Optics comes with its own etymology, traceable name words that usually signify something of the development of a lens, a camera, even, sometimes, a company itself. In the 1890’s the eponymous C.P. Goerz Optical Company (founded in Berlin in the previous decade) developed a lens that was, in actuality, two back-to-back lenses, with the idea being that the aberrations in one lens would correct the aberrations in the other. The theory proved to work, and the resulting lens was originally called the Double Anastigmat Goerz. In 1904 this clunky name was shortened and became the acronymic “Dagor,” a name many people are familiar with as the lens was popular, successful, and manufactured into the 1970’s. Originally designed by Emil von Höegh, the Dagor is a six element lens, consisting of two cemented triplets.
Around the same time Dr. Paul Rudolph of another German company, Carl Zeiss, was busy developing a lens which ultimately became one of the most popular and widely duplicated lenses in history. His creation was the evolutionary result of years of lens design, culminating in a four-element design called a Tessar. The meaning of that name would be obvious to anyone who had studied Greek in school; nowadays, those people are rarer. But the word is from the Greek tessares, meaning, simply, “four.” This name is illustrative of the fact that its design contains four separate pieces of glass (in three groups, with a positive crown glass element in the front, a negative flint glass element in the center, and a cemented pair in the rear). Every major photographic lens manufacturer has produced its own version of this lens, especially as the patents have expired.