I'm working on an animation, and in this particular scene, I have a close up of a naval gun turret. I wanted to focus on the middle gun, but the defocus node gives me trouble. In the image below, I have the camera focused right and all, but the way the in-focus cannon interacts with the one in front of it looks weird.
See how it's got that harsh line between the blur and the sharp one? Ideally, I'd want the blurred foreground to sort of fade onto the mid-ground, which would make it look more natural. Here are my camera settings and node setup: