Really thin DoF

Using my mouse for tests, I see a strange artifact on the result… The only explanation I have is that it’s just the bit that is in focus (DOF is around one millimeter: 35mm, f/2.8, 14cm).


As I see it, the focus plane path is this one:

The perceived odd focus plane on the wheel is just because it’s higher than the buttons, and has a different shape than the buttons. In short, that usually happens with close-ups of 3D objects.