^* From the Japanese word for “blur,” boke, or the “quality of blur,” boke-aji, bokeh is nowadays a much-courted aspect of optical quality that deals with how a lens manages the out-of-focus parts of an image—whether it renders them in an attractive or an ill-considered manner. The fact that modern photographers are so fascinated by bokeh is a reminder that lens sharpness is most certainly not the most valuable quality of a good lens—lightness, versatility, speed, and bokeh are all of greater moment to photographic artistry than the ability to make a picture filled with fine detail. The circle of confusion is a term of art and a related topic, dealing with the precisional aspect of photographic depth of field.