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The Schott Heard Around the World

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OK, confessions first. My assignment for this piece was to write a Holiday Photography Article. And to do it quickly because my last article was overdue. And to make it something cheery and concise since my last article was a long technical piece on how to test a lens. I tried to come up with an idea, but I really wasn’t in the mood because I was pretty worn out from writing that overly long technical piece. So, I thought I’d write another article on the early history of lenses because I enjoy those. “But no”, they said, “we need a holiday article”.

Then something else dawned on me. I wrote two Holiday Photography Articles last year, one on Photographing Holiday Light and another on Taking Indoor Holiday Photos. Since I did two last year we could just consider one of them a really early submission for this year’s Holiday Article. And I could write about what I wanted to, right? But, NOOOoooo, I’m supposed to write something festive. “Go write a holiday photography article”, they told me. “Something pertinent to the Christmas season”.

Okay, lets try this. Between 1880 and 1905 there were roughly 25 Christmas seasons, so writing about that era should cover the Holiday festivities part just fine. And I’ll try to make this festive. But festive or not, it was a pretty cool time. After 15 years of basically no improvement in photographic lenses, the 25 years I’m going to write about today were an explosion of technical improvements. And most of the explosion came from 4 guys working in the same city.

The city is Jena, Germany and I’m pretty sure they have spectacular Christmas festivities there, so it’s the perfect setting for a holiday article. Yep, that’s my story and I’m sticking with it. Anyway, I Googled it and found this picture of Jena at Christmas time to set the mood. (Plus, Kristin never reads the articles, so she’ll open this, see the picture, and figure I followed instructions.)

And I was lucky since Google says “The Christmas Market of Jena is the oldest Christmas fair in Thuringia”. So there you go. I’m pretty sure Thuringia is old, since its in Europe and all, so if they have the oldest Christmas fair in Thuringia, it is the perfect setting for a holiday article. So, let’s go back to a Christmas circa 1880 and see what was going on with photographic lenses.

From our Last Episode

So, what I’m going to write here is the history of photographic lens development, Part II. If you haven’t read the first one, From Petzval’s Sum to Abbe’s number don’t worry about it, I’ll summarize it here. Between the development of the first camera and the mid 1860s, lens designers made several major discoveries:

1) Wollaston (1830s) demonstrated that bending a convex or concave lens into a meniscus shape could help flatten the field, allowing more than just the center of the photograph to be in focus.

Figure 1: A convex lens bent to a meniscus shape

2) Chevalier’s Landscape lens (1840s) demonstrated that a doublet made of crown and flint glasses of different types of glass could correct longitudinal chromatic aberration, making a lens achromatic.


Figure 2: An achromatic doublet.

3) Petzval’s Portrait Lens (circa 1850) showed that an air space between elements let the designer correct for other aberrations better than two cemented elements could.


Figure 3: Design of Petzval’s Portrait Lens. Note the small air space between the rear elements.

4) Dallmeyer and Steinhill (1860s) found that a lens made of symmetrical reversed elements placed around a central light baffle was virtually distortion free.


Figure 4: Design of Rapid Rectilinear Lens (courtesy Wikepedia Commons)

If you look carefully, you’ll see these basic lens types are included in many of today’s modern designs.


Figure 5: A modern zoom lens. You can see meniscus elements, an achromatic doublet, fixed air spaces between elements, and reversed symmetrical elements.

We also found that there was big money to be made in lenses, and that overly intelligent academic types (like Petzval) got robbed blind by astute businessmen with low scruples (like Voigtlander). In today’s episode, which I almost entitled Revenge of the Nerds (but that didn’t sound very festive), we’ll see another intelligent academic team up with an astute businessman to triumph over the Evil Herr Voigtlander (well, Voigtlander’s kids, actually, but still). And unlike the early days of lens development, this period is one where polite gentleman behaved like, well, gentleman. So, it is a holiday story after all, good triumphs over evil, everyone is nice and polite, and photographers get better lenses.

The Quiet Years

By the late 1860s, photographers had Petzval’s Portrait lens for (Duh!) portraits, and the Rapid Rectilinear lens for architectural photography and landscapes. There were a lot of minor modifications of these lenses made for mostly marketing purposes (I would make a snide comment here about some Nikon version II lenses, but its the holidays so I’ll be nice). There were two other designs of some importance that occurred during this time. One was very popular for a while but became a dead end. The other was not at all popular at the time, but became hugely important later.

