By José Manuel Serrano Esparza
In 1966 Leica launched into market the Noctilux-M 50 mm f/1.2 Asph, the first aspherical lens in history, designed by Helmut Marx and Paul Sindel, and whose first prototypes were made in April of 1964.
Top view of the Noctilux-M 50 mm f/1.2 Asph, showing its superb 12503 entirely metallic shade with double-trigger release and the 16 blade lens diaphragm making possible to get great portraits at widest f/1.2 aperture.
Featuring 6 elements in 4 groups, a 16 blade diaphragm, length x diameter of 60 x 61 cm, manufactured in black anodized aluminium exterior with bronze and stainless-steel inner area, and including two aspherical surfaces, its appearance aroused great expectation and undoubtedly meant a turning point in the history of photographic lenses, two years before Nikon created in 1968 its 9 elements in 6 groups OP Fisheye-Nikkor 10 mm f/5.6 with aspherical front lens element and five years prior to the presentation by Canon in 1971 of its 8 elements in 6 groups and 8 diaphragm blade Canon FD 55 mm f/1.2 AL, incorporating an aspherical element (which would be improved in March 1975 with the Canon FD 55 mm f/1.2 S.S.C aspherical, essentially the same lens but boasting multicoating).
The Noctilux-M 50 mm f/1.2 Asph meant to practical effects the fourth defining moment in the evolution of photographic lenses for 24 x 36 mm format, after the design of the Leitz Elmar 5 cm f/3.5 by Professor Max Berek in 1930, the Carl Zeiss Jena Sonnar 5 cm f/1.5 by Ludwig Bertele in 1932, and the Summicron-M 50 mm f/2 first version in 1953 designed by Helmut Marx.
Highly probably, this was the most strenuous lens to create ever along with the aforementioned Bertele´s CZJ Sonnar 5 cm f/1.5 (for which the genius born in Munich needed a total of roughly one million sheets of paper and a raft of manual calculi, because there weren´t any computers or software for optical design whatsoever), since it was designed and manufactured with utterly manual parameters, working without any CNC controlled grinding and polishing machines (so getting a centering of lenses to the highest accuracy became something of extreme difficulty) or computer and laser controlled instruments for an accurate interferometric examination of aspherical lenses to check their deviations, edge drop-off, astigmatic errors, etc.
To design and manufacture this lens was a huge challenge for Leica, because the need to generate exceedingly tiny deviations of microns in the original spherical lens surfaces to turn them into aspherical ones was virtually impossible to attain within stringent tolerances, since the production of aspherical lens surfaces was then something particularly complex, and frequently an optical element had to go through every step of the polishing and grinding method once and again and new testing methods had to be developed to achieve the technically huge precision needed for the manufacture of the aspherical surfaces of the elements.
Detail of the scalloped focusing ring of the Noctilux-M 50 mm f/1.2 Asph, whose mechanical construction is exceptional.
In addition, any attempt of mass production became a virtually impossible task, particularly during the assembly period, because the state-of-the-art technology needed for assuring the fulfillment of the narrow tolerances and accuracy for grinding and polishing the aspherical surfaces wasn´t available at the time, so only Helmut Marx and Paul Sindel could do it in an entirely handcrafted way.
Needless to say that because of all those factors, the hugely time consuming only way to do things and a very high quantity of rejected optical elements, production cost skyrocketed, since vast majority of stages could only be accomplished with great slog by a very small number of highly qualified and experienced persons.
THE SUBJECT OF THE PERFORMANCE OF THE NOCTILUX-M 50 MM F1.2 ASPH LENS
To begin with, putting this lens through its paces has never been an easy job, because it is a rare objective ( only 2,450 units were made between 1966 and 1975) reaching very steep price tags in either auctions or private transactions among collectors, investors, etc, so having the chance of properly make tests with one of them can be risky if any little scratch, dent or cleaning mark could be produced during its use, resulting in a drop of its selling worth, since it is evidently a legendary lens and samples in A/B or near mint condition can fetch exorbitant prices.
Moreover, if the sample to test has been unused for a long time, chances are that it will need a CLA.
Therefore, the Noctilux-M 50 mm f/1.2 Asph inherent nature as a coveted item for both discerning collectors and investors has meant that only a very reduced group of professional photographers have had the opportunity to get pictures with it coupled to Leica M bodies in real photographic contexts.
