Re: [Leica] Bokeh

[Charles Dunlap <cdunlap@es.UCSC.EDU>]

>Charles,
>Are you saying then that when a Lug member enthusiastically announces "lots
>of Bokeh" regarding a lens for sale - or in describing how a lens performs =
- -
>he/she is using the term improperly ?

Saying "lots of Bokeh" is meaningless. The question is whether the Bokeh is
pleasing or not. The Bokeh (i.e. out of focus imaging) of some lenses is
unpleasant.

> Or is he/she saying that there is
>Bokeh but it may or may not be acceptable?

She probably means that the Bokeh is pleasant, meaning that the out of
focus areas are more like Monet than Miro. But reading this meaning into
the statement is generous guesswork. To be more informative she should say
"a beatiful, Impressionistic Bokeh" or something like that.

>Don=EDt all lenses have the same degree of out of focus effect at a given
>opening but that effect varies in quality with the lens design, thus Bokeh?

Well, all lenses of the same focal length should provide the same depth of
field at the same aperture, if that's what you mean. And yes, Bokeh would
be the general term describing out of focus imaging.

>Finally, if Bokeh is the "quality" or "pleasant quality" of out of focus
>areas in a photograph, would not "lots of Bokeh" mean "lots of pleasing out
>of focus rendition"?

But Bokeh doesn't mean the "quality" or "pleasant quality," that's the
point; the meaning isn't a or b. It is a noun naming one property of a
lens: the way it renders the out of focus areas. This rendering can be ugly
or pretty or sometimes ugly or sometimes pretty or neither ugly nor pretty.
Every lens made that cannot focus from 0 to infinity has Bokeh, and lots of
it. The question is what is the Bokeh like at a particular aperture and
particular distance from the plane of focus.

Take the latest 50 Summicron-M for example. The Bokeh of objects closer to
the lens than the plane of focus at f/2 is very soft: the edges are very
diffuse and the image of the objects is spread out. In the background,
however, the Bokeh is not as soft: straight lines are slightly doubled and
the edges of objects are slightly more defined than in the foreground. Part
of learning the lens is learning how these renderings affect the intended
photograph.

- -Charlie
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             Charles E. Dunlap
         Earth Sciences Department
          University of California
            Santa Cruz, CA 95064
Tel.: (408) 459-5228    Fax.: (408) 459-3074

         mailto:cdunlap@es.ucsc.edu
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