The Symmetrical Wide Angle Lenses

Photographers had a portrait lens and a landscape lens, but they didn’t really have a lens, back in the 1860s, that would let them shoot a wide-angle scenic image. Thomas Sutton, an English photographer, noticed the wide angle of view he saw when looking through one of those water filled snowglobes (This is true. I’m not just stretching to make this a holiday article, but its a nice touch, don’t you think?) and designed a lens that consisted of a water filled globe.

The obvious name for this lens would, of course, be the Globe Lens or Water Lens, or something similar. But Sutton decided that The Sutton Panoramic Lens would be much catchier and it was marketed under that name. While some were made by Ross and Co., it required a curved camera plate and special camera, so it never was very popular.


Figure 6: The Sutton Globe lens, Copyright Earlyphotography.com/uk

As an aside (and you know I love my asides) Sutton became famous not because of his lens, but because he worked with James Clerk Maxwell to make the first color photograph in 1861. Sort of. He took three separate images of a piece of Tartan ribbon, each with a different color filter. The three negatives were then projected through three projectors (yes, they had projectors, called magic lanterns back then) each with the same color filter on them. If you got the projectors all lined up and focused just right, you could see the color image reproduced below.


Figure 6: The first color photograph, taken in 1861. It has nothing to do with the article, really, but its kind of cool. And the colors are kind of Christmassy, and I’m supposed to be writing a holiday article. Image courtesy Wikepedia Commons.

Not too surprising, this form of color photography didn’t catch on. Magic Lanterns remained very popular though, their popularity driven, like so many things photographic, by their ability to project artistic images of nude ladies in the gentleman’s clubs of the day.

About the same time a couple of Americans, Harrison and Schnitzer, took the globe idea but thought they would eliminate the water (and most of the globe for that matter). They kept the spherical surface shape of the elements, but made them achromatic doublets. It wasn’t a complete globe anymore, just two pieces of a globe. But Sutton hadn’t used the globe name, so they called it The Globe Lens. Later, after Schnitzer passed away, Harrison couldn’t help himself and started calling it the Harrison Globe lens.

The Globe Lens could take a 40 degree field-of-view image, which was quite wide for the day, but its best aperture was only f/30. A very similar (and probably better) lens, the Pantoskop, was designed and marketed by Emil Busch in Germany. These lenses were THE wide angle lenses of the 1860s and 1870s, but mostly because they were the only ones available. They drifted into obscurity by the turn of the century when the good stuff came along.


Figure 7: The Harrison Globe lens (schematic above, actual sample below. Note that the outside elements would fit the theoretic curve of a sphere or globe. The rear element (the lens is resting on its hood) protrudes significantly.

The Double Gauss Lens

The thing I like best about the Double Gauss lens, is that Gauss had nothing to do with it. Gauss was a famous mathematician in the early 1800s who described a novel telescope lens made up of two meniscus shaped lenses, one positive and one negative, partly separated by an air space. Mathematically, he knew that such a lens would be insensitive to the various wavelengths of light and so would have no chromatic aberration. That was true, but otherwise It was a pretty poor lens and was very difficult to make.

In 1888, an American, Alvin Clark decided if one Gauss type lens was bad and expensive, putting two together around a central stop (like the Rapid Rectinear and Globe designs) would probably be a brilliant idea (he was American, after all, so doing things the hard way didn’t faze him). He introduced the Double Gauss Lens which was marketed by Bausch and Lomb for a a few years before being quietly dropped. Like most other lens designs of the day, the available optical glass just wasn’t up to the task and the lens really offered nothing positive other than the cool Double Gauss name.


Figure 8: An Original Double Gauss lens design.

Later, however, the Double Gauss design would come to dominate the photographic lens market and they still are used frequently in lenses today. But we can’t get there until we talk about glass a bit.

Crowns and Flints

Other than the Globe type lenses, no significant improvements in lens design occurred between the mid 1860s and the 1880s. The reason progress came to a stop was because of the limited types of glass available. From an optical standpoint, the most important characteristics of glass are its Refractive Index (how much it bends light passing through it) and its Dispersive Index (how much it separates the various colors of light). Lensmakers of the day had two types of glass to work with: Crown Glass and Flint Glass.