And regarding results in optical performance, though most of those knowledgeable testers have defined the lens between very good and excellent, there have been sometimes certain differences among the samples.
The lens exhibits very good resolving power, sharpness and contrast at f/1.2 in the center of the image for such a huge aperture for the time, with a drop to acceptable in borders and corners, while on stopping it down to f/1.4 and f/2 there is a major improvement in acutance, thanks to an excellent contrast on the whole of the image surface, whose qualitative level will significantly increase on stopping down to f/2.8 and f/4 and will reach its peak values at f/5.6 and f/8, where optical performance of the lens can be bluntly defined as extraordinary.
As has often been explained by the world-class expert on photographic lenses Erwin Putts, there was the rumor throughout decades that the Noctilux-M 50 mm f/1.2 Asph delivered its best image quality at f/1.2 and it decreased on stopping down, what proved to be false, since the lens yields a very good optical performance at widest f/1.2 aperture but obviously improves on stopping down.
But it isn´t less true that there have been some testers stating that the non aspherical Noctilux-M 50 mm f/1 gives better results at its widest aperture f/1 than the Noctilux-M 50 mm f/1.2 Asph at its widest f/1.2, which is not true in vast majority of the latter´s produced units, specially in contrast and color rendition, where the Noctilux-M 50 mm f/1.2 Asph is superior.
Lateral right view of the Noctilux-M 50 mm f/1.2 Asph showing the gorgeous brass helical focusing mount, manufactured in the Lathe Department at Leitz Wetzlar, where were made all the round mechanical components like setting rings, tubes, mounts and helical focusing mounts for lenses.
© Leica Camera AG
What can be the origin of the occasional differences in test results with this mythical lens?
Evidence suggests that it greatly stems from the extreme difficulty to get a uniformity of performance unit by unit within each batch of the very low figure of Noctilux-M 50 mm f/1.2 Asph manufactured , because of the previously mentioned completely manual method for designing and manufacturing.
Anyway, the great optical performance delivered by this lens, even at full f/1.2 aperture, straightforwardly indicates that Leica was in mid sixties far ahead of the Japanese brands of photographic industry in the optical design of ultraluminous lenses.
© Leica Camera AG
And this is something really praiseworthy, because the wherewithal of its own and resources of the relatively small German photographic firm was far from the immense potential in both cash-flow and R & D of the great Japanese corporations that had held sway over the photographic market since early sixties with their excellent 24 x 36 mm format reflex cameras featuring virtually unbeatable price/quality ratio, and also had great optical designers at the time like Kakuya Sunayama, Saburo Murakami, Hideo Azuma, Zenji Wakimoto, Yoshihada Hayamizu, Toshihiro Imai, Nobuo Yamashita, Toru Fujii, Hiroshi Takase, Yoshiaki Horikawa, Tadashi Kimura, Fumitaka Watanabe and others.
But Helmut Marx (Professor Max Berek´s successor as head of the photographic lens design office of Ernst Leitz factory in Wetzlar and creator of the Summicron 50 mm f/2 1st version in 1953) was then the best optical designer in the world along with Walter Mandler (at the Ernst Leitz Canada factory in Midland, Ontario), and with the lenses designed by them for Leica M cameras, new standards in optical performance were set.
And amazingly, the Noctilux-M 50 mm f/1.2 Asph was launched into market by Leica in 1966 as a production series item, some years before Professor Helmut Marx began to develop his COMO optimization program for lens designing with the help of special computers in late sixties, including all the opto-mechanical data regarding the construction of a top-notch performance lens, saving a lot of years of work.
Back left view of the Noctilux-M 50 mm f/1.2 showing once more the fabulous mechanic construction of the lens visible in the brass helical focusing mount and its aluminium area, and the rest of the exterior metallic surfaces manufactured with black anodized aluminum, while the inner metallic components are made with bronze and stainless steel to ensure a smooth operation.
© Leica Camera AG
Whatever it may be, there were tons of intuition, expertise and optical insight in the design of the Noctilux-M 50 mm f/1.2 Asph by Helmut Marx and Paul Sindel, without forgetting the accuracy and toil of Gerd Bergmann using a just created Leitz developed early copy grinding machine to machine produce aspherical lens surfaces with remarkable precision, something that only he could do.
