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Optical Design & Engineering

Rudolf and Hilda Kingslake

From oemagazine July 2002
30 July 2002, SPIE Newsroom. DOI: 10.1117/2.5200207.0005

In 1929, Rudolf Kingslake and his new bride, Hilda Conrady Kingslake, uprooted their lives in England to take their chances in America. At age 26, Kingslake was hired as one of the first two faculty members at the University of Rochester's fledgling Institute of Optics (Rochester, NY). That alone would be a mark of distinction in anyone's lifetime, but for Rudolf Kingslake, it was only the first step in a career that spanned 60 years as an educator and lens designer. In 2002, Rudolf and Hilda Kingslake have both begun the journey into their 100th year. This article is a tribute to their longevity and to their stamp on the world of lens design and optical engineering.

From curiosity to career

Rudolf Kingslake was born in 1903 in England. His father was an amateur photographer and young Rudolf became curious about how the lenses on his cameras worked. He had read Photographic Lenses, A Simple Treatise by Conrad Beck and Herbert Andrews that showed sections of lenses; Rudolf wondered why some lenses required six elements and some only four. He soon learned that Imperial College (London, UK) had a department of optics where lens design was taught, so decided to follow up on what was becoming more than just idle curiosity to him. The program had only begun in 1917; he enrolled in the class of 1921 with the program in its infancy. He was one of four students in the second full-time graduating class.

Eastman Kodak Design Group, circa 1965.

A. E. Conrady, professor of optical design, was among the instructors. In what proved to be serendipitous for Rudolf, Professor Conrady's daughter, Hilda, was also enrolled as a student of optics; she graduated with two other students in the first graduating class. Since the school was small in the early years, the classes worked together. As Rudolf wryly explained, "We all worked together and got to know each other pretty well."1

Rudolf received his MSc in 1926 from Imperial College and was a Beit Fellow during that time. Upon graduation, he did optical design work and performed telephone research engineering, both for companies in England. Then came the invitation from Rush Rhees, president of the University of Rochester (U of R) in the 1920s. SPIE Fellow and 1975 -1976 President Brian Thompson, who is also professor emeritus at U of R and former provost, commented that Rhees "recognized the proven strength and future potential of Rudolf. He reported to the Trustees: 'I have been fortunate in finding a man ideally trained for geometrical and optical design . . . he has published eight paper . . . and by training and experience, he is admirably fitted to contribute largely to the development and significance of our new enterprise.' That new enterprise was, of course, The Institute of Optics." 2

Rudolf and Hilda were married in England in 1929 before their move to the Institute of Optics; this year they mark their 73rd anniversary.

As Thompson pointed out, Rhees was astute in 1929. Although he did not hire Hilda, "I am sure that he knew that he was getting a package deal since Hilda had already three years of industrial experience and had published several papers."2

Recording history

Rudolf and Hilda in San Diego, August 1976.

Thompson noted that "Hilda is perhaps best known for her knowledge and writing in the organizational history of our field, particularly the 50-year history of the Optical Society of America and the 50-year history of The Institute of Optics."2

Hilda and Rudolf published together extensively; those publications include topics such as "A New Refractometer for the Near Infrared," published in the Journal of the Optical Society of America in 1937; "Alexander Eugene Conrady," published in Applied Optics in 1966; and "The Contributions of Optics to Modern Technology and a Buoyant Economy," published in Optica Acta in 1968.2

In the classroom

Rudolf was an assistant professor of geometrical optics and lens design at the Institute of Optics until 1935 when he became an associate professor. From 1936 to 1937 he served as an exchange professor at Imperial College. He then began what was to be a 25-year career with Kodak as a lens designer. Within two years he became head of the lens design department and in 1956 was appointed director of optical design and optical engineering. During his career at Kodak, he also continued his association with the U of R as a part-time associate professor. He received his DSc from Imperial College in 1950.

Rudolf's specialization was in the aberration of lenses and their measurements and the effects of aberrations on optical images. Through 50 years of teaching, he taught many students, including Robert E. Fischer (Optics 1; Westlake Village, CA).

