A currently running thread contained the observation, "but my Dagor has much more bokeh than my Trigor..."
I understand the concept of bokeh as describing how the lens renders the out of focus area. But there seems to be some difference in whether it can be quantified in terms of more or less. (One example I ran across analogized saying one lens has more bokeh than another as like saying one apple has more shape than another.) On the other hand, if it is a function of spherical aberration, as quite a few sources seem to indicate, this can be measured and quantified.
I also wonder if there is any specific quality termed as "bokeh." It seems to be used to describe several different phenomenon. Sometimes it is used to refer to how small points of light are rendered, (see examples at: http://www.kenrockwell.com/tech/bokeh.htm). Sometimes it's used to talk about "swirliness" or field curvature (see figures 2 and 5 at http://www.vanwalree.com/optics/bokeh.html). Sometimes it is used to refer to how "creamy" the gradations in the highlights are...
I guess I'm trying to find out whether "bokeh" can be specifically identified and/or quantified, or if it's a generalized, undefined catch-all word for all out-of-focus rendering. Any enlightenment out there?