But coming back to the topic of the alleged superiority in image quality of the fabulous non aspherical Noctilux-M 50 mm f/1 at widest aperture over the Noctilux-M 50 mm f/1.2 Asph at widest f/1.2 aperture, reported by some testers, sincerely, I don´t think so in vast majority of the 2,450 units made of the Noctilux-M 50 mm f/1.2 Asph, because at the moment in which Leica launched into market this first aspherical lens ever in 1966, the German photographic firm needed to show its optical prowess before the unstoppable advance of the Japanese photographic industry from early sixties, and top priority was to get an ultraluminous first-class 50 mm f/1.2 standard lens, whose performance at widest aperture in the center wasn´t simply acceptable but really very good and professional in terms of resolving power, sharpness, contrast and color rendition.
Particularly the yielding of excellent contrast was very important, because from early fifties Nikon had launched into market highly luminous standard lenses like the Nikkor-S.C 5 cm f/1.4 delivering great image quality in the center and superb contrast, whose mission was to optimize the acutance and visual feeling of sharpness of the images in symbiosis with excellent coatings, so when the pictures made with them were reproduced in the illustrated magazines of the time, they often seemed sharper than better German lenses from Leica and Carl Zeiss yielding more resolving power but not as good contrast, as happened during the Korean War with Nikkor lenses used on LTM39 mount Leica (David Douglas Duncan, Miki Jun) and bayonet Contax (Horace Bristol, Carl Mydans, Margaret Bourke-White) 24 x 36 mm format rangefinder cameras.
Optical scheme of the Noctilux-M 50 mm f/1.2 Asph, featuring 6 elements in 4 groups and a diaphragm with 16 blades, enabling it to get very beautiful bokeh and portraits at widest f/1.2 aperture. The two aspherical surfaces (one in the front element and another in the rear one) featured by the Noctilux-M 50 mm f/1.2 Asph meant a pivotal instant not only in the history of Leica but also in the sphere of photographic lenses broadly speaking, since it paved the way for significantly reducing the dimensions, weight and number of elements and groups of ultraluminous lenses in comparison to spherical designs featuring larger size, weight and more elements. In addition, aspherical lens surfaces started to stand out in mid sixties as a very efficient way to reduce optical aberrations, so their mileage in these regards would become a future trend and mainstay in the German firm assortment of highly luminous lenses from 1990 onwards, when new technologies of precision molding (used for wideangle lenses) and CNC controlled grinding and polishing machines (optimized for standard 50 mm and longer lenses) enabled to manufacture aspherical lens surfaces with a much higher degree of precision.
© Leica Camera AG
Therefore, the Noctilux-M 50 mm f/1.2 Asph was an all-out effort made by Leica to prove its leading-class position in the scope of the design of highly luminous lenses, with an optical performance at widest aperture that was utterly professional in terms of image quality and with which it managed to significantly up the ante in 1966, after having dabbled into aspherical lens surfaces production for the first time nine years before, in 1957.
Obviously, the 7 elements in 6 groups and 10 diaphragm blades Noctilux-M 50 mm f/1 from 1976, designed by the optical wizard Walter Mandler, is a stratospheric level lens even to current standards, but the approach was different : fully aware that the production cost of the Noctilux-M 50 mm f/1.2 Asph was huge and virtually impossible to implement a rational manufacturing program and uniformity of imagery performance in each lens of every batch, he designed a non aspherical and extraordinary 50 mm f/1 lens featuring one more element than the aspherical pioneer, with three main goals : to reduce the production cost, to ease the series production and to get splendid image quality from f/1.4 onward and a unique aesthetics of image at widest f/1 aperture, with a wonderful bokeh.
Id est, Mandler´s design was mainly based on a cost effective philosophy through which the lens had to yield excellent optical performance between f/1.4 and f/8 and a usable image quality at widest f/1 in terms of resolving power, sharpness and contrast, but enhanced by an exceptional bokeh in the out of focus areas, with a really unique look.
On the other hand, Leica had a much more solid economic position in mid sixties, when it launched into market the Noctilux-M 50 mm f/1.2 Asph, than in 1976 when it introduced the non aspherical Noctilux-M 50 mm f/1, to such an extent that in mid seventies, the German photographic firm was fighting for its survival, particularly focused on the preservation of the Leica M lineage of cameras and lenses, which was about to disappear and only the tremendous insight and product knowledge of Walter Kluck (President of Ernst Leitz Canada factory in Midland, Ontario, who after the failure of sales of the Leica M5, convinced the Leitz Wetzlar management to renew the Leica M breed with a further production of 4.000 new cameras, and was able to get 9,000 orders, until the new Leica M4-2 was announced at Photokina 1976, the same year in which the Noctilux-M 50 mm f/1 was presented).
