Interesting read AG!
I am a very happy owner of the 50mm f2 DZ however, also bokeh wise.
some examples here: some informal recordings of two "first communions"
last week end, one of my little niece camille, the other of good
friends oldest son ruben.
http://lucafeest.fotopic.net/c965405_1.html
http://iwert.fotopic.net/c965578.html
welcome in "traditional belgium"
Iwert.
Op 24-mei-06 om 06:49 heeft AG Schnozz het volgende geschreven:
>> mind translating for the slow-brained types? "cold in the
>> Bokeh" means? should be lower F-stop or just bad lens design?
>
> LOL! You like my new coined term?
>
> Let me describe by example: A prime lens that is symmetrical in
> design will tend to allow the bokeh to "bloom" at a linear rate
> the farther from the plane of focus the OOF highlight is. Not
> only that, but the edge of the highlight continues to soften.
> Changing apertures doesn't change the nature of "bokeh
> expansion", just the rate.
>
> Modern zoom lenses almost always have a limited "bokeh
> expansion". The farther the OOF highight is from the plane of
> focus the less the growth--eventually reaching a point where no
> further expansion occurs. When this happens, the OOF highlights
> will tend to resemble bubbles with a well-defined outer-edge. I
> believe this is due to the aspherical lens elements as well as
> the non-symmetrical nature of nearly all focal lengths the zoom
> lens covers.
>
> You might ask what this has to do with "warmth" of the image.
> Maybe warmth is the wrong term to use, but I believe that this
> progressive bokeh expansion of some classic lenses helps the
> focused-upon subject to seperate from the background better.
>
> Focal-length, aperture and subject distance to background ratio
> all are major factors in determining bokeh. Even blade shape.
> But lenses that freely allow the "bokeh bubbles" (another coined
> term) to expand freely will give a softer, smoother background.
>
> Back to "warmth". I believe where I'm going with this is a
> rather radical concept: We all know that an OOF highlight will
> bleed into the surrounding shadow area. But I also believe that
> the OOF shadow will bleed into the highlights. My 100/2.8 with
> about 25mm of extension (1:4 magnification) will lose almost 1/2
> a stop in a background that is greater than 2x the focused
> distance. This is above and beyond the normal loss due to
> extension. The "light falloff" further helps bring the subject
> out from the background. Depending on the nature of the film or
> sensor, this under-exposureness may trend towards an actual
> warming of the scene.
>
> I definitely wouldn't call a modern lens "flawed" or "bad".
> They're more accurate and sharper than anything that fits one of
> my OMs. Furthermore, I believe the aspherical lens elements
> create a thicker plane of focus. Instead of perfect focus being
> a plane that intersects the scene, it actually has some depth
> with the modern lenses. At any given aperture, my DZ 14-54 tends
> to have more in focus than my 50/3.5 or 35/2.8.
>
> AG
>
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