Crown glass, which was the type of glass used to make windows, was produced mostly of silica with a strong pinch of potassium oxide. It received its name because glass blowers blew it into a crown or hollow globe before flattening it to make window glass. Crown glass bent light a little bit (low refraction) and separated the colors a little bit (low dispersion).

Flint glass was so named because the source of silica for it was originally flint chips. The flint contained a significant amount of lead which made the glass heavier and more refractive (meaning it bent light more) and more dispersive (it separated colors more). These qualities of flint glass lent itself to making sparkling cut-glass drinking glasses (what we now call leaded crystal glass) and fake gemstones (rhinestones are made from flint glass).

Not only were lensmakers limited to two types of glass, there was a lot of proprietary ‘secret formula’ stuff going on in the glassmaking industry, so one manufacturer’s flint glass might be quite a bit different from another’s. And not being able to measure just how much the qualities of a batch of glass differed in refraction and dispersion made things a little more variable than we would find acceptable today.

The Professor and the Lensmaker II

The first great lens advances were started by the ideas of Professor Petzval which were (arguably) stolen by Herr Voigtlander. Another professor, Ernst Abbe at the University of Jena, apparently didn’t hear how poorly things had worked out for Petzval and took a side job with a local optical instrument maker who wanted to make his microscope designs more scientific. Abbe had recently invented the Refractometer, a device that could measure just how much a given type of glass bent the light passing through it, so he was just the boy to start getting this glass chaos in order.

Using his refractometer, he began determining the amount of refraction and dispersion of different types of glass and quantitated it by what we call Abbe’s number. Abbe, like Petzval, was a mathematician and knew if he slapped numbers around for a while he could fix things without all the trial-and-error design that was common in the day. Within a short time he had developed formulas for microscope illumination and for producing sharp images in complex optical systems. Abbe’s employer recognized Abbe was a smart boy and unlike Voigtlander, he didn’t try to steal his ideas. Instead, he made him a partner and chief microscope designer for the firm.

Unfortunately, none of the glass available at the time met the criteria Abbe knew was necessary for advanced lens design. Even worse, he had to import his optical glass from England and France since there wasn’t a good source of such glass in Germany. And you know the Germans weren’t too keen on depending on the English and French to supply them with things they didn’t have. So Abbe started talking glass with a University of Jena chemistry student named Otto Schott, who also happened to be the son of a glassmaker.

Schott showed Abbe some different types of glass he was developing in his chemistry lab, Abbe went to his partner for funding, and in 1882 they opened the Schott Glassworks in Jena. Within 6 years Schott Glassworks had a catalogue of 44 different types of optical glass, many of which were not available elsewhere. By 1893 they had developed Barium crown and Borosilicate flint glasses, which had higher refraction and lower dispersion than other glass types — the first low dispersion elements were now available for photographic lenses and lens design could leap forward.

As an aside, Abbe’s employer died in 1888 leaving Abbe the sole owner of the company, Carl Zeiss AG. Zeiss AG was also the principal owner of Schott Glassworks which became the world’s leading supplier of optical and laboratory glassware, heat resistant glass used in incandescent lamps, and glass cookware (what we now call Pyrex). So, this time around the Professor did quite well for himself.

He also did quite well for others, too. Professor Abbe was a social reformer and under his leadership Zeiss and Schott became the first manufacturers to set an 8 hour workday for employees (the norm then was 12 to 14) as well as the first to give sick pay and paid vacations. Abbe eventually donated all of his shares of the company to form a research institute and to provide employee stock options, things that were unheard of at the time. As a result, Zeiss AG and Schott Glassworks attracted some of the most talented employees in Germany.

As a further aside, after World War II Jena was located in a section of Germany originally controlled by the U. S. but soon to be given over to the Soviet Union. The U.S. felt the glassworks so important that in late 1945 the Air Force relocated most of the top designers and scientists to West Germany before turning control of Jena over to the Soviets. Led by Erich Schott, the company restarted in Mainz as Carl Zeiss Oberkochen and returned to preeminence as an optical company (they eventually supplied optical glass to the U. S. space program) and lensmaker.

The Jena factory was dismantled and transported to the Soviet Union where it became the Kiev Camera Works, maker of infamous cheap copies of prewar Zeiss Contax cameras and lenses. The East German government, along with many of the remaining employees, restored the Schott and Zeiss plants in Jena and began selling lenses labelled Carl Zeiss Jena. So for a while you could buy your Zeiss design lenses and cameras from Russia (Kiev brand), East Germany (Zeiss Jenna brand), or West Germany (Zeiss AG brand). It was a complicated time.