On its turn, the Noctilux M 50 mm f/1.2 Asph appeared in 1966, with an instantly accomplished aim: to become the best ultraluminous standard lens in the world at widest aperture, and top goals were maximum feasible resolving power, sharpness, contrast and excellent colours at f/1.2, with a truly professional image quality, and extraordinary optical performance on stopping down from f/1.4, almost on a par with Mandler´s Summilux-M 50 1.4 from 1959.
This lens was for Leica what the 7 elements in 6 groups Noct-Nikkor 58 mm f/1.2 Asph featuring a hand ground aspherical surface on the front surface of the forward element would be for Nikon in 1977, id est, the jewel of the crown of the firm´s lineup of lenses.
Walter Mandler knew perfectly that designing a Noctilux-M 50 mm f/1 with extraordinary resolving power, sharpness and contrast at such hugely wide aperture with aspherical lenses would have meant a tremendous production cost for Leica, including the use of highly exotic and expensive optical glasses, so he decided to generate a dual purpose excellent lens featuring two main virtues:
a) An acceptable optical performance at f/1, not specially great in sharpness and contrast, with incredibly shallow depth of field, but with a top priority aim : a unique swirling bokeh wonderfully yielding the out of focus areas with an amazing impressionistic look and painterly quality, fruit of the wisely chosen degree of different optical aberrations preserved by Mandler to achieve that visual effect at the widest aperture, more typical of some old large format lenses.
This way, photographers could leverage the short tele lens nature inherent to the 50 mm focal length in both portraits and pictures in which they desired to enhance the persons or objects in the foreground.
b) A very good optical performance at f/1.4 and excellent from f/2 onward, using the lens as a normal standard 50 mm objective.
This way, the Noctilux-M 50 mm f/1.2 Asph was the Leica benchmark in optical performance as to resolving power, sharpness, contrast and colors at widest aperture among its ultraluminous f/1 and f/1.2 standard lenses for forty-two years, between 1966 and 2008, when the Noctilux-M 50 mm f/0.95 ASPH, designed under the supervision of Peter Karbe, was introduced.
THE FASCINATING EVOLUTIVE TRUTH ON THE NOCTILUX-M 50 MM F1.2 ASPH UNVEILED DURING THE LEICA HISTORICA e.V MEETING OF OCTOBER 2018 INSIDE THE ARCONA LIVING ERNST LEITZ HOTEL IN WETZLAR
© Paul Robert
Dr. Wolfgang Vollrath (former Head of Optical Design at Leitz Wetzlar between 1981 and 1990 and creator of some world-class Leica lenses like the Apo-Macro-Elmarit-R 100 mm f/2.8) imparted on October 14, 2018 inside the Arcona Living Ernst Leitz Hotel in Wetzlar, as part of the programm of the Annual Meeting of the Leica Historica e.V, a landmark lecture titled " How it all Began : Leica Lenses with Aspherical Lenses, New and Unprecedented " , which elaborated on a lot of greatly unknown and very interesting aspects related to the pioneering aspherical lenses manufactured by Leica, as well as proving that the Noctilux-M 50 mm f/1.2 Asph lens designed by Helmut Marx and Paul Sindel was the fruit of nine years of previous toilsome groundwork from 1957 and the evolutive pinnacle of a breed which however incredible it may be was born in late fifties with two impressive aspherical prototypes for the time:
© Paul Robert
a) The Summaron-M 35 mm f/2.8 Asph prototype from 1958, featuring 2 aspherical surfaces, designed by Helmut Marx through the symbiosis between his tremendous optical knowledge and intuition and the help of an Elliott 402F computer controlled by a magnetic drum with 4,000 32-bit words and being 150 times faster than the previous Zuse Z5 with profusion of electromechanical relays (which had already accelerated lens design at Leitz almost seventy times over manual calculations), significantly saving manual time consuming ray tracing during the design stage and enabling to fulfill a better correction of errors in sagittal areas.
