Attached Link: http://art.aprilgem.com/bryce/bryce11.html

...and further adjustment. From here, you can invert the mask if you want so that your area of focus is black, so that when you select the mask, it's a much more precise selection of what you'd want blurred -- the object being the least blurred. Hope this makes sense to people. I've been using this technique forever. It's how I did the image linked.