The credit for the invention of the Leica is always given to Oskar Barnack, and rightfully so. But it is doubtful that the camera would have been successful, had it not been for the incredibly well performing lens designed by Dr. Max Berek. Thus he deserves equal credit for the success of the early Leica cameras and lenses, which is exactly the reason why this blog gives credit not only to the Leica and Oskar Barnack but to Max Berek as well.
The following interview is historic in nature. I translated it from LEICA BREVIER, published in Wetzlar in 1949.
I have not been able to learn who the interviewer was, but Max Berek's answers are always interesting and often intriguing in light of technical developments of the intervening decades.
Max Berek
Q: Herr Professor, you designed the first Leitz lens. The Elmar 50/3.5 and later the Summitar 50/2.0. Both are referred to as “universal lenses.” Does that mean the Elmar has been surpassed by the Summitar?
MAX BEREK: I am glad you asked this question first. Even beginners in photography believe they can't get by anymore with a lens opening of less than f/2, to be prepared for all occasions.
But I want to get more detailed. When Leitz, after almost ten years of development, introduced the Leica in spring of 1924 (ed. Note: 1925), it didn't start with a lot of advertising, like most inventions, but it was humbling and exploring; it was to speak for itself when it came to prove its right for existence. It was perfectly clear to us that something so principally new and tradition-defying as this camera would only be accepted with the greatest reservations by most photographers; the manufacturer, though known worldwide in scientific circles for its microscopes, was totally unknown as a camera maker. Therefore we had to try to prevent the possibility of being discredited right at the beginning. And that meant especially the creation of a high quality lens.
Of course, we would have been in the position at the time to design a lens with an aperture of f/2, but the amateur possessed as much as no experience for the useful application of such a fast lens; they didn't know the pitfalls and the difficulties. So we gave the Leica, for well-considered reasons, a normal lens with a speed of f/3.5. For the time this was already unusually fast and still today it does justice to all tasks the amateur might ask of it for his pictures. Even he who has only little experience will agree with this and should know especially that the times when it is absolutely necessary to have a speed of f/2 are rare for the amateur.
If, however, as an experienced Leica photographer one often takes pictures under very unfavorable lighting conditions, like sports and vaudeville photographs, of course he wouldn't want to be without a fast lens.
One knows from his own experience the limits of large apertures, if for no other reason than the rather shallow depth of field and you shouldn't have the ambition to photograph everything under all circumstances wide open, just to save on exposure time. One also knows that most pictures by far are made at apertures of f/5.6 or f/8 and that therefore an aperture of f/3.5 presents a fine reserve for adverse lighting conditions. But even at full aperture the Elamr still has such a great depth of field that with halfway correct focusing one will always obtain good pictures and that is exactly what we wanted to achieve in the first years of Leica photography. Not until later did we change over to increasing apertures to f/2.5 and f/2 and lately f/1.5. This is still the path everybody should take and nothing would be more wrong than to start with wide apertures.
Max Berek's notes for the design of the 50mm f/3.5 Elmax,
the original lens of the Leica Model A or Leica 1
But the Elmar has another advantage: it is very robust, space saving and lightweight. Just think of a mountain climber – I don't mean the one going on walks in the mountains, but the real climber taking pictures in dangerous situations – he can't risk fighting the difficulties that the use of a fast lens will bring with it. For him the Elmar is invincible In my Alpine photography at the Matterhorn, at the Monte Rosa, etc. - these must be the first ones taken with a Leica – I only used the Elmar f/3.5 and still today these pictures will withstand any critique. The Elmar 50/3.5 will always be the recommended lens for the amateur.
Q: Yes, and how is it with color pictures? How do lenses behave there?
MAX BEREK: Well, as you know, color film is pretty much equally sensitive to all types of light of the visible spectrum. The condition, of course, is that the lens in use has favorable color correction over the entire visible spectrum. The old anastigmats, 30 to 50 years ago for instance, wouldn't be of much use because they were corrected for film materials that were mainly sensitive to green, blue and even purple. The correction in the red end of the spectrum was totally neglected at the time. The first Leica lens, however, already possessed a color correction over the entire visible spectrum.
One could say that the lens that fulfills the needs of panchromatic film will do so with color film. It is like this: black and white film will always show its density as a shade of black, whether or not it is caused by red, yellow or blue light. If the light will cause unsharpness, this will be registered by the film, regardless which light might have caused it.
Max Berek at his desk
With color film this is different. Then the red and the blue part of the spectrum will only be registered in proportion to the sensitivity of the eyes which are most sensitive to yellow. Therefore the spherical correction of a lens has to be especially good for the center part of the spectrum and that is something that was taken care of in Leica lenses in the very first examples.
In practical applications another point is even more important: the freedom from vignetting in a lens. Normally vignetting shouldn't influence the color correction since the combination of the light does not change. In practice, however, it will affect it anyway since color film has a comparatively narrow exposure latitude. If the lens shows rather strong vignetting, the corners of the picture will slip very soon into the region of underexposure and will show wrong color values. Therefore the fast Leica lenses also have rather large front elements.
Q: That is especially noticeable with the Summitar. But doesn't the general speed of the lens become higher due to the larger front element?