Back to the Subject

The new glass, particularly the Barium and Borosilicate glass, had the potential to achieve the Holy Grail of lens designers: lenses free of the spherical aberration, coma, and astigmatism — the so-called anastigmatic lens.

Anastigmat probably should be considered a Southern word, since it’s a double-negative: Stigma means point, and the prefix “A” means without or no, so Astigmatism means without point or no point. In a lens with astigmatism a point on the object doesn’t show as a point in the image, it is blurred.

“An” also means no. (I’m not sure why the Greeks needed two different prefixes for “No” but I have some Greek relatives and they’re all very negative people. So I guess its like how Eskimos have 17 words for snow, the Greeks just needed a lot of words for no.).

But anyway, An-a-stigmat would mean “no non points”. Or something like that.

Then Came Rudolph

Remember, it’s supposed to be a holiday article.

Oddly enough, the first use of the new Schott glass types was by Voigtlander, the biggest photographic lensmaker of the day. But they just used the new glass in an old design so the improvements were minimal. Abbe designed some new microscope objectives for Zeiss AG using the new glass types, but he wasn’t a photographic lens designer.

However, while Abbe was running Zeiss AG, Schott glassworks, and enacting all kinds of social reform he did one other really bright thing. He hired a Jena mathematician and physicist, Dr. Paul Rudolph, as his chief lens designer. Rudolph immediately grasped the possibilities offered by the new glass and in 1892 he developed Zeiss’ first photographic lens. He called it the Anastigmat since it was, not surprisingly, an anastigmatic lens. Or at least pretty close to one.

However, since Anastigmat was already a word Zeiss couldn’t make the copyright for that name stick and later renamed the lens The Protar. The Protar used a standard front element like the Rapid Rectilnear lens but the rear element was made of the new Barium and Borosilicate glasses.


Figure 9: The Zeiss Anastigmatic (Protar) lens, low dispersion elements in blue.

The Anastigmat / Protar was a good wide-angle lens but Dr. Rudolph found it still had limitations. He realized the Double Gauss design could be modified using the newer types of glass he had at his disposal, and in 1896 released a new design, the Planar, which is basically a double-gauss design in which the central elements are cemented pairs. By making the central element a pair instead of a single lens, the cemented “buried surface” in these elements gave an additional refraction change. This allowed further correction of aberrations when designing the lens. As an end result the Planar was far superior to the Protar.


Figure 10: Original Zeiss Planar Design.

Think about it: the Planar lens was designed in 1896. There have been modifications, off course, since that time in coatings and glass types. Extra elements have been added to the front and rear of the double-gauss Planar group, and the elements may be made unsymmetrical. But the lens is still with us today and considered one of the better prime lenses made. Over 300 variations have been made over the years, including the Leica Summicron, Schneider Xenotar, Rodenstock Heligon, and many of the higher quality, wide aperture prime lenses made by Nikon, Canon, and others through the 1970s.


Figure 11: A Zeiss Protar from the turn of the century. Note the early internal leaf shutter adjusted by the ring around the lens.


Figure 11: The Planar influence (highlighted in green) is apparent even in superb modern lenses like the classic Nikon 55mm f1.2 (left) and the Nikon 24mm f1.4 (right).

In 1902 Rudolph did some more tinkering with the original Anastigmat / Protar lens, separating the front cemented doublet by an airspace and changing the order of the positive and negative elements. He found this lens had much better resolution than the Protar and it was released as the Zeiss Tessar. Fairly inexpensive to produce, the Tessar was sold by the millions. It was also produced, either under license or with small modifications to work around patent restrictions, by dozens of other manufacturers. Tessar type lenses include the Leitz Elmar, Kodak Ektar, Pentax Takumar, and Voiglander Skopar.

Yes, by this time Zeiss had long since passed Voigtlander as the preeminent lens maker and Voigtlander was now copying the ideas of others. Wait, Voigtlander copying ideas was how this all started. So, as it turns out, the academic professors won this round of the lens design wars.


Figure 11: Zeiss Tessar Design.

The Most Important Lens of All

The boys from Jena certainly dominated lensmaking at the turn of the century.

