Bokeh is often discussed as if it were a purely emotional quality, something photographers respond to instinctively rather than analytically. A background feels creamy, or nervous, or harsh, and that is that. But the visual character of out-of-focus rendering is deeply tied to engineering decisions, manufacturing tolerances, and the physical geometry of the lens itself. The shape and cleanliness of blurred highlights do not happen by accident. They are the consequence of how light passes through curved glass surfaces, how aberrations are corrected or allowed to remain, and how precisely those surfaces are produced.