Bokeh (English. bokeh; YAP. 暈け or ボケ – “blurring”) is a characteristic of the aesthetic qualities of the image area that lies out of focus, i.e. outside the grip area. Bokeh has nothing to do with sharpness: two lenses that depict objects in focus equally sharply can have a completely different blur pattern, the subjective artistic merits of which are described by the term bokeh.
An ideal lens from an engineering point of view focuses light from a point source in the form of a regular cone. When the tip of the cone touches the plane of the matrix or the camera film, the image is in focus and the photo gets an extremely small point. Continue reading