Originally Posted by
HDNitehawk
There is no substitute for getting it right in the camera to start with, there are only repairs you can do to the pictures later. I can't see how it would be a good substitute if you have to individual touch each of your photo's to get the DOF and Bokeh you want, when with a turn of a dial on your camera you can set it instantly.
If you couldn't afford a fast lens I see how a person might use this, but it still costs you. You will end up spending your time with additional processing to save the cost of the faster lens.
+1 for Sean's points. If it were just about DOF I wouldn't own the 70-200mm F/2.8L II, I would just go for the F/4 version and carry a lighter lens. It is the Wide open F/2.8 and it's ability to perform in lower light that makes me choose the F/2.8 version.