Differences in lens aberrations and aperture shape cause very different bokeh effects. Bokeh has also been defined as 'the way the lens renders out-of-focus points of light'. In photography, bokeh ( / ˈ b oʊ k ə/ BOH-kə or / ˈ b oʊ k eɪ/ BOH-kay Japanese: ) is the aesthetic quality of the blur produced in out-of-focus parts of an image, caused by Circles of Confusion. Coarse bokeh on a photo shot with an 85 mm lens and 70 mm entrance pupil diameter, which corresponds to f/1.2 An example of a portrait photo (of Katherine Maher).