[Leica] [Leica} existential pleasures of engineering (3)

[Erwin Puts <imxputs@knoware.nl>]

Every design program I know of (and yes I do know the Leica program too) has
been based on the sharpness plane that is infinitesimal 'thin' or two
dimensional. On of the best test patterns still is a large black piece of
paper with very small holes punched into the paper. Lit from behind the forms
and color fringes around the holes give you much info about the aberrations
left in the design. Aberrations that will show up in every picture that is
taken from a flat and a three dimensional object alike. The impression of
three dimensionality may be based on the residual aberrations left in the
optical system, but there is not one single theoretical or practical argument
why sinusoidal test patterns or point spread functions could not represent the
real world faithfully. Any reliable test procedure (at least mine does) will
take into account all these theoretical topics and practical inferences to
ensure that the results are useful for any user of Leica equipment who wishes
to select lenses on the basis of real image qualities. The discussion should
include the unsharpness area or depth of field. It is often stated that the
elusive Leica glow is part of the answer as this characteristic is visible to
anyone, but not testable by normal methods. Well I am not agent Mulder so I am
unable to comment on this 'glow'. What I do know is that the characteristics
of the unsharpness area are not specifically designed into the system, but are
simply the result of the optimization of the aberrations as defined for the
focal plane. Nothing mysteriously here.
The so-called 'light box' test might be preferred as a tool to quickly
convince editors to select images on subjective and impressionistic impulses
and to prove that the basic image quality (sharpness and color rendition) is
good enough. To study the finer points of image quality and the real
differences between several Leica lenses a much more elaborated suit of
equipment is necessary.
Do we want or need to study these differences?
Some would say no, others are inclined to say yes. Persons with an engineering
bias will enjoy discussing these finer points and in doing so try to find the
truth of what are the best Leica lenses available today. There is nothing
wrong with such an attitude. The measurement and comparative assessment of
lens characteristics is a fascinating part of the Leica world. Anyone who does
not wish to indulge in this activity can choose to leave it and study the
language of the great Leica photographers. The language of art and the
language of optics and engineering may be different but can be mastered both
at the same time. That is the real challenge in my view. And Leica users are
fortunate that the Leica products support both views and even integrate them
in a fascinating manner.

The engineering standards to which Leicas are being designed and constructed
are very high indeed and I think it a legitimate pleasure to enjoy and study
these standards. I also think that taking pictures with a Leica, sensing the
high level of precision engineering while taking pictures greatly enhances the
pleasure of using a Leica.
Of course these pictures may not be great art, but I think it a bit
narrow-minded to assume that Leicas may only be used in the proper way by
'vision-people'. I am a great admirer of HCB, but I could not make one picture
in his style and quality. I still can admire craftsmanship in an instrument
and use it accordingly.
The upshot of this long story then is quite simple:
Leica M systems have been designed and constructed as precision engineering
instruments that are dedicated to taking pictures in the style of the artless
art of the snapshot. You can admire and enjoy both aspects of this fine
instrument or you can choose to address one of both aspects. In any case it is
up to any user to make up his/her mind. There is not one proper way to use a
Leica, nor a canonized way to take pictures with a Leica.
There is only the pleasure of owning and using and studying this very
remarkable instrument of photographic technique.