The funny things is, the definition of bokeh is something even Ken Rockwell can get right. In one sentence. (of course he then goes on as he does, but that first sentence is spot on.)
I don't think that I have seen Gasrocks take the time to explain what he means in a long time, but I will say he used to, ...
trouble is, even when you do take the time, you still get beat up and or ignored
For the record;
someone who usually has his head in a dark place but gets this one spot on wrote:
Bokeh describes the rendition of out-of-focus points of light.
Rick- who elaborates a little- Denny wrote:
We should keep in mind a few points when discussing bokeh:
1. Bokeh is about the rendering of out-of-focus highlights, not specifically about depth of field. Out-of-focus highlights may be rendered with a harsh edge, a neutral edge, or a faded edge. The neutral edge shows a lens with the best overall correction, but the faded edge is the thing most people are meaning when they talk of good bokeh.
2. Bokeh is not about quantity of blur. You'll get more blur with longer camera-to-subject distances (allowed by longer lenses) and with wider apertures. It's quite possible that a fast lens with poor bokeh will provide a more nicely blurred background than a slower lens with excellent bokeh. The Canon 70-200/4L provides excellent bokeh, but it won't blur the background as much as an 85/1.8 when used at 1.8, though you might get close by backing up and using the 200mm end. A photo with profound use of selective focus to isolate the subject is not necessarily an example of good bokeh, but rather an example of selective focus. If the blur is smooth rather than edgy or clumpy, then it also has good bokeh. Good bokeh is mostly what produces the creamy three-dimensional effect for which old Sonnars are justifiably famous.
3. Bokeh is not about aperture shape, though you can see the shape of the aperture in out-of-focus highlights, especially if the lens has bright-edge bokeh. Some lenses have poor bokeh even wide open when their apertures are round.
4. It's not about lens quality. In fact, good bokeh depends on a bit of undercorrected spherical aberration, though that usually is corrected out at smaller apertures.
5. You can't generalize about bokeh. Lens design is the primary influence, but not the sole influence, and can be overcome by other factors. Each lens really should be evaluated on its own merits. Lenses with more aperture blades may or may not have smoother bokeh. Lenses with more or fewer elements, faster or slower, prime or zoom, or any of the other things people generalize about, may have good or bad bokeh.
6. A bare midriff always looks better than a blurred background, no matter how nicely blurred it is. Therefore, the best bokeh is the one where the subject is so compelling that nobody cares about the background.
It's not hard to come by a correct definition, they happen to accurate in the first too hits when you google "bokeh", Wikipedia and yes, K.R.
As mentioned, K.R.'s first sentence is spot on,
Unfortunately, the editor/s of wikipedia have chosen to leave the correct meaning to the second sentence in the Wiki definition,. and apparently few people read that far in... even after Gasrocks has made mention of the inaccurate use on this forum so many times that he gets called names for it. I'm really not sure that should be classified as his fault. But that's just my P.O.V. I guess.