Zeiss, Abbe, Schott, and Rudolph developed the new glass and created new designs that revolutionized photography, allowing wide fields of view and wide apertures without distortion for the first time. They achieved the Holy Grail of lens design, the truly anastigmatic lens. And the Planar and Tessar designs provided the foundation for a significant number of lenses that remained in use throughout most of the 20th century. Other lenses were designed, excellent lenses, by other companies. But the Schott Glassworks division of Zeiss supplied the glass that made most of them.

Speaking of excellent lenses, there was one lens designed at this time that I left out. Neither the Planar nor the Tessar, although both were superb, were THE lens designed at the turn of the century. That was another lens, designed by an Englishman named Dennis Taylor and produced by two other (and unrelated) Englishman named Taylor. They named it the Cooke Triplet. It was the Triplet that became the basis for more subsequent lens designs than the Planar, the Tessar, or any other lens. But that’s a long story, perhaps best saved for the next holiday article I’m required to write.

Why was it named the Cooke Triplet, though, you might want to know before I end this? Because Dennis Taylor, while designing it, worked for the Cooke of York Optical Designers. Cooke of York did not wish to produce the lens, but allowed him to take it to Taylor, who produced it. Dennis Taylor, out of respect for his employer, insisted the lens should have their name. Photography had indeed progressed from the idea-stealing and finger-pointing of the 1860s, to a profession of polite gentleman by the turn of the century.

References

  • http://www.fundinguniverse.com/company-histories/Schott-Corporation-Company-History.html
  • http://encyclopedia.jrank.org/articles/pages/1015/Evolution-of-the-Photographic-Lens-in-the-19th-Century.html
  • http://image.eastmanhouse.org/files/GEH_1961_10_05.pdf
  • Kingslake, Rudolph: A History of the Photographic Lens. Academic Press, London, 1989.
  • http://www.mhs.ox.ac.uk/sphaera/index.htm?issue8/articl7
  • http://en.wikipedia.org/wiki/Ernst_Abbe

3 Responses to “The Schott Heard Around the World”

Mark Dallmeyer said:

Hello: my ancestral uncle, J.H. Dallmeyer, was instrumental with the manufacturing of the Ross lens. Dallmeyer was known to have produced the main telephoto lens for Ross and Zeiss in the UK. Additionally Dallmeyer was funded by Warren DeLaRue and became well known in cameras and telescopes as well as telephotography. The interesting link may be the use of Fraunhofer glass to produce these lenses. Joseph Fraunhofer is the discoverer of the Fraunhofer lines in the 1800′s and today Fraunhofer is a company throughout Germany with a vast technology base. The tie in to me personally is that in 1985, I worked for Crosfield electronics, a division of DeLaRue. In 2009, I began my representation of Fraunhofer FIT and IVI for the US market. In 2010, I was responsible for Dallmeier electronics, a surveillance company based in Regensburg. Neither company knew the other existed. These are certainly interesting times in the lives of lenses.

Adam said:

Without doubt, one of the most enjoyable reads I’ve ever had, and I’m not limiting that to things I’ve read on the internet. Truly fantastic, thank you!

My only qualm is that I don’t know if I should praise you on behalf of others for refraining from some horrible Schott glass drinking pun, or complain about you depriving the vocal minority (me and maybe one other guy) of reveling in its awfulness.

I would never trade it for the Schott heard round the world pun, but it IS a holiday article. Why not have a double Schott?

Christopher Vradis said:

[“An” also means no. (I’m not sure why the Greeks needed two different prefixes for “No” but I have some Greek relatives and they’re all very negative people. So I guess its like how Eskimos have 17 words for snow, the Greeks just needed a lot of words for no.).
But anyway, An-a-stigmat would mean “no non points”. Or something like that. ]

Well, not exactly right, but not exactly wrong, either. Astigmatism is a pathology of the eye and yes, means something like “without or no points”, as you say, (I’m not a doctor!). So Astigmatic is the word used to describe one who suffers from astigmatism. An-astigmatic, on the other hand is the exact opposite, it describes one who does not suffer from this pathology. The prefixes “an” and “a” (sometimes also “ap”) are actually one and the same prefix, “a”. Which one is used in each word, mainly depends on the first letter of the word (and from other grammatical phenomena).

So, anastigmatic is more correct and sounds better than “aastigmatic” and, furthermore, it is more simple than saying “the one who does not suffer from astigmatism”.

Don’t worry about your Greek relatives. They’re negative probably because you’re Italian !

Great article ! Like all you wrote on lenses history !

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