Evolution of zoom lens optical design technology and manufacture

Zoom lens optical designs have advanced for over a century with technology and manufacturing development transforming the capability of zoom lenses. Although there have been many different kinds of zoom lens developed, most fall into three main categories: fundamental, enabling, and improvement technology. Indeed, some technology and manufacturing developments had been crucial to zoom lens optical design development in a pioneering way and yet are now generally considered obvious or even simple. In comparison, other developments are incremental improvements that may be combined together like building blocks. Altogether, the capability of zoom lenses has greatly improved to the extent that today many major performance characteristics are now equal to or come close to matching those of fixed focal length lenses. Some of these characteristics including size, weight, cost, producibility, and general image performance are dependent on widely differing technologies. For example, optical design, coatings, refractive materials, surface types, and the use of computers with suitable optical design software are just some of the technologies that, when combined, have driven the continuous development of zoom lenses and their optical designs. Using zoom lens optical design examples taken from literature and patents, the evolution of zoom lens optical design technology and manufacture is described following a mainly historical order.