In an interview he conducted with Kingslake in 19841, Fischer asked if he thought people working in optical design who were coming out of the current classes had enough understanding of how things were produced. Kingslake replied, "The only way to really understand something is to do it yourself." In the days long before computer lens design software, this was painfully obvious to Fischer, who learned the intricacies of log tables and ray tracing from Kingslake (see "Ray tracing and log tables" sidebar).

Publications and honors

Kingslake authored several landmark books including Lenses in Photography (Garden City Books, 1951), Lens Design Fundamentals (Academic Press, 1978), Optical System Design (Academic Press, 1983), and A History of the Photographic Lens (Academic Press, 1989). He is also the author of Optics in Photography (SPIE Press, 1992). He published A History of the Photographic Objective, which SPIE Fellow Warren Smith, a former Kingslake student, describes as a "must-read" (see "Mentor, colleague, friend" sidebar). Kingslake is also the author of at least 70 scientific papers.

Kingslake (left) and General George Goddard.

Kingslake received the 1964 Progress Medal from the Society of Motion Picture and Television Engineers, the Ives Medal from the OSA, and the Gold Medal from SPIE in 1980. He served as vice-president and president of the OSA in the mid- to late-'40s and was elected Fellow in 1959. He is a member of the Physical Society of London and a member of the Society of Photographic Scientists and Engineers of which he was elected Fellow in 1962.

In honor of Kingslake, SPIE established The Rudolf Kingslake Medal and Prize in 1974. The award and prize are awarded annually in recognition of the most noteworthy original paper to appear in SPIE's journal, Optical Engineering, on the theoretical or experimental aspects of optical engineering.

A dry wit

Bill Price (left) and Kingslake. Price was a long-time colleague of Kingslake's at Eastman Kodak.

While students admired Kingslake's grasp of and display of knowledge of all aspects of lens design, they also were the lucky recipients of his droll sense of humor. When Robert Fiete won the 1999 Rudolf Kingslake Medal and Prize for his paper "Image Quality and λFN/p for Remote Sensing Systems" he realized he lived close to Kingslake, so decided to visit him with the medal in tow.3 Fiete grinned with the memory. "He said that he had never actually seen the medal before and then quipped that the image on it looked a lot more like his father than like him." Fiete went on to add, "Dr. Kingslake shared many stories and past experiences with us. He said that he has always maintained that SPIE is the best organization for people who want to have fun with optics."

SPIE Fellow Robert Shannon (Univ. of Arizona; Tucson, AZ) particularly appreciated Kingslake's ability to add wit at unexpected times (see "Enduring and respected" sidebar).

At the special banquet and retrospective sponsored by SPIE during its Annual Meeting in San Diego, which honored Rudolf and Hilda in 1983 in celebration of their 80th birthdays, Brian Thompson revealed Rudolf's comment when asked about turning 80. "There is nothing very special about being 80 -- after all, anyone can have an 80th birthday; all they have to do is live long enough."

Kingslake holding a psaltery made by his son, David.

This philosophy has proven true for nearly 20 more years; Rudolf and Hilda Kingslake, both nearing 100 years old, have lived humble lives that have managed to touch an enormous number of people around the world. While they are both known for their expertise in classical lens design, to those who have had the honor to know them, they are most often remembered for their warmth and hospitality, for their modesty and their kindnesses.

At a banquet honoring the Kingslakes on the kick-off of the Rudolf and Hilda Kingslake Seminar Series in Optical Engineering at the U of R in 1985, Thompson acknowledged the many honors that have been bestowed upon the Kingslakes, but articulated what many believe: "That list of honors, no matter how large it grows, represents but a small thank you for all they mean to us as friends, intellectual colleagues, and teachers."


1. Optical Engineering Reports, January 1984.

2. Remarks from Brian Thompson at a banquet and retrospective honoring Rudolf and Hilda Kingslake, 1983, San Diego, CA.

3. oemagazine, February 2001, Vol. 1, no. 2, p. 39.

Thanks to Brian Thompson, (Univ. of Rochester) and Martin Scott (Director of scientific imaging, Eastman Kodak) for their assistance with information and the many photos for this article.

Ray tracing and log tables

by Robert E. Fischer

I had the great opportunity to be a student in Dr. Rudolf Kingslake's lens design course while an undergraduate at the University of Rochester in the mid-1960s. What struck me the most was his total and complete command of every aspect of the technology. Rudolf Kingslake's derivations of the many mathematically intensive principles were flawless, fluent, and downright uncanny.

In those days, mainframe computers were coming into usage and electronic calculators were also just appearing. I remember the recommendation on the first day of the course to buy a book of log tables . . . I didn't, nor did anyone else in the class.

During most of Dr. Kingslake's career, ray tracing and the optimization of a lens was done largely by hand. Prior to computers and electronic calculators work was done on mechanical calculators (the ones that went "chunkety-chunkety-chunk"), and the designer had to work with log tables. Ray tracing was a slow and arduous task at best. The designer had to develop a significant high-level understanding of the task at hand. Today, many people feel that simply pushing the buttons on the computer will optimize a lens. While there is occasionally some truth in this, the understanding of the technology as taught by Dr. Rudolf Kingslake clearly gave us all that high level of understanding of the task at hand.

The many students that studied under the fine guidance of Dr. Rudolf Kingslake have a lot for which to be thankful.

Robert E. Fischer is the founder and president of Optics 1, Westlake Village, CA. He was president of SPIE in 1984 and is the current SPIE Treasurer.

Mentor, colleague, friend

by Warren Smith

I first encountered Rudolf Kingslake as a student in his then notorious course in lens design at the Institute of Optics at the University of Rochester. His course was regarded as strenuous by the students, but it was probably the best investment of time that any of us made in our academic careers. The lectures were meaty, and somewhat dry, but Rudolf had a droll sense of humor. His idea of ribaldry was a story dealing with a chamber pot that the students at an English university regularly up-ended on the spire of one of the college buildings, and which was just as regularly removed by a marksman from the college staff, until one enterprising student somehow managed to carry out the annual prank with a pot full of cement, which hardened before the college marksman could plink it to pieces.

He was indeed a splendid teacher, but in my later years I've found his brilliance as an author to be something that continues to amaze me. His book Optical System Design covers an unbelievably broad collection of topics and does it in a way so easy to understand that, as an author myself, I find reading it is pure pleasure. Another of his many excellent books, A History of the Photographic Objective, was obviously a labor of love for the author; it is a terrific book, and a "must read" for any lens designer.

On top of all this, Rudolf is always a consummate gentleman, charming, modest, and kind to a fault. It has been a truly great pleasure and honor to have known him as a mentor, colleague, and friend for so many decades.

Enduring and respected

by Robert R. Shannon

Rudolf Kingslake is one of the most enduring and respected individuals in the field of optical design.

His many years of teaching the core design course at the Institute of Optics served to provide the knowledge base for at least two generations of lens designers. The comprehensive course notes from his evening course at the University of Rochester in the 1950s served as an important resource during a period when there were few current textbooks that covered the subject. His clear exposition of the principles of aberration computation and links to the influence of lens element shape on aberration contribution were important to the understating of lens design as an art. Although Rudolf has, on occasion, stated that he just did not understand how lenses really worked, his teaching and writings belie this modest front.

Rudolf's book on lens design was a landmark summary of the state of the art of the subject at mid-century. His founding of the multi-volume book series on Applied Optics and Optical Engineering contains valuable and heavily referred-to material on a wide range of optical engineering topics that kept pace with the growth of the field. His book on the development of the photographic objective is a classic in technological history.

I have good memories of him at professional meetings over the years. He is always thoughtful and precise and has the ability to lace his comments with often unexpected humor that helps make the subject more interesting and memorable. Those who were fortunate enough to be a part of the Institute of Optics in the '50s have fond memories of the active part that he and Hilda played in the social and professional life of the organization.