Aye, you can isolate any object you want using Object Mask rendering, Drawbridge. This method is, in fact, the same method that Bryce uses when calculating it's internal DOF. You simply mix the Distance Mask and the Object mask as layers in Photoshop. You can do this by Multiplying or Screening your Object render against your Distance render. If you need more clarity from your Distance render, then you simply adjust the levels, or use Autocontrast. All of this in, like I said, 1/1000th the time that it takes Bryce. So, to answer your question, Yes. You can do it easier, faster, and with cleaner results in postwork. Try this technique on your above scene, you will find it much cleaner and more realistic. Or is your above scene actually a photo (grins!)??? And my last point : you cannot realistially animate Brycean DOF. You cannot even change the DOF over a timeline, or tween it, or keyframe it. You can do all of this with postwork animation, in After Effects, easily, and still have countless hours less downtime than if you sit around waiting for Bryce to clean up it's inherent graininess. Just because you CAN use an internal option doesn't mean you should... And in the time it takes you to render one such monstrosity, you could be on to your next scene and be rendering other things...