to get amount of blurring you want. Ive done this with numerous images and was happy with the results. I hope this helps.