[Leica] design 2

[Erwin Puts <imxputs@ision.nl>]

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 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!