Maximum 15mm Blur
Using a widest-available aperture at the minimum-available focus distance with a very distant background produces the maximum amount of blur a lens is capable of. With its wide angle of view, a 15mm lens does not enlarge the distant out-of-focus objects enough to make them undistinguishable. Composing with a wide angle lens can be challenging due to background distrations present in the frame.
Camera and Lens Settings
15mm f/2.8 1/800s ISO 100 5760 x 3840px