[Leica] Noct, glass and coating (again)

[Erwin Puts <imxputs@knoware.nl>]

About the Noctilux I noted in the PT article, that the Noct is a competent
performer at smaller apertures, but will not equal or surpass the
Summicron-M. The same statement works for the Summilux-M, with the proviso
that the 'lux is somewhat  weaker in image quality than the 'cron at the
said small apertures. So the upshot is this:  the Noct gives excellent
quality at smaller aperures, but due to its design the rendition of very
fine details at these apertures lacks the crispness of the 'cron. And if
you need the crispest rendition of extremely fine detail the Noct has to
give up. When you shoot at 5.6 with both lenses on a fine grain B&W film
and enlarge 10 or 12 times the softer rendering of small details of the
Noct is visible.
As I am a freak as everyone knows by now I would advise to have the Noct
AND add a Summicron to have the best of all possible worlds.

About glass:
The info on the Lug drawn fromvarious sources has snippets of truths here
and there. The real story is this. In the older days Leica had a small
research lab, where they produced glass to specs of the optics design
department. These specs were sent to Schott ( a Zeiss subsidiary) who
produced this glass AND adopted it in their catalogue as standard glass,
available to everyone who is willing to pay the price of the glass. Later
on they stopped the research completely as enough standard glass of all
types of specs were available from various manufacturers (Schott, Hoya,
Corning and others)  to satisfy their needs. Generally he glass factories
would not produce the small quantities of glass Leica needs only for their
specs. The socalled Noct glass was outsourced to Schott, but they could not
get it right so Leica had to produce this glass (and only this glass)
themselves.
Nowadays Leica does not design glass and no company produces "Leica glass"
for Leica as patented glass unavailable to others.
Leica now uses the standard glass from the standard catalogues from
manufacturers. It is true that many glass types in the standard Schott
catalogue had their origins in Leica research.
There is no "Leica glass" to explain the intriguing capabilities of Leica
lenses. Just the brains and creativity of the designers and some other
secret ingredients.

On coating:
as coating is in integral part of the design process it does not make sense
to single out one characteristic as superior above any other. Coating is a
highly complex design issue and the statement that multicoating of all lens
surfaces is per definition superior to a mix of coating techniques is not
true. That Pentax saw in the early days a competitive marketing advantage
in promoting  a technique that Zeiss already used, is a commercial topic.
As I noted in my earlier post: sales brochures  AND sales persons then AND
now are not the sources we should refer to when discussing technical or
scientific matters.


Erwin