Archived posting to the Leica Users Group, 2000/11/26

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Subject: [Leica] Leica bokeh test or trial
From: "Frank Dernie" <Frank.Dernie@btinternet.com>
Date: Sun, 26 Nov 2000 13:43:02 +0000

I would like to jump to Mike's defence here.
Both Mike and Erwin make valuable posts in their different ways.
Perhaps they should not read each other's!
As an engineer who has spent most of my life on research I am familiar with
the importance of a methodical approach. Erwin's posts and web sites are
valuable and interesting but in the case of so called boke the problem is in
defining what constitutes "good" boke.
Definition and contrast are easy to define and measurement techniques are
well developed. In what units will boke be defined? By what measure could it
be considered to be good? This is not a quantified characteristic of a lens
and, as such can not be measured.
Some people do not even notice its existence. My very amateur opinion is
that the nature of these oof areas probably depends on the priorities of
aberration correction chosen by the lens designer. If this is so the
designers probably know which abberations have a greater effect - certainly
ranges of lenses have a similar look in general - if they do they will
certainly not IME publish their results for fear of giving any information
to the competition.

For my personal use I find boke to be one of the most important aspects of
my pictures. If one usually photographs flat subjects or stopped down a lot
it is of little consequence. If OTOH one shoots outside fairly wide open
frequently the majority of the frame is oof and ugly blodges distract from
the subject. I would imagine this is important to most Leica photogs because
much of the advantage of Leica lenses is in their wide open performance.
My Leica lenses are generally good in this respect. My only recent
disappointment was the new "Voigtlander" 50 f1.5. The boke is so harsh that
I find the lens unusable wide open thus negating the point in it being a
fast lens IMO.
Those on the list a long time may remember the discussions we had about a
year ago on this lens so I won't expand further now.
cheers Frank

> Mike Johnston wrote
>>>>
>
> It's really gotten to a ludicrous level when we start arguing about bokeh in
> words and pseudoscience. For heaven's sake, this stuff isn't brain surgery.
> Just take a bunch of pictures with blur in them and look at the blur. We
> don't have to _quantify_ what's going on; it's enough just to _look_ at it.
> It's there to see.
>
> <<<<
>
> You don't _have_ to quantify what's going on, but maybe it would be
> _interesting_ to try to do so. I don't think you can argue that it's wrong
> to want to do that.
>
> Erwin's approach is just different from yours, so why come down on it so
> heavily? BTW, what makes it pseudoscience rather than science? I would have
> thought that the urge to measure and understand is pretty scientific.
>
> Rob (who is finding these Pavlovian responses to Erwin tiresome).