Selective Focus
The deliberate use of a narrow zone of sharpness to direct attention to one element and suppress everything else.
In depth
Selective focus is a compositional decision made with a technical control: the sharp region becomes the subject regardless of size or position, because the eye goes to detail. Used carelessly it produces pictures where nothing is legible; used deliberately it can carry the entire meaning of a frame.
Examples in practice
A wedding ring held sharp against a completely dissolved church interior makes the object the story.