Re: [Leica] design 2

["mdelman" <mdelman@rochester.rr.com>]

Erwin:

Thanks for the last several postings on lens design.  Very helpful in
understanding the subject.

- -Mark
- ----- Original Message -----
From: "Erwin Puts" <imxputs@ision.nl>
To: <leica-users@mejac.palo-alto.ca.us>
Sent: Sunday, April 08, 2001 4:47 AM
Subject: [Leica] design 2


> It is very sensible for a designer not  to try to optimize a lens beyond
> the level that the mechanical tolerances can allow for.
>
> Some people have objected to my remarks  that many Cosina lenses
> decentred elements as it has been interpreted as Cosina-bashing. It is
> not. Some older Leica lenses show this decentring too: it is the
> consequence of the tolerance level that is accepted or =
> defined as the level of precision that is required for a given level of
> image quality or a given level of manufacturing precision. A designer
> and the company in which (s)he works knows what is possible or required
> and engineering is not sorcery: any additional minute of work costs
> money and more checks and frequent  adjustments cost money too.[
>
> Generally Cosina lenses are very good  and surpass many of the older
> Leica designs. That is the power of modern computer programs and
> improved manufacturing technology.
>
> An intriguing question is this: do Cosina lenses show significant
> differences when stopped down to Leica lenses stopped down to the same
> aperture.
>
> My simple answer is yes.
> The advantages of Leica lenses are its tighter tolerances, use of better
> quality glass, advanced optimization and this shows at all apertures in
> higher micro contrast, higher transparency (finer reproduction in high
> lights and shadow areas), lower level of residuals (finer
> differentiation of hues and tones in small details), greater fidelity of
> reproduction etc. All of this over the entire (or most of it) picture
> area.
> There is a diminishing return of course and at f/11 it would be quite
> difficult to see the difference.
> Here one has to insert a few caveats.
> If the photographer is not sensitive to subtle differences and does not
> do his own careful comparisons, these aspects may escape him/her. Listen
> to an orchestra conducted by two different directors playing the same
> piece of music!. Some will here the differences immediately and some
> will not. A trained&nbsp;ear is needed. So is a trained eye.
> If the photographer's technique is sloppy or careless or if the material
> used is not up to the demands of the lens, many differences will be
> washed away by the generally very high noise level of the imaging chain.
> My view is this: the Cosina lenses deliver amazingly good image quality
> and many users will be served very well by this range of lenses, which
> expands at a remarkable speed.
> Generally they offer better imagery than many Leica lenses of the
> previous generation. Any one who raves about his Summicron DR should try
> the Nokton 1.5/50 and get an insight in optical progress made possible
> by current
> design programs and optical theory.
> Current Leica designs have a clear edge
> and you can appreciate that if you are willing to invest some time in
> the study of their characteristics: It is easy to gulp down a glass of
> superb wine and not note the difference in taste when compared to a
> cheaper wine. As
> any wine lover will tell you: take your time and chew!
>
>