© Paul Robert
Dr. Wolfgang Vollrath explained that Helmut Marx (who was then incepting the embryo stage of what would result in his famous COMO program for lens designing optimization) took the decision of using aspherical surfaces in 1958 to improve the performance of the Summaron-M 35 mm f/2.8 Asph prototype (which was very advanced in 1959 but wasn´t finally produced in series) after a lot of conversations with Walter Mandler.
© Paul Robert
b) The six elements Noctilux-M 52 mm f/1 Asph prototype, featuring 2 aspherical surfaces and designed by Helmut Marx and Paul Sindel in 1959, whose aim was to beat the optical performance of the non aspherical 7 elements in 5 groups and 11 diaphragm blades Canon 50 mm f/1.2, designed by Ito Hiroshi in April of 1956, a very good ultraluminous lens for the Japanese brand cameras sporting M39 mount, with a Planar design and whose selling price Canon had managed to reduce to half in 1957, streamlining production stages, in addition to having been extensively used by David Douglas Duncan in his essays on Pablo Picasso.
Helmut Marx and Paul Sindel knew that though being a very good lens, the performance of the Canon 50 mm f/1.2 at widest aperture was poor in terms of resolving power, sharpness and contrast, because the Japanese firm had to sacrifice a certain degree of performance to be able to achieve such a huge maximum diaphragm, so Ito Hiroshi had decided to optimize the f/1.2 aperture to get beautiful portraits with soft and center emphasized images.
© Paul Robert
Anyway, Helmut Max and Paul Sindel were not able to achieve the great image quality at widest aperture they wanted with the Noctilux-M 52 mm f/1 Asph prototype from 1959 (which didn´t go into series production either) and realized that the only way to achieve it was with a maximum aperture of f/1.2.
© Paul Robert
On the other hand, both optical designers felt that the evaluation of the only prototype sample of the Summaron-M 35 mm f/2.8 Asph from 1958 was being very expensive and the advances in optical performance in comparison with the non aspherical 35 mm f/2.8 Leica lenses already in existence were very small and didn´t match the expectations of the optical calculi, so after a thorough mesurement inside the Leitz laboratory of optical tests in Wetzlar, it was discovered that because of the prolongued polishing times, the out of tolerances variations of the forward aspherical elements were much bigger than in the rear ones.
© Paul Robert
That´s why the front optical elements were even more painstakingly manufactured again and measured after the polishing and grinding,
© Paul Robert
which resulted in a major improvement of the performance of four new Summaron-M 35 mm f/2.8 Asph prototype lenses with 2 aspherical surfaces made in 1960.
But the production cost had been enormous, with a 75% of rejected prototype samples from a total of sixteen manufactured, id est, twelve of them whose attained image quality had been between moderate and bad.
The upshot of it is that stunningly, from mid fifties, roughly two years after the launching into market of the Summicron-M 50 mm f/2 Dual Range in 1956, Leica was already trying to create with unbridled enthusiasm a stratospheric for the time Summaron 35 mm f/2.8 Asph wideangle lens boasting 2 aspherical surfaces and delivering excellent image quality at its widest aperture.
This clearly suggest that Leica top brass was fully aware in late fifties that 35 mm wideange highly luminous lenses would soon replace the 50 mm standard lenses (that had reigned supreme since mid twenties) as favourite lens among professional photojournalists, and aside from the non aspherical Summarons 35 mm f/2.8 and Summicrons 35 mm f/2 from 1958, they strove upon creating a Summaron-M 35 mm f/2.8 Asph with two aspherical surfaces yielding an even better optical performance, but it wasn´t impossible to implement a series production with the technology and manufacturing methods available then.
Anyway, Helmut Marx and Paul Sindel dind´t surrender, rose to the challenge and the great know-how they had acquired designing the prototypes of the Summaron-M 35 mm f/2.8 Asph, limping along with strenuous personal effort, suffering and sweating, would pay off in very few years.
As a matter of fact, in 1962 a German photographer called Mr Seck got pictures in both different streets of Frankfurt and some circuses with a Leica M camera coupled to a prototype of a 6 elements Noctilux-M 52 mm f/1.2 Asph featuring two aspherical lenses (made by Leitz optical designers Brück and Hoffmann, following Helmut Marx´s instructions) obtaining very good results, but simultaneously, the huge production cost, very time consuming manufacturing method, exceedingly complex new ways of testing, very high rate of rejected optical elements out of tolerances, etc, kept on turning the series production into something out of the question.
