This article will outline a brief history of early lens design, starting with the simplest 2 element topologies for daguerreotype cameras. This can be considered as background my article on symmetrical designs. This is by no means complete. For that you will need to read many chapters in the books I list in my references.
Tracing lens development
The history of photographic lens development is naturally mixed with that of other optical devices: telescopes, microscopes, projectors, and cinema lenses. All use similar optical principles but have different constraints, based on the intended use. My contemporary interest is in cameras that shoot 135mm film or their digital equivalents. But inventions in the early years primarily targeted cinema cameras and other devices, so these will also be described when appropriate.
My interest began by reading old forum threads about lens patents. it soon became clear that a narrative constructed in this way could be misleading, since many ideas were not developed into actual products. And these products, even if they were first to market, were not necessarily financially successful or influential on future work. It’s difficult to know the tenor of the times from documentation. Which lens designers were the talk of the town? Which new discoveries were whispered about in cafés? Which inventions were, in fact, important? Some of this can be gathered from how popular the given solution became, how much it was copied by subsequent inventors, and how many products based on this solution actually sold.
In discussing lens formulae it is common to use the notation “x elements in y groups”, which specifies the total count and configuration of individual pieces of glass. A “group” here is two or more elements cemented together. But this notation describes the optics quite poorly. Four elements in two groups could mean two pairs of doublets, with an air gap between. But it could just as readily be applied to one lens element plus three cemented together into a triplet. The common specification is minimal to the point of obscurity, omitting the shape of the glass, the material and its refractive index, the relative position of the aperture, etc. Vendors might additionally provide a diagrammatic representation of the optical structure. From this we can at least ascertain the overall topology, which is enough to trace lens lineage.
In passing I will note the confusing term “lens”. This rightly refers to an individual optical element in an optical design. But it also means the total assemblage of lens elements and other physical structures that you mount on a camera. The context should make the meaning clear.
Before continuing, it is worth reading the glossary of common terminology.
Here are the common lens elements that are combined to create an optical design.
The challenge of lens design is to render a perfect virtual image onto the focal plane. Shaped glass can be used to bend light rays as they travel through that material, the refractive index being a numerical measure of how much the light bends (typical values range from 1.5 to 1.8). Lens elements are either positive, which act to converge light, or negative, which diverge light.
A strong positive element with a weaker negative element is a standard combination. The overall effect is still converging, but such compound lenses can reduce chromatic aberration, spherical aberration, and coma. However further elements are required to reduce field curvature and astigmatism.
Early lens designs
The cameras of Louis Daguerre (1787–1851) required innovations in the then nascent understanding of optics. Charles Chevalier (1804-59) applied his knowledge from telescopes and microscopes to the new science of photography.
By 1839 his simple combination of biconcave and biconvex elements became the standard for daguerreotype cameras sold by Alphonse Giroux. At the same time N.M.P. Lerebours (1807-1873) produced a 2 element design using plano-concave and biconvex elements for Gaudin, with the stop place much closer to the glass. Since these cameras were limited to f/15 many otherwise important aberrations could be ignored. Such French landscape lenses (as they were called) were popular for a century.
In bright sun, such a lens required 30 minute for an exposure. Encouraged by a prize being offered for any improvement, Joseph Max Petzval (1807-1891) set about designing optics fast enough to be used for portraiture.
His solution was a 4 element in 3 groups design using a cemented doublet telescope objective with a separate achromat. The resulting 150mm f/3.6 was about 20 times as fast as the landscape lens. This made up for its defects, including severe vignetting. (This look has become associated with portraits of the time.)
Manufactured by P.W.F. Voigtlander (1812-1878) in Vienna, the design was popular until the 1920s. Even after such designs were superseded for camera optics, Petzval lenses remained in use for projector s. Today, photographers are rediscovering and adapting antique lenses of this form to discover the special optical character of designs quite different from modern photographic lenses.
Between 1860 and 1890 Thomas Rudolph Dallmeyer (1859-1906) made many innovations, including a portrait lens that was sold as the Bausch & Lomb f/4 Series A.
In 1878 Johann Friedrich Voigtlander (1779-1859) created a different 4 element configuration that was common on 8mm and 16mm projectors.
Another lasting design became known as the Cooke triplet. This was created by Harold Dennis Taylor (1862–1943) at T. Cooke & Sons, York, UK in 1893. In fact he registered three similar patents with the air gaps and stops changed in size and disposition.
Such lenses were manufactured by Taylor, Taylor, and Hobson (Leicester), beginning a relationship between Cooke and TTH that would last until the present day.
The Cox appendix on Cooke triplets (pages 496-511) lists about 150 lenses available for 135 format, in 68 different optical design. But of these only four are used by several manufacturers. The apparent profusion hides a standardisation of lens designs.
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