Re: [Leica] leica selling inferior lenses out of the box?

[SthRosner@aol.com]

In a message dated 3/8/02 12:14:23 PM Eastern Standard Time, 
KCassidy@asc.upenn.edu writes:

> i take this to mean that there is a great variation in tolerence in new
>  leica lenses? 

No, Kyle, there is (was) a very narrow tolerance variation that is in fact 
narrower still today because of the even more accurate manufacturing 
machinery currently used. Erwin has referred to this in his writing, 
commenting that in the 1950s and 60s and perhaps later, experienced 
professionals used to try several examples of the lens they wanted to buy 
before deciding, on the basis of the photographs they made, which one pleased 
them most.

> "within spec" is apparantly wide enough anyway that by looking
>  at it an expert can tell the top of the heap from the bottom of the heap.

There is no Leica "bottom of the heap": that implies that there are junk 
Leica lenses which is simply not true. I think I once mentioned the following 
anecdote on the LUG: many years ago I lived in Paris and in 1961 bought a 
Super 90 Porsche at the factory. I raced this car at the Autodrome of 
Linas-Montlhery, south of Paris. For servicing I naturally took it to the 
Paris Porsche dealer. After the first service, his top mechanic said to me - 
"you got an exceptional car here. Every car that comes from Porsche is 
excellent but occasionally, one comes off the production line where all of 
the parts just seem to have fitted together with absolute perfection." 

There are tolerances in every manufactured product. Nothing is perfect, even 
that old Super 90 Porsche of mine. Porsche tolerances are extremely high 
(that is, narrow), compared with the large majority of auto manufacturers. 
Leica tolerances are extremely high (ditto), compared with EVERY camera and 
lens manufacturer today.
And I am certain that Erwin is correct in saying that they are high compared 
with Leitz tolerances 30 years ago. It explains why, when you look at a 50/2 
Rigid Summicron from the 50s or 60s you will see on the focussing mount to 
the right of the focussing scale a two digit number. Here is Erwin's 
explanation verbatim:

>>It is well known and this info can be found among many writers, for example 
Rogliatti: Leica and Leicaflex lenses (2nd edition), that the tolerances in 
the manufacturing process of lens elements (distances between elements, some 
difference in curvature of surfaces, different refractive indices per charge 
of glass melting etc) will generate some differences in the actual focal 
length of the lens. 

>>But we have first to estabish the calculated the true calculated optical 
focal length of a lens. For the Summicron 2/50 (second generation) this is 
52.02 and for the Summarit 1.5/50 it ois 52.16mm. 

>>It is well known and this info can be found among many writers, for example 
Rogliatti: Leica and Leicaflex lenses (2nd edition), that the tolerances in 
the manufacturing process of lens elements (distances between elements, some 
difference in curvature of surfaces, different refractive indices per charge 
of glass melting etc) will generate some differences in the actual focal 
length of the lens. 

>>But we have first to estabish the calculated the true calculated optical 
focal length of a lens. For the Summicron 2/50 (second generation) this is 
52.02 and for the Summarit 1.5/50 it ois 52.16mm. 

>>In the past the production process was not as accurate as it is today and a 
wider range of measured focal length could be found. 

>>The older Elmar 3.5/50 as example has been recorded as ranging from 48.6 to 
51.9mm in steps of about 0.3mm (not exactly. (Info from the book " 25 years 
Leica Historica" and the magazine of the Leica Historical Society UK). The 
newer Elmar 2.8/50 had only three groups: 51.6 and 51.9 and 52.2mm. 

>>The older Summicron has the same groups: 51.6 and 51.9 and 52.2: a 
difference in distance of 0.3mm.

>>The Summilux has these groups: 51.0 (indicated as (10),; 51.14 (11); 51.3 
(13); 51.45 (14); 51,6 (16); 51.75 (17); 51.9 (19); 52,05 (20) and 52,2 (22). 

Picking up Kyle's comment:

>  i've heard this is true with jupiter lenses, but how can someone such as
>  myself (not an expert in leica lenses) keep from getting a klunker when
>  buying brand new leitz glass? 

.......you shouldn't get a clunker, unless q.c. at Solms has let pass a 
subpar lens which can happen but only very, very rarely. 

>  you mention marty forscher "checked out" the lens was this with machines? 
or is >  there a cabbalistic secret where you can hold it up to the light and 
say "ooh, >  
>  spherical abbhoration!" 

I don't do physical tests of lenses. I believe that what Forscher, John Van 
Stelten et al. do is put a lens on an optical test bench. I do recall that 
what Marty was talking about on my Dual range was the fact that with the 
first one, on the test bench, flare disappeared rather later (i.e. at a 
smaller aperture) than might be found in another example. That was not a 
"flaw" or an indication that it was a clunker lens, simply that the enhanced 
contrast from the disappearance of flare came closer to f/4 than to f/2,8, as 
an example.

I am a nut on quality - in any product I buy and use. But Kyle's final 
question, understandable as it is,

>  finally, if one does buy a lens from the bottom of the pile,
>  has it checked out and it's found to be "not as good" will leitz replace 
the
>  lens, or are you stuck with it?

......is a misunderstanding of what I intended to say. There is no bottom of 
the pile in Leica equipment. I didn't intend to suggest that at all. If, in 
fact, a buyer gets a really bad lens - and I suppose that can happen - I 
believe Leica would replace it. In fact I have a vague recollection that our 
friend Tom Henson did buy such a lens and Leica did in fact replace it.

Sorry for the length of this response but Kyle's question is an important one 
and having caused it, in fairness to Leica, a full response was appropriate.

Seth        LaK 9
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