© Paul Robert
But through perseverence and very hard work, improvements went on being made until the Photokina of 1966, when after a two year stage of prototypes, the Noctilux-M 50 mm f/1.2 Asph with 2 aspherical surfaces was introduced by Leica as a series production item, with detailed previous information on the lens provided by the publicity department headed by Mr Jaeckel and a lot of tests made with some lenses attached to Leica M cameras by professional photojournalists like Bob Schwalberg.
Though being a tremendous optomechanical revolution for the time and an accomplished tour de force, Helmut Marx realized that a strong vignetting of 3.5 diaphragms in the corners at widest f/1.2 aperture couldn´t be avoided.
This is a highly significant aspect, because Professor Helmut Marx, a true visionary in the scope of photographic optics, had clearly perceived from mid sixties that the extraordinary four-part Leica M bayonet (exceedingly sturdy, with a diameter of 44 mm and a flange distance of 27.8 mm) designed by Hugo Wehrenfenning in February of 1950 and whose shape was optimized to make possible that the maximum amount of light coming from the optical system of the lens could reach the outermost corners of the image) was too small to get rid of big levels of falloff on the corners with lenses featuring f/1 and f/1.2 huge widest apertures.
That´s to say, Helmut Marx had envisaged with almost fifty years of anticipation the need to build larger mounts with shorter flange distances to fully synergyze with f/1 and f/1.2 lenses to reduce vignetting at full aperture as much as possible, something that would result in the inception of the Leica L-Mount bayonet (featuring a diameter of 51.6 mm and a flange distance of 20 mm) introduced in April of 2014 with the excellent APS-C format Leica T as a starting technological platform for the development of the formidable 24 x 36 mm format mirrorless Leica SL System of digital cameras and telecentric lenses which would appear in October of 2015.
This historical lecture imparted by Dr.Wolfgang Vollrath also showed that after the launching into market of the Noctilux-M 50 mm f/1.2 Asph, Helmut Marx didn´t rest on his laurels, got up steam and tried along with his collaborator Mr Desch to design a Noctilux-M 50 mm f/1 Asph, with three main possible routes to attain it:
© Paul Robert
a) An additional hollow aspherical surface (in symbiosis with the two ones already existing) behind the diaphragm, though practice proved it wasn´t feasible, so an alternative solution was devised applying an aspheric surface to the convex surface of the meniscus.
© Paul Robert
b) The introduction of lateral lenses invented by Helmut Marx, creating an optical element made up by spherical annular lenses featuring different curved radii and kinds of glasses.
Those annular lenses would only work in the diaphragm sector between f/1 and f/1.2, on the image center, and because of the strong vignetting, they wouldn´t have any effect on the image field.
© Paul Robert
c) An idea provided by Walter Mandler: an aspherical flat disc inside the diaphram space.
All of these concepts were put into practice until 1970, trying to design a Noctilux-M 50 mm f/1 Asph with three aspherical surfaces, but the project was abandoned, because the technology of aspherical surfaces was in its infancy, the production costs kept on inevitably being very expensive, the measuring tools were still immature and a homogeneity of optical performance unit by unit within each batch for series production was virtually unfeasible for the time being.
Noctilux-M 50 mm f/1.2 Asph beside a picture of Professor Helmut Marx, its main designer.
But whatever it may be, the design and manufacture of the legendary Noctilux-M 50 mm f/1.2 Asph, launched into market in 1966, has undoubtedly been one of the greatest feats in the history of photographic lenses, proving Leica unflinching level of commitment with its worldwide customers and the indefatigable fighting spirit to get unrivalled optical excellence with its highly luminous and top-notch quality lenses, which has always been a significant part of the German photographic firm hallmark, including its pioneering spirit on starting the design and manufacture of aspherical lenses in 1957.
The author wishes to express his gratitude to the Dutch photojournalist and travel writer Paul Robert, who had the kindness of getting the pictures of Dr.Wolfgang Vollrath´s milestone lecture in Wetzlar.
On the other hand, obviously there is a myriad of aspects of all kind in the design and development of this legendary lens that go far beyond my very limited knowledge, so the only thing I could do was to fight trying to avoid errors.
I´m also thankful to Westlicht Vienna for having allowed me to get pictures of one unit of this lens.