TECHNES Encyclopedia Database

As Kingslake provocatively declared in his 1934 article “The Development of the Photographic Objective,” lens history “divides itself naturally into two parts, the ‘old’ period from 1812 to 1886, and then the “anastigmat” period from 1886 to the present day.”^[1] 1886 does not mark the release of a particular lens. Rather, 1886 marked the year that the Zeiss Glastechnisches Laboratorium Schott und Genossen (Schott and Associates Glass Technology Laboratory) began distributing barium crown glass. This glass, and the new kinds of glass produced by the glass works, led to a significant expansion of applications that rapidly moved beyond microscopy and photography. The Glass Works helped make glass more than a raw material: it made glass a technology.

Optical Glass: Material as Technology

While Abbe succeeded in emphasizing the professional benefits of a scientifically oriented process of lens production to microscopists, another element of design became increasingly insurmountable to the working quality of scientifically designed lenses: the raw glass. In 1876, on the occasion of the exhibition The Special Loan Collection of Scientific Instruments in South Kensington, London, Abbe wrote an impassioned report on the state of the optical field. Abbe lamented the fact that the optician had at his disposal “a fully-developed theory and thoroughly-tested practice – everything, in fact, except suitable glasses for the construction of the necessary lenses.”^[2] Physicists were limited by the physical properties of the glass available for lens construction.

Furthermore, the market for scientific instruments in the mid-nineteenth century was quite restricted. The demand for glass industries was predominantly for window glass and glassware. Consequently, glass manufacturers had “little or no economic incentive to improve the quality of glass used in optical instruments.”^[3] Abbe suggested that improvements in the glass-making industry would benefit not only microscopy, but “all sciences and arts that need optical appliances.”^[4] He sought to link lenses to a broader ideal of using science to improve society, but found no promise or incentive for this change in the commercial industry alone. However, through significant governmental state support, Abbe was able to establish the foundation of the Glass Works with Otto Schott.

Otto Schott and the Glass Works

Abbe’s 1876 report attracted the attention of Otto Schott, a young chemist who had completed a doctorate on “Contributions to the Theory and Practice of Glassmaking” in sheet glass and was pursuing melting experiments in his father’s sheet glass factory.^[5] In response to Abbe’s report, Schott wrote Abbe a letter inquiring whether some experimental lithium glass that Schott had made might have optical applications. Schott sent samples of his experimental glass to Abbe, and the two struck up a collaboration.^[6] In 1882, Schott settled in Jena, and shifted from small-scale experimental glass meltings that he had been performing in Witten to large scale experiments.

Zeiss’ 1884 establishment of the Glastechnisches Laboratorium Schott und Genossen, otherwise known as the Glass Works, marked a profound shift in the production of precision lenses at Zeiss. In the same way that Abbe’s processes affirmed professional beliefs in the scientific construction of instruments, Schott’s work established optical glass as a technical material: one that was “precisely specified and reproducible in its properties.”^[7]

The modernization of glass was a practice of subjecting glass to increased measurement, elevating it from a material to a technology. Glass with technically specified properties – that could also be reliably reproduced! – was a key material not only for optics, but for “virtually all technology, i.e., in the end, for modern life in general.”^[8] The modernization of glass was also a practice of making it possible to think of vision and technology as interchangeable. As so many early trick films demonstrated, believing in a lens’ invisible mediation of vision and nature was often a revelatory experience.

Barium Crown Glass

One of the most significant glass formulas that emerged from the Glass Works was for barium crown glass. Barium crown glass enabled the construction of new types of photographic lenses as barium crown glass enabled a wider functional aperture than existing combinations of crown and flint glass allowed.^[9] The main contention at the time was that “high aperture and a wide angular field [of view] were incompatible.”^[10] As a result, many existing lens designs chose between allowing chromatic aberration (a function of too strongly curved glass) or spherical aberration (a function of too weakly curved glass). Barium crown glass quickly became an optical standard for photographic lens construction because of its “absolutely clear transmission power” and freedom from chromatic and spherical aberrations.”^[11] Barium crown glass, in combination with flint glass, enabled the simultaneous correction of both chromatic aberration and spherical aberration without significant compromise to the amount of light that came in through the lens.

Barium crown glass was a necessary part of the design for Zeiss’ “Anastigmat” lens. (As noted previously, “anastigmatic” is primarily used to describe a class of lenses that reduce both spherical and chromatic distortion. But, in this particular instance, “Anastigmat” does refer to the particular physical design of Zeiss’ 1890 lens.) The physical properties afforded by barium crown glass enabled lens designers to overcome what was largely assumed to be a stable and immutable relationship between light and refraction.

Professional practice to date had suggested that the larger the relative aperture on prior lenses, the greater the necessary aberrations. This established belief – that there was a fundamental limit to the imaging capabilities that could take place at brief moments of time – had significant implications for the ability of photographers and scientists to capture images on the flexible recording mediums that emerged in the 1890s. While “film” is often held to be a fundamental material of cinema, without a lens that could capture a distortionless image while still allowing enough light for registration on the recording surface, cinema might have looked different in its early years.

Barium crown glass enabled lens designers to create distortionless lenses, like the Zeiss Anastigmat, that many designers had previously thought to be physically impossible. In creating new kinds of optical glass, Zeiss chemist Otto Schott was hailed by the Deutsche Glastechnische Gesellschaft (the German Glass Society) as “the creator of modern scientific glass technology.”^[12] In transforming glass from a “raw” material into a “technical” material, Schott enabled glass to be systemically designed and reliably used to produce precision optical systems. Schott “allowed optics to become a technology.”^[13]

One of the reasons that the Glass Works was so dramatically successful was that, in succeeding in finding the means to reliably and repeatedly create new kinds of glass, the Glass Works met both domestic and international demands for scientifically designed optical glass. In the early nineteenth century, high quality optical glass predominantly came from the English firm The Chance Brothers, Taylor, Taylor and Hobson, and the French company Parra-Mantois.^[14] German opticians were dependent on imported optical glass for their instruments – as late as 1888, Germany imported nearly all of its optical glass from Britain.^[15] Both domestically and internationally, the Glass Works found a rich demand for the many growing forms of industrial and scientific applications of glass – and, according to a 1904 publication, the volume of optical glass production fell far behind the greater output of glass for lamps, thermometers, and other applications that required glass capable of resisting sudden and significant variations in temperature.^[16]