Preface to the First Edition

This book can be regarded as an extension and modernization of Conrady’s 50-year-old treatise, Applied Optics and Optical Design, Part I of which was published in 1929.* This was the first practical text to be written in English for serious students of lens design, and it received a worldwide welcome.

It is obvious, of course, that in these days of rapid progress any scientific book written before 1929 is likely to be out of date in 1977. In the early years of this century all lens calculations were performed slowly and laboriously by means of logarithms, the tracing of one ray through one surface taking at least five minutes. Conrady, therefore, spent much time and thought on the development of ways by which a maximum of information could be extracted from the tracing of a very few rays.

Today, when this can be performed in a matter of seconds or less on a small com- puter—or even on a programmable pocket calculator—the need for Conrady’s somewhat complicated formulas has passed, but they remain valid and can be used profitably by any designer who takes the trouble to become familiar with them. In the same way, the third-order or Seidel aberrations have lost much of their importance in lens design. Even so, in some instances such as the predesign of a triplet photographic objective, third-order calculations still save an enormous amount of time.

Since Conrady’s day, a great deal of new information has appeared, and new procedures have been developed, so that a successor to Conrady’s book is seriously overdue. Many young optical engineers today are designing lenses with the aid of an optimization program on a large computer, but they have little appreciation of the how and why of lens behavior, particularly as these computer programs tend to ignore many of the classical lens types that have been found satisfactory for almost a century. Anyone who has had the experience of designing lenses by hand is able to make much better use of an optimization program than someone who has just entered the field, even though that newcomer may have an excellent academic background and be an expert in computer operation.

For this reason an up-to-date text dealing with the classical processes of lens design will always be of value. The best that a computer can do is to optimize

*A. E. Conrady, Applied Optics and Optical Design, Part I, Oxford University Press, London (1929); also Dover (1957); Part II, Dover, New York (1960).

the system given to it, so the more understanding and competent the designer, the better the starting system he will be able to give the computer. A perceptive preliminary study of a system will often indicate how many solutions exist in theory and which one is likely to yield the best final form.

A large part of this book is devoted to a study of possible design procedures for various types of lens or mirror systems, with fully worked examples of each. The reader is urged to follow the logic of these examples and be sure that he understands what is happening, noticing particularly how each available degree of freedom is used to control one aberration. Not every type of lens has been considered, of course, but the design techniques illustrated here can be readily applied to the design of other, more complex systems. It is assumed that the reader has access to a small computer to help with the ray tracing; otherwise, he may find the computations so time-consuming that he is liable to lose track of what he is trying to accomplish.

Conrady’s notation and sign conventions have been retained, except that the signs of the aberrations have been reversed in accordance with current practice. Frequent references to Conrady’s book have been given in footnotes as “Conrady, p. . . .”; and as the derivations of many important formulas have been given by Conrady and others, it has been considered unnecessary to repeat them here. In the last chapter a few notes have been added (with the help of Donald Feder) on the structure of an optimization program. This information is for those who may be curious to know what must go into such a program and how the data are handled.

This book is the fruit of years of study of Conrady’s unique teaching at the Imperial College in London, of 30 years of experience as Director of Optical Design at the Eastman Kodak Company, and of almost 45 years of teaching lens design in The Institute of Optics at the University of Rochester—all of it a most rewarding and never-ending education for me, and hopefully also for my students.

Rudolf Kingslake

A Special Tribute to Rudolf Kingslake

Rudolf Kingslake’s very first paper, written when a student at Imperial College London, was coauthored by L. C. Martin, a faculty member. The paper, “The Measurement of Chromatic Aberration on the Hilger Lens Testing Interferometer,” was received 14 February 1924 and read and discussed 13 March 1924. Immediately following it was a paper by Miss H. G. Conrady, listed as a research scholar since she had already graduated in 1923. Miss Conrady’s paper was entitled “Study and Significance of the Foucault Knife-Edge Test When Applied to Refracting Systems” (received 21 February 1924; read and discussed 13 March 1924).

The formal degree program in optics at Imperial College was founded in the summer of 1917 and entered its first class in 1920. Hilda Conrady was a member of that class. Her father was A. E. Conrady, who had been appointed a Professor of Optical Design. Professor Conrady’s work and publications were definitive in the literature and in the teaching of optical design. In 1991, Hilda wrote a fine article in Optics and Photonics News describing “The First Institute of Optics in the World.”

