LUDWIG J. BERTELE: A PIONEER OF GEOMETRIC OPTICs

A couple of months ago I received an email from member Oscar Fricke asking whether I might like to review this book, which he had helped his father, our Founder and President Emeritus Rolf Fricke, to  translate. It  turns out  that  I had previously noted the book on  line  and  it  had  piqued my interest – but unfortunately too many books do so to be practical. Yet given the offer and the added fact that Rolf had managed once again to translate an important book of photo- history, an affirmative answer was easily made.

The German original had been published in 2016, written by the son of the famous lens designer. The English-language edition was published earlier this year in 150  hard  copies, plus an eBook. As I am writing this, many of the hard copies have been snapped  up,  but  that  should  not  deter  those  of us interested in optics or the history of lenses for miniature cameras from locating a copy one way or another, for this is a fascinating and well written story about Bertele the man as well as a look into optical development from the 1920’s to 1950’s. While it is not mentioned specifically, it also dovetails somewhat with the story of the Leica camera and its own lens development, a history likely to be more familiar to us at LHSA. Bertele’s contribution to the development of camera lenses was enormous – think the Ermanox  camera with  its fast Ernostar lens in the early 1920’s to the various Zeiss Sonnars and Biogons. And there is much more, in areas of photogrammetric lenses, and wide-angle flat-field oculars for microscopes and other instruments.

The book  alternates  between  Bertele’s   personal   history and the history of his lens designs, with early chapters also covering the history of lenses back into prehistory, and the development of optics since the beginning of the photographic record. Bertele (1900-1985) was an autodidact from a poor family who never went formally beyond secondary school,  and was self-taught in mathematics and the Seidel Imaging Errors and formulas and their corrections. He went well beyond these concepts in his innovative designs –  more  or  less as a pathfinder of new formulas and ways of concep- tualizing what was needed for specific optical purposes. Unfortunately, the book does not  address  the  actual process of his daring deviation from accepted thinking in much detail, but there are in the book reproduced patents and technical information, as well as many images taken with his lenses. It should be said, moreover, that Bertele often did not get along, nor fit in that well with his bosses, likely due to his innovative thinking more than his personality. As such, he worked for a series of companies through his career before settling down finally at Wild Heerbrugg for his last years. The list of companies he worked for includes Ernemann, Zeiss Ikon, Steinheil, and finally Wild. It helped that early in his career there was a move towards the inventor, rather than just  his  company,  being listed on new patents, and indeed Bertele at least once moved to a new job with his own latest lens patent application in  hand.

Much of the latter half of Bertele’s story concerns his very specialized lenses for mapping,  military,  and  scientific purposes. These are described in some detail, along with appropriate images when applicable. For example, there is the account of how the extraordinarily detailed stereoscopic imaging of the giant Buddha statues in the Bamiyan Valley of Afghanistan that had been performed in 1974 using Bertele’s photogrammetric lenses recently allowed a contour  map  of the statues (with contour lines every 20cm) to be generated. Even though the statues had been destroyed by the Taliban, with these maps their rebuilding might be possible. We are shown a contour map of one of the statues as an illustration. And in a heading on lens computations, we are shown both actual log tables and hand written sheets for ray tracing, as well as a picture of a MADAS calculating machine which was the successor to the logarithms and precursor to an early digital computer in such tasks. Further, in an epilogue near the end of the book, the author covers new developments in optics that have accrued since his father’s time, such as aspheric grinding technology, gradient optics with a continuously varying index of refraction, and rapid focusing or lens zooming via electro-active polymers within a lens element.

Bertele was a secular humanist who mostly eschewed political action except when it was important to show his convictions. He left the Catholic Church over both antisemitic remarks he heard from the pulpit and also the Pope supporting Italy in    the Ethiopian Campaign of 1935-36. During the Third Reich, he rehired, over considerable protest from management, a valued worker who had been imprisoned for political activities. He helped disabled persons find employment in his department, as well supporting organizations devoted to the protection and well-being of animals. “When he was asked about his worldview, he once commented that he considered himself to be a leaf on the ‘tree of humanity.’ A leaf, which by means of his activity made a small contribution to the development of the tree, of the culture, but which at some point would fall off, in order to make room for a new generation.  His scientific worldview had no room for the God he came to know from his Catholic upbringing.” (pp. 59-60)

The book is chock full of photographs: almost every area of interest covered in the text has its corresponding images, and these are  well chosen and  well reproduced. The translation is skillfully done and flows naturally, not the easiest thing to accomplish as this reviewer knows from personal experience working with other writers’ texts. Extensive picture credits and references are listed as befits such a scholarly work.

The Hardcover Book is 10 x 8.5″, 122 pages

ISBN-10: 3728139556, ISBN-13: 978-3728139559.

Published by: vdf Hochschulverlag AG an der ETH Zürich. The hardcover book as available is about 75.00.

The eBook in English can be purchased through links from vdf at: https://vdf.ch/ludwig-j-bertele-english-e-book.html. CHF 48.00, Euro 46.00.