MAX BEREK: No, only the evenness of illumination is improved. The important thing is the pupil diameter of the diaphragm in its apparent size as seen from the front of the lens through the front elements. With modern, fast lenses this is usually smaller than the free diameter of the front element for the following reasons: take a lens in your hand, hold it in front of a piece of white paper and look straight down into the lens. You will see a white circle of light. That is the opening that is influencing the center of the image area. Now tilt the lens a little bit. You will notice immediately that the speed of the lens has to become less toward the margins of the picture. To avoid this vignetting as much as possible, it is necessary to make the front element larger than the relative opening at the center of the lens would necessitate.
Q: Herr Professor, I heard that Leitz has already designed lenses with an opening of f/0.85. Why are these lenses not generally available?
MAX BEREK: That was a special edition for X-ray photography. For general photography such speeds of course aren't of value. The depth of field alone is so narrow with such openings that three dimensional objects could not be shot. And even with X-ray photography it became apparent that the lens should be stopped down to at least f/1.2 to obtain a greater resolution.
Q: I recently read about a “rubber lens” (ed. Note: from the German Gummilinse, a common expression for zoom lens) which enables you to dial in various focal length at will. Why don't you make something like this instead of manufacturing eight different lenses in focal lengths from 28mm to 400mm, which I can't afford altogether and for which I would have to lug around a whole suitcase?
MAX BEREK: You would need a suitcase made especially for your zoom lens and I think every Leica amateur would object to lugging around such a monster.
The lens would really be very large, unhandy and heavy since it would have to consist of more than 20 elements and we shouldn't even talk about the cost; it would be higher than the combined cost of all the Leitz specialty lenses it had replaced. For large, professional cine cameras such a lens might have its place, but the Leica will do better to stay with its interchangeable lenses. Besides, you will never need all the Leica lenses at the same time. Rather, you will usually get by with three, a normal, a wide angle and a long lens like the 90mm Elmar. Even an amateur can afford such an outfit if he buys it little by little.
And the term “rubber lens” is not exactly appropriate; it is rather a lens with continuously adjustable focal length.
Q: To what degree are there fault free lenses?
MAX BEREK: Scientifically, there is only one faultless optical system as Göttingen mathematician Felix Klein demonstrated, a combination of plane mirrors. Such a system creates unrecordable images.
We do not have the ability to create images totally without faults. In this sense there are no perfect lenses. The problem is to correct the mistakes so that, in view of the practical application of the lens, it can be considered perfect.
Q: What certainly does the buyer have of obtaining a perfect lens? Is one as good as the next?
MAX BEREK: Everything depends on tolerances; they must be so close that the remaining errors will have no influence. That is assured by a production system thought out to the smallest detail, one that covers the entire creation of a lens. It starts right at the cutting of raw pieces of glass by controlling impurities, stress lines, etc. This control increases during the manufacture of each single element, while shaping it by grinding, while polishing and mounting it and combining it with the rest of the optical system. When the lens to be finally passes all tests prescribed during the individual working steps, it still won't be delivered, but will be tried for critical test exposures. Thus the buyer in each case will have the assurance of getting a perfect lens.
Max Berek's house in Wertzlar
But I want to mention something else which now and then has led to questions. All Leica lenses are manufactured of high quality glass types which have to be specially melted. With some of these glasses, for which very characteristic optical properties are prescribed, it is impossible to totally eliminate little air bubbles within the glass. In the first days of the Anastigmats such bubbles were even seen as a mark of a good lens. To some degree this is also true today. These bubbles do not have any influence on correction and can be accepted without reservation.
Q: Can you tell us what innovations we amateurs might expect in reference to Leica lenses?
MAX BEREK: Substantial innovation cannot be expected in the near future. It is little known though that besides the 50/1.5 Summarit we also offer an 85/1.5, the Summarex. The long focal length makes it especially suited for portraits, photojournalism, stage and vaudeville photography and similar purposes. You might also be interested to know that the line of Telyt lenses with focal lengths of 200mm and 400mm has been widened with an additional lens in the extreme focal length of 800mm. Of course, this lens is only of interest to the professional.
Now I would like to say something to finalize. With the state of the art of our optics, a well done picture is not so much an optical problem as it is a problem of the technical precision of the camera, the properties of the taking material and especially the training of the user. The feeling for a good picture can best be developed by enlarging or projecting one's pictures large scale. Only then will the amateur have the full enjoyment of his work.
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Please Note: The photographs in this article are from the Book “Max Berek , Schöpfer der ersten Leica Objektive, Pionier der Mikroskopie” (Max Berek, creator of the first Leica lenses, pioneer of microscopy), used with permission.
Lindemanns Verlag
Nadlerstrasse 4
70173 Stuttgart
ISBN 978-3-89506-284-1
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The handwritten note is quite interesting, but hard to read. I see that Berek made specific notes regarding the individual lens elements. Do you have any idea what the numbers are referring to?
ReplyDeleteThe list below the lens diagram is referring to the individual lens elements. The first numbers indicate the surface radius of the front and rear of each element in millimeters. The infinity mark simply means that that particular surface is flat without any curvature at all. The next number indicates the maximum or minimum thickness of the lens elements as well as the width of the spaces in between. The third and fifths numbers are very similar. They indicate the refractive index of the glass used at two different wave lengths of the light. Finally, the fourth numbers are the Abbe numbers of the glass, indicating the dispersion of the types of glass used.
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