Archived posting to the Leica Users Group, 2008/03/25

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Subject: [Leica] Another ZM lens on the horizon
From: freakscene at (Marty Deveney)
Date: Tue Mar 25 05:39:52 2008

Let’s not forget that Zeiss has a long history of out-sourcing lens 
manufacture and components.  Voigtl?nder, Bausch & Lomb, Ross, Koristka, 
Krauss, Kodak and Schneider Kreuznak have all made lenses and lens 
components for Zeiss.  Cosina is just the latest in a long line.  There is a 
weird, beautiful circularity about Voigtl?nder having made lenses for Zeiss, 
having their name bought by Cosina and then Cosina making lenses for Zeiss.

One of the things I admire about Leica is that they are good at coming up 
with their own designs.  Optical design is obviously their forte and they 
are great at it.  So are Zeiss, even if they achieve the end result in a 
different way. 

There are a couple of things that make these Cosina-Zeiss lenses 
particularly interesting to me.  One is that they are modern interpretations 
by Zeiss of their own classic designs.  Biogons aint Biogons, in that while 
the basic design may be similar, these new lenses are carefully considered 
modern iterations of those classics.  For instance, this 35/2.8 differs 
considerably from the classic Biogons (such as the 35/2.8 for the Contax 
rangefinders) in that it is a semi-retrofocus design and has obviously been 
completely recomputed.  Why it isn’t called a Distagon I can’t 
say, but it isn’t.  It’s a semi-retrofocus Biogon, because Zeiss 
says so.  I’ll take their word for it. The design philosophy of the 
Cosina Zeiss lenses is different to the lenses that Cosina design for 
themselves (and sell as Voigtl?nder – see now why I’m 
confused?); the out of focus rendition is better and there is a more 
consistent familial look between focal lengths in the Zeiss lenses.  In 
general, Zeiss use a relatively large number of spherical elements to 
achieve the end result.  Each lens element contributes a small amount, 
meaning they can mostly be made from glass types that are not partiocularly 
exotic, expensive or heavy.  They can have have excellent optical 
performance without collimation of each element being ultra-critical.  They 
can do this because their coating technology is so good and because many of 
the lenses are of specifications that are not pushing the envelope.  

Some specific aspects of construction are also different between Cosina made 
Zeiss and Voigtl?nder lenses – this becomes apparent on taking each 
apart.  Mainly there is more care put into making sure that the Zeiss 
labelled ones hold their elements in the right place.

The Zeiss labelled lenses resist flare better, because Zeiss have licensed 
their T* coating to Cosina for these lenses.  Cosina have their own glass 
making factory  and probably have also been licensed to make some 
proprietary Zeiss glass types for these lenses.  That cannot do anything but 
help optical performance.  The closure by Leica of their glass making and 
research plant was possibly one of the poorer decisions Leica have made 
– it seems to have resulted in the death of the 75 Summilux and the 
possible future death of the Noctilux.  It's hard to get a third party to 
make glass for you with cool times that are measured in decades (or even 
several years).  

These Cosina made Zeiss lenses are, for the most part, optically superior to 
both the Zeiss and Kyocera made ones for the Contax SLRs.  They benefit from 
an additional 25+ years of optical design, glass and coating technology.  
They benefit from an additional 30-40+ years of those things over the 
Contarex lenses.  My German-made Zeiss AE lenses for my Aria were not 
particularly mechanically good (particularly my sample of the 50/1.4, which 
had quite a bit of play in the front optical cell) and while the Kyocera MM 
made ones were definitely more lightly constructed and featured more 
plastic, they were optically better.  A lot of this was probably connected 
to the introduction of new lens designs or redesigns around the time the 
location of manufacture changed. 

Discussions about Zeiss always conjurs up the Contarex.  The Contarex stuff 
is mightily impressive, but not necessarily to the benefit of the user.  30+ 
years of glass and coating development has made a lot of difference to 
optical capabilities.  Any camera lenses that are as difficult to service as 
are the Contarex lenses are not the ‘ultimate’ lenses.  Anyone 
who has patiently heated a Contarex lens barrel to make it let go of a 
seated element or tried for hours to remove a seating ring without wrench 
slots would probably concur, without even mentioning focus problems caused 
by the lack of space to shim lenses for proper infinity focus.  It’s 
also unlikely that these lenses are cemented with resins which will separate 
as readily as the Contarex ones do or that the lubricants will be 
disastrously short lived.  That's without even looking at the bodies.  The 
factory workers who made the Contarex black finish on brass by dipping the 
machined components into molten cyanide salts would probably agree that 
modern black finishes are better too. 

I’ve used borrowed individuals of the Cosina made ZM 25/2.8, 35/2 and 
50/2 and several of the SLR lenses.  They’re all spectacular.  I am 
sure that the ZM 15 and 85 are stupendous, but I haven’t used them.  I 
don’t know anyone who has one that I can borrow either. If we’re 
talking about performance alone, the Cosina made lenses are arguably the 
optically best 35mm format ‘Zeiss’ lenses ever made.  It still 
doesn’t really make them ‘Zeiss’ lenses, but their optical 
qualities and the photos they give are remarkably good.  What you or I think 
of them relative to Leica lenses is more a matter of taste than objective 
quality, since both are so good you’re unlikely to see any serious 
optical flaws become apparent in pictures taken with either brand.  Our 
Leicas aren’t all Leica either.  Hoya is good enough for Leica to get 
some of the blanks for some of their lens elements from them.

Zeiss is Neiss and I like Leica, by whoever and wherever they're made.  
It’s the pictures that count.  



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Replies: Reply from at (Douglas Sharp) ([Leica] Another ZM lens on the horizon)
Reply from hoppyman at (Geoff Hopkinson) ([Leica] Another ZM lens on the horizon)
Reply from marcsmall at (Marc James Small) ([Leica] Another ZM lens on the horizon)