Well depends on what program you are using. I would think you would use 100% for over the lock,to make it stay sharp,and the background to go blured. The one I attached was taking your original,and then using the magnetic laso to select the lock,then inverse the selection. All I did then was to use gausian blur set to 2, and went back over the edges of the lock with the blur tool set at 50% and at 15 pixels to smooth the edges.