Albert Koenig, lens designer for Carl Zeiss. ========================== Some of Albert Koenig's work included: Telescope objectives. Koenig and the group he led at Zeiss designed the apochromatic 'B' objective, which in the 1930s was probably the finest small telescope objective manufactured. Available in 60mm to 200mm aperture. Eyepieces. Koenig designed many types of eyepieces. The term 'Koenig eyepiece' is widely used today but is not a precise description for a particular design. His earlier 'Koenig eyepiece' designs included an eyepiece with a singlet eye lens & a doublet field lens. Most modern Koenig eyepieces are '1,2,1': a singlet eye lens, a doublet in the middle, and a singlet field lens; but 1,1,2, and 1,2,3 eyepieces (and other configurations) are also commonly called 'Koenigs'. All have a wide field of view, up to 70 degrees, with the simpler examples showing 'fuzzy edges' in short focus telescopes. Prisms. The Abbe-Koenig prism is variously credited to one or both of these designers, though Koenig in 'Telescopes & Rangefinders' names it an Abbe prism. It was described in 1895 by Czapski (without mentioning Koenig), and patented by Zeiss in 1902. It has been widely used in binoculars and telescopes, from the 1905 Hensoldt Dialyt (German patent 180,644; 14 April 1905), to Zeiss models of the 1920s (7 x 50 Noctar, 10 x 50 Dekar, and military D.F. models including a12 x 50), to the present day (Zeiss Victory series, among others). Lens Coating. Schomerus' history of Zeiss included the development of antireflection lens coatings at Zeiss by Alexander Smakula in the 1930s, adding that 'Dr. Albert Koenig initiated these concepts'. (Schomerus, Friedrich. Geschichte des Jenaer Zeisswerkes 1846-1946. Stuttgart: Piscator, 1952.) Books. Koenig, Albert. Das Fernrohr. pp82-211, Grundlagen der Astrophysik, erster Teil, Berlin: Springer, 1933. Koenig, Albert. Die Fernorohre und Entfernungsmesser. Berlin: Julius Springer, 1923. (1st ed. 207pp) Koenig, Albert. Geometrische Optik. Leipzig: Akademische Verlagsgesellschaft, 1929. (570pp) Rohr, Moritz von. Die Bilderzeugung in optischen Instrumenten vom Standpunkte der geometrischen Optik. (Die Theorie der optischen Instrumente. vol. l) (contributors include A. Koenig) U.S. Patents: 708,720 Koenig prismatic telescope Sept. 9, 1902 754,076 Koenig low power telescope March 8, 1904 880,028 Koenig telescope Feb. 25,1908 2 objectives, 1 eyepiece 908,279 Koenig double telescope Dec. 29, 1908 not roof prism 918,752 Koenig double telescope April 20, 1909 battery commanders' scope, large roof prism in front of eyepiece 920,756 Koenig binocular telescope May 4, 1909 not roof prism 947,971 Koenig binocular telescope Feb. 1, 1910 hand held, IPD adjustment 1,034,804 Koenig lookout telescope Aug. 6,1912 no prism Fontana mast 1,085,868 Koenig objective system; 'dedicated barlow' Feb. 3, 1914 1,094,724 Koenig variable power telescope April 28, 1914 no prism 1,097,646 Koenig lookout telescope May 26, 1914 1,170,912 Koenig lookout telescope Feb. 8, 1916 2,015,527 Koenig eyepiece with prism Sept. 24, 1935 2,206,195 Koenig eyepiece July 2, 1940 2,217,281 Koenig wide angle eyepiece ==================================================== The Life of Albert Koenig. By Horst Koehler. Appendix to: Albert Koenig & and Horst Koehler. Die Fernorohre und Entfernungsmesser. Berlin: Julius Springer, 3rd ed., 1959. Translated by Chris Plicht, May, 2003. Albert Koenig was born on 16 August 1871 as the son of a 'Baumeister' (master builder) in Plettenberg (Westphalia). After finishing high school (humanities, classical), he studied mathematics and physics at Jena and Berlin. In 1895 he received his Ph.D. as a pupil of Winkelmann. The title of his thesis was 'Beitraege zur Theorie der Fresnelschen Beugungsspektra' (Contribution to the Fresnel Diffraction Spectra); based on a suggestion by E. Abbe who also supervised this work. Even before finishing his thesis, on 01 October 1894, Koenig joined the Zeiss-Works in Jena. In 1895, after his successful promotion, he assumed the task of calculating astronomical objectives. Remarkably, in his first years, Zeiss created the three element astronomical achromatic objective, which was widely distributed as the B-Objektiv. From 1900 onwards Koenig became more involved in calculating optical systems for terrestial telescopes. Until the end of his life he was head of the department for terrestial telescopes at the Zeiss-Works at Jena. He worked on developing terrestial telescopes (binoculars, sighting scopes, observation telescopes, range finders etc.); and began, in 1921, the calculation of the optics for geodetic and precision measuring instruments. In the same year he also began managing the scientific section of the department for geodetic instruments, a post he held until 1930 in addition to his other tasks. Koenig died on 30 April 1946, aged almost 75, after a brief illness. Even there in bed he calculated optical systems until only a few days before his passing. In 52 years of professional activity Koenig developed a large number of optical systems, which are impossible to list individually. About 70 patents in his name were issued. His most important creations include: - Telescopic eyepiece with apparent field-of-view up to 90 degrees. - Telescopic eyepiece with large eye relief, and a long focal length while maintaining field of view up to 70 degrees. - Astigmatism-corrected telescope objective of 3 unseparated lenses (Hemiplanar for fields up to 25 degrees). - Standard