Hilda and Rudolf became lifetime partners when they married on September 14, 1929, soon before they left England because Rudolf had been appointed as the first member in the newly formed Institute of Applied Optics at the University of Rochester in New York. It is interesting to note that for the academic year 1936–1937, L. C. Martin, on the faculty of the Technical Optics Department at Imperial College London, and Rudolf Kingslake exchanged faculty positions. With Rudolf’s usual sense of humor, he commented that “Martin and I exchanged jobs, houses and cars . . . but not wives.”

With the publication of this new edition of Lens Design Fundamentals, which originally appeared in 1978, Kingslake’s published works cover a period of 86 years! His last major new publication was The Photographic Manufacturing Companies of Rochester, NewYork, published by The International Museum of Photography at the George Eastman House in 1997; so even using this data point his publications covered 73 years! We should also note that his extensive teaching record extended well into his 80s and touched thousands of students. His “Summer School” courses were indeed legendary.

The Early Years

Rudolf Kingslake’s interest in optics started in his school days; he wrote about his “entrance into optics” and said, “father had a camera handbook issued by Beck that contained many diagrams of lens sections, which got me wondering why camera lenses had four or six even eight elements?” This interest continued and he noted, “so when I found out that lens design was taught at Imperial College in South Kensington, I was determined to go there. The college fees were not too expensive and father soon agreed to my plan.” Thus Rudolf entered the program in 1921, graduated in 1924, continued on into graduate school with a two-year fellowship, and earned his M.Sc. degree in 1926. And so, a very distinguished career was launched.

His graduate work at Imperial College was very productive, and a number of significant papers were published including works such as “A New Type of Nephelometer,” “The Interferometer Patterns due to Primary Aberrations,” “Recent Developments of the Hartmann Test to the Measurement of Oblique Aberrations,” “The Analysis of an Interferogram,” “Increased Resolving Power in the Presence of Spherical Aberration,” and “An Experimental Study of the Best Minimum Wavelength for Visual Achromatism.”

After graduation Rudolf was appointed to a position at Sir Howard Grubb Parsons and Co. in Newcastle-upon-Tyne as an optical designer. His notes say, “designed Hartmann Plate, measuring microscopic and readers for Edinburgh 30-inch Reflector. Took many photographs, translated German papers, Canberra 18-inch Coelostat device, Mica tests, etc.” In June 1928, he published a paper in Nature entitled “18-inch Coelostat for Canberra Observatory.”

Apparently Parsons didn’t have enough work for him to do, so he accepted an appointment with International Standard Electric Company in Hendon, North London. In Hendon he “worked on speech quality over telephone lines and made lab measurements of impedance using Owen’s bridge at various frequencies from 50 to 800 (cps). This experience was good for me as it gave me a glance at the business of electronics, designing telephones. I was paid weekly, so gave them a week’s notice when I went to America.”

The Institute of Applied Optics

Once in the Institute, Kingslake quickly developed the necessary courses and laboratory work in the Eastman Building on the Prince Street Campus. Dr. A. Maurice Taylor, also from England, joined the Institute with responsibility for physical optics. The permanent home was the fourth floor of the newly constructed Bausch and Lomb Hall on the River Campus. Despite a heavy teaching and planning load, Rudolf managed to produce a number of significant publications for major journals. These included “A New Bench for Testing

Photographic Lenses,” which became the standard in the United States. A joint paper with A. B. Simmons, who was an M.S. graduate student in optics, reported on “A Method of Projecting Star Images Having Coma and Astigmatism.” Then followed “The Development of the Photographic Objective” and “The Measurement of the Aberrations of a Microscope Objective.”

The final paper during that period (1929–1937) was a joint paper with Hilda Kingslake writing under her maiden name of H. G. Conrady entitled “A Refractometer for the Near Infrared”; she was working as an independent researcher. Rudolf reports that “in this joint paper the design of the refractometer was mine. Miss Conrady assisted with the assembly, adjustment and calibration and made many of the measurements on glass prisms.”

The Kodak Years

Even though Rudolf moved in 1937 to Eastman Kodak at the request of Dr. Mees, Kodak’s Director of Research, a very important arrangement was made for Kingslake to continue to teach on a half-time basis—a position that he held long after his retirement. His last Summer School in Optical Design was held in his 90th year.

Although the work at Kodak was often proprietary (and even classified during the war years), he was able to publish a continual stream of important papers in a wide range of professional refereed journals associated with major scientific and engineering societies. At the time of his move to Kodak, Rudolf commented that his “industrial experience had been lamentably brief—that more than anything else, he needed experience in industry for greater competence in teaching an applied subject.” He was correct of course. In 1939, the Institute of Applied Optics had a slight name change to The Institute of Optics.

Once Kingslake joined Kodak, he quickly made significant contributions to the design and evaluation of photographic lenses for both still photography and motion picture equipment. Topics included wide-aperture photographic objectives, resolution testing on 16-mm projection lenses, lenses for aerial photography, new optical glasses, zoom lenses, and much more (see the Appendix for specifics).

Some of the summary articles give an excellent perspective of the state of the art and its impact. His paper “The Contributions of Optics to Modern Technology and a Buoyant Economy” is a good example of the results of his exposure to the industrial world. In a joint paper, “Optical Design at Kodak,” with two members of his team, he summarized his work at Kodak. Finally in 1982 he produced “My Fifty Years of Lens Design.” What a good summary!

Books

Kingslake had an impact on the discipline of optical science and engineering through his writings in a number of texts and contributions he made to various handbooks. His first single-author volume, Lenses in Photography, was published in 1951; the 1963 second edition turned out to be a classic.

In 1929, Professor Conrady had published Part I of his book, Applied Optics and Optical Design, but he was not able to complete Part II before his death in 1944. He did, however, leave “a well advanced manuscript in his remarkably clear handwriting.” Rudolf and Hilda worked together to compile and edit the manuscript for publication in 1960. Hilda added a biography of her father that appears as an appendix in Part II. Part I and Part II were released together by Dover. The Journal of Applied Optics published a revised version of the Conrady biography (see App1. Opt., 5(1):176–178, 1966). Next came two chapters in the SPSE Handbook of Photographic Science and Engineering on “Classes of Lenses” and “Projection.” “Camera Optics” appeared in the Fifteenth Edition of the Leica Manual.

His major work, however, was Lens Design Fundamentals published by Academic Press in 1978. This new edition is authored by R. Kingslake and R. Barry Johnson and is significantly revised and expanded to encompass many of the significant advances in optical design that have occurred in the past three decades. Academic Press published two more Kingslake books: Optical System Design (1983) and A History of the Photographic Lens (1989). In 1992, SPIE Optical Engineering Press published Optics in Photography, which was a much revised version of Lenses in Photography.

Kingslake’s final single-author volume, mentioned earlier, The Photographic Manufacturing Companies of Rochester, New York, was published by The International Museum of Photography at the George Eastman House. Rudolf was a dedicated volunteer expert curator of the camera collection together with auxiliary equipment. As a result of his work, he wrote many articles in the Museum’s house journal Image. These articles started in 1953 and continued into the 1980s; Rudolf called them notes!

Working with his publisher, Academic Press, Rudolf launched and edited the series Applied Optics and Optical Engineering. The first three volumes were published in 1965 and Kingslake contributed chapters to all of them. The next two volumes appeared in 1967 and 1969; they were devoted to “Optical Instruments” as a two-volume set (Part I and Part II). This writer was asked to join Rudolf as a coeditor of Volume VI (and to contribute a chapter, of course). The series continued under the editorship of Robert Shannon and James Wyant with Rudolf Kingslake as Consulting Editor.

Acknowledgments

In the later years of Rudolf Kingslake’s life, he asked me if I would take charge of his affairs. After consultation with his son and with the family lawyer, I agreed to take power of attorney and subsequently be executor of his will, since his son predeceased him. At his request, I agreed to take all his professional and personal papers to create an archive in the Department of Rare Books and Special Collections of the Rush Rhees Library at the University of Rochester.

Martin Scott, a long-time colleague and friend of Rudolf’s at Kodak and at the International Museum of Photography, joined me and did the major part of the work of putting the archive together. In addition, Nancy Martin, the John M. and Barbara Keil University Archivist, was invaluable, knowledgeable, and dedicated to our task. The catalogue of this archive is now available online.

This tribute to him is a selected and revised version of a Plenary address, “Life and Works of Rudolf Kingslake,” presented at the conference on optical design and engineering held in St. Etienne, France, 30 September to 3 October 2003; it was published in 2004 in the proceedings (Proc. SPIE, 5249:1–21).

Brian J. Thompson

Provost Emeritus

University of Rochester

Rochester, New York