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| The Making of Zeiss Ikon |
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| An idea becomes a camera |
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Chapter 4: What We Wanted to Improve
With the new Zeiss Ikon, we at Carl Zeiss wanted to create a high-quality camera system leaving nothing to the imagination. We set very high standards along the way. Our product developers, engineers, physicists and technicians are all passionate camera enthusiasts. With the Zeiss Ikon camera we had the unprecedented opportