Archived posting to the Leica Users Group, 2003/09/11
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At 6:02 PM -0400 9/10/03, Buzz Hausner wrote:
>One difference between the spherical and aspherical 35mm Summicrons is
>that the spherical version has ten diaphragm blades while the aspherical
>has eight. I believe that this is the reason for the spherical versions
>much admired buttery-smooth bokeh as compared to the aspherical's more
>"etched" bokeh. It still has nothing to do with the Fifties and Sixties
>era optics, though.
>
> Buzz
Bokeh is much more a matter of under corrected spherical aberration
than number of diaphragm blades. The number of blades only comes into
play when the spherical aberrations have been highly corrected and
specular highlights are in the out-of-focus areas, but even then, the
shape of the blades is much more important than the number, and
additionally, an odd number is better than either adjacent even
number.
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* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com
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