Re: [Leica] RE: I've seen the BOKEH!!!

["Dan Post" <dwpost@email.msn.com>]

Simon-
Interesting post on an interesting subject! I was wondering that the
relative size or diameter of the entry aperture of the lenses have any
effect on bokeh and the overall quality of theimage?
The Noctilux has a very large front element, albeit to gather as much light
as possible, and to funnel it into  maw of that great lens.
Perhaps, the large opening, when translated to the interior, the out of
focus portions have a greater aberration due to the relatively large angle
that some of the light must traverse. Center of the lens distance is much
smaller than the edge of the lens distance (to the center axis) and that an
interplay of the same portions of the subject image, from these two
disparate areas of the lens, meld to form this 'bokeh'
Lenses with a relatively small opening, like my older 35 or 28 Elmarit-Rs
don't have that pronounced'glow'
I do know that the 35 Summicron has a better bokeh, to me at least, than
that of the 35 Summaron, and I had ascribed it to the larger front element!
Any thought on that idea?
Dan
- ----- Original Message -----
From: Simon Pulman-Jones <spulmanjones@lbs.ac.uk>
To: <leica-users@mejac.palo-alto.ca.us>
Sent: Monday, August 30, 1999 11:58 AM
Subject: [Leica] RE: I've seen the BOKEH!!!


> I have been comparing pictures shot (wide open) with 35 Summicron (7
> element pre-asph.), 35 Summilux (1960 vintage), 35 Summilux Asph. (second
> version) and Noctilux.  All the pictures are from an ongoing project
> covering the work of a large psychotherapeutic mental health clinic in
> London and are of high contrast, low-light interiors.  More often than not
> the people who are the subjects of the pictures are dimly lit and
> surrounded by bright highlights in the background - typical Leica
available
> light stuff. At first I thought I could detect the unpleasant
> 'double-image' out of focus areas that some people have attributed to the
> 35 Summilux Asph. - but then I started to notice that the other lenses
> sometimes showed this characteristic too. Having gone over and over the
> comparisons I am no longer sure that I can detect any difference between
> the out of focus renditions - each lens seems capable of producing smooth
> or double-image out of focus areas. The real difference seems to come from
> the fact that the double image type of out of focus effect seems to occur
> mostly on back-lit objects in more brightly-lit areas of the picture. The
> 35 Summilux and the Noctilux seem to turn these highlight areas into
smooth
> washes - the Leica glow - presumably because of the high aberration
content
> of these lenses when wide open.  At the opposite extreme,  the 35 Summilux
> Asph. seems to present an odd, sometimes distracting and unpleasant,
> pattern of out of focus highlights - presumably because it is showing the
> highlight artefacts of the lens  in all their complexity rather than
> generalising them into a glow. My hunch is that the differences are not so
> much of 'bokeh' but of the handling of out of focus highlights. Another
> thing that is very noticeable is that the transition between in focus and
> out of focus areas is smoother with the old Summilux than with the Asph. -
> but only because the in-focus areas with the old Summilux are so nearly
out
> of focus (soft) when compared with the Asph.  So the differences that I
can
> see between these lenses are not so much to do with 'bokeh' (as I
> understand it) but with other aspects of the optical fingerprint.  My
> conclusion is that you are not automatically going to get the sought-after
> 'pleasing bokeh' with any particular lens - all of the above lenses have
> sometimes given 'ideal' out of focus areas and sometimes not.  The
> difference in the way that lenses handle contrast and highlights in
> high-contrast, low-light situations is likely to have a far greater effect
> on the look of the picture than any differences in bokeh.  At least that's
> what now seems to me to be the most important factor...
>
> Simon.
>