Lens Quality

[justjack]

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Are there any know significant differences in manufacturing quality of lenses before and after 1950?

[jerzy]

there are 2 factors: coating and introduction of lanthanium (rare earth) glass however I would not fix it to exactely 1950. Leica begun with coating in late fourties, lathanium glass I believe 1952-53

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[lars_bergquist]

I agree that you cannot fix a limiting year. In the 1930's Max Berek and his aides were designing lenses with the aid of slide rules, logarithmic tables, experience, lots of intuition and a pot of tea (Berek liked to work at night with his dog Hektor sleeping nearby). Glass was traditional crown and flint and surfaces were uncoated. Then a technical revolution started: Coating of course, making lenses with more than six air-glass surfaces practical, high-refracting glass, later anomalous-dispersion glass – but above all the computer. The 50mm Collapsible Summicron of 1953 was the first lens designed with computer assistance. This made it possible to rigorously compute what had previously been approximated by rule of thumb. In the late 1950's Leica lenses became impervious to UV light by a combination of controlled coating and absorbing lens cement.

 

All that happened gradually. Computer software was improved in-house, experience was gained. It took until the late 1970's in fact until the designers learned to produce really good retrofocus wide angle lenses. Then followed the aspherical revolution, while computer-assisted manufacturing produced mounts with an unheard-of degree of precision.

 

Therefore you have to consider the individual lens design. To understand that you have to learn to understand a little bit of optical theory, and how to interprete MTF graphs. But the data have been published, by Leica, by Erwin Puts and others.

 

The old man from the Age of Max Berek

[k_g_wolf ✝]

It is ALWAYS a joy to read your comments, Lars. Thx for all these detailed insights, they are

much appreciated.

 

Sometimes it appears, that you were at times positioned next to Barnack ... Ever thought of writing a book ??

 

 

 

Best

GEORG

[justjack]

I agree that you cannot fix a limiting year. In the 1930's Max Berek and his aides were designing lenses with the aid of slide rules, logarithmic tables, experience, lots of intuition and

 

Thanks for the prompt and very detailed response. What I'm trying to determine is the desirability among collectors of a given lens design produced before or after the war. is it mainly about production numbers and rarity, age or something else? I understand the advantage of coated lenses for actual shooting but do collectors put a premium on uncoated lenses? I also thought there may have been problems with quality during the last few years of the war and several years afterwards while the country was rebuilding.

[luigi bertolotti]

Welcome to the forum !!!

You ask about MANUFACTURING quality, so I suppose you refer not to the optical performances, but to the precision / tolerancing / robustness of the optical/mechanical assembly : in this sense, one has to consider that this process has been not too different around the years you quote : a completely hand made series of operations, carried on by very skilled and well trained workers, with a very strict quality control on the final product and, surely, also in some intermediate phases.

So, the considerations that can be made are :

- In the pre-WWII times, Leitz was a well organized and wealthy factory, with QC tools that probably were the best available at those times.

- In the first years after WWII, let'say 46-52 about, Germany suffered obviously of lack of well trained workers, and precision QC instruments were probably scarce, with their manufacturers suffering the same issue of Leitz.

- Lenses production grew from (round) 10K units in 1945 to a peak of 65K in 1952, then continuing in the 30-40K area, in a period in which Leitz (with M3 intro in 1954) re-established its leadership.

- So, considering the above figures, they had to manage a ramp-up in production before the , let'say, "golden age" of German industry, a time in which they had a rather stable output of lenses within a company that was earning good money, and with the availabilty of well-trained workers and a new breed of excellent QC instruments: an ideal situation to pursue a continuous quality improvement, having managed in the previous years the organizational issues of high volume production.

 

At the end, having personally lot of Leitz lenses, aged from any year between 1947 and '60s (my first "hole" is 1969...) I'm not surprised to observe that lenses of, say, 1955 to 1965, have a TOP manufacturing quality in any detail... while the items, say, 1947-1952 do show a quality level someway lower... but, remember, always from a Company in which QC has always been more than a common term for manufacturing process, but a top principle on which they built their market and name.

Edited December 17, 2011 by luigi bertolotti

[lars_bergquist]

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Thanks for the prompt and very detailed response. What I'm trying to determine is the desirability among collectors of a given lens design produced before or after the war. is it mainly about production numbers and rarity, age or something else? I understand the advantage of coated lenses for actual shooting but do collectors put a premium on uncoated lenses? I also thought there may have been problems with quality during the last few years of the war and several years afterwards while the country was rebuilding.

 

Collector interest and value is not primarily determined by optical quality ot usefulness (that was what I was discussing) by by rarity. It doesn't matter if the lens was a dog, if it is one of 48 in black paint instead of chrome, it's valuable! It is simply an odd variety of stamp collecting.

 

My own interest in old photographic equipment, and Leica gear in particular, is not of the philatelic kind, but the interest of a historian of technology. To me, a piece of equipment is fascinating if it is technologically significant – the first in a long line, or representative of its age.

 

Ye olde manne from the Age of the Box Camera

[jc_braconi]

. is not of the philatelic kind, but the interest of a historian of technology To me, a piece of equipment is fascinating if it is technologically significant – the first in a long line, or representative of its age.

 

Ye olde manne from the Age of the Box Camera

 

Same for me Lars

Thank you to give me the opportunity to tell it.

[luigi bertolotti]

+ 1

[iphoenix]

+2

[Washington]

yeah, me too.