Bokeh describes the quality of out-of-focus areas of an image. The word "bokeh" (pronounced as boh-keh) comes from the Japanese word "boke" which means fuzziness. Bokeh isn't the depth of field itself, but the way this unsharpness (usually the background) is displayed on a picture. A lens has good bokeh if the out-of-focus areas are pleasant and don't distract from the subject. The shape of the aperture of a lens has a influence on bokeh. Lenses with more blades in the aperture diaphragm tend to result in more "round" bokeh.
Bokeh (from the Japanese boke (ã¼ã‘), "blur"Mike Johnston, former editor of Photo Techniques magazine, claims to have coined the "bokeh" spelling to suggest the correct pronunciation to English speakers; see his Bokeh in Pictures article referenced below.) is a photographic term referring to out-of-focus (OOF) areas in a photographic image. While this is an and no evidence of formal definition, quantitative, or qualitative framework has been provided, some continue to link this vague, subjectively described quality to various lenses where no obvious consistent link has been demonstrated (see for example http://forums.dpreview.com/forums/read.asp?forum=1030&message=13659518). Unfocused background or foreground is both an inevitability in many photographic situations, and a frequently-used artistic device http://www3.flickr.com/search/?q=bokeh, for example as an attempt to reduce distractions, and emphasise the subject.