telescope objectives plus single- and multi-element erecting systems with aperture ratios up to 1:1.5. - Geodetic telescopes with negative focussing lens, with precalculated position of the anallactic point. - Reading microscopes for scales on geodetic instruments, with wedge micrometers. - Measuring microscopes for precision measuring instruments, with working distance up to 100 mm, telecentric optical path on the object-side, and distortion completely removed. - Projection objectives with telecentric optical path on the object-side, for workshop projectors, plus illumination optics for workshop projectors. - A large number of binoculars, observing telescopes, aiming telescopes, range finders, alignment testers, projection devices, and many other products. This enormous labor was done with a minimum of assistants. Koenig rarely employed more than three optical calculators, which he selected by applying very strict criteria. He was an authority on the art of calculating optical systems with a minimum of work. He drew on rich experience, a treasure of self taught rules, formulae, approximations, and 'Rules of Thumb', plus a natural intuition for optics. Although he limited calculations to the absolute minimum, he was rarely disappointed by the finished product. His methods were remarkable; he would calculate individual examples of a type of optical system, as many as possible, in advance, independently of current production needs. Thus he was in a position, when a need for any type of optics arose, to quickly produce a solution from his ongoing investigations, and to supply the workshop with data which needed only minor alteration. His brilliant memory and his well-defined optical instinct helped him, so that he often amazed his colleagues when quickly producing solutions for complicated optical systems. Also extensive was the scientific and publishing activity of Koenig. He was participating in an authoritative way on widening the knowledge of the theory of optical imaging in the last half century. This is well documented in numerous articles contributed to collected editions and handbooks, namely the following: 1. Die Theorie der optischen Instrumente (The Theory of Optical Instruments), M. von Rohr, editor; Berlin 1904. Chapters by Koenig: a. Durchrechnungsformeln (Calculation Formulae) (together with M. von Rohr) b. Die Theorie der sphärischen Aberration (The Theory of Spherical Aberration) (also together with M. von Rohr) c. Die Theorie der chromatischen Aberration (The Theory of Chromatic Aberration) 2. Grundzuege der Theorie der optischen Instrumente nach Abbe, S. Czapski and O. Eppenstein, editors, Leipzig 1924. Chapters by Koenig: a. Farbabweichung und ihre Hebung (Color differences and their removal; achromatization) b. Verfahren zur Messung der Bestimmungsstuecke optischer Instrumente (Procedures to measure optical Instruments; physical and optical characteristics: radii, thickness, refractive index, aberrations, etc.) 3. Lehrbuch der Physik (Textbook on Physics), by Mueller-Pouillet, Braunschweig 1926. Chapter by Koenig: Optische Instrumente (Optical Instruments) 4. Handbuch der Astrophysik (Manual on Astrophysics); G. Eberhardt, A. Kohlschuetter, & H. Ludendorff, editors; Berlin 1933. Chapter by Koenig: Das Fernrohr (The Telescope). 5. Handbuch der Experimentalphysik (Manual on Experimental Physics), W. Wien and F. Harms, editors, Leipzig 1929. Volume 20.1, Physiologische Optik (Physiological Optic) (together with C. Pulfrich, after whose death he took over the work). Volume 20.2, Geometrische Optik (Geometric Optic). Publications by Albert Koenig include: 1. Die Fadenentfernungsmesser bei den Fernrohren mit Zwischenlinse der Zeiss- Wild’schen Nivellierinstrumente (The Wire Range Finder, in Telescopes with Intermediate Lens Element, of the Zeiss-Wild Levelling Instrument), Zentralzeitung fuer Optik und Mechanik 42, 197 (1921). (In this publication, Koenig was the first to describe a useful calculation to find the anallactic point of telescopes using a negative focusing lens element.) 2. Der neue Zeiss-Theodolith. (The new Zeiss Theodolite) Zentralzeitung fuer Optik und Mechanik 45, 151 (1924). Also remarkable was Koenig’s scientific activity during his first professional years. Most of these papers, written with careful editing, appeared from 1895 to 1903 in the 'Zeitschrift fuer ophtalmologische Optik' and the 'Zentralzeitung fuer Optik und Mechanik'. There are about 100 reports, of which one is especially important, refuting and disproving H.D. Taylor’s attack on the contemporary German methods of calculating optical systems (Zentralzeitung fuer Optik und Mechanik 45, 122 (1924). In his personal life Koenig was modest and he disliked grand honors. His honorary degree 'Dr.-Ing.' from the Technische Hochschule in Stuttgart, and the Gold Medal awarded to him at the 1938 Worlds Fair in Paris for his achievements regarding terrestial telescopes, were not recognized or noticed. With unequalled loyalty he served the needs of technical optics with an inner motivation. Not even personal distress slowed down his creativity. I am obliged with deep gratitude to him, who introduced me to practical geometric optics in the difficult times after the collapse in 1945, who prepared me to succeed him in his post, and who was a fatherly friend and counselor during the relatively short time of our collaboration. ========================================= May 2003 home page: http://home.europa.com/~telscope/binotele.htm