Originally posted by glad2badad:
Last day of voting on the Bokeh challenge and STILL discussing bokeh and the various definitions. This has certainly been a hot topic. :-) I'm not proclaiming to be an expert, FAR FAR from it - but I do like to see all sides represented fairly, especially when the subject matter is actively being voted on in a current challenge.
Therefore - here is a definition of bokeh that I find interesting and should be considered by active voters.
The following is an excerpt from What is Bokeh by KenRockwell.
Fig. 1. Poor Bokeh. This is a greatly magnified blur circle showing very poor bokeh. Note how the edge is sharply defined and even emphasized for a point that is supposed to be out-of-focus, and that the center is dim.
Fig 2. Neutral Bokeh. This is a a technically perfect and evenly illuminated blur circle. This isn't good either for bokeh, because the edge is still well defined. Out-of-focus objects, either points of light or lines, can effectively create reasonably sharp lines in the image due to the edges of the sharp blur circle. This is the blur circle from with most modern lenses designed to be "perfect."
Fig. 3. Good Bokeh. Here is what we want. This is great for bokeh since the edge is completely undefined. This also is the result of the same spherical aberration, but in the opposite direction, of the poor example seen in Fig. 1. This is where art and engineering start to diverge, since the better looking image is the result of an imperfection. Perfect bokeh demands a Gaussian blur circle distribution, and lenses are designed for the neutral example shown in 2.) above.