Leica M. 75mm Summarit. f2 @ 1/500 second.

Nothing draws your eye to a subject like limited Depth of Field. Using a lens wide open, especially a telephoto lens, tends to throw backgrounds out of focus, making the sharp subject stand out very clearly. It doesn’t have to be as extreme as this shot of a snuff bottle in Mongolia but your eye is strongly attracted to areas of high contrast, so having a sharp subject against a lower contrast background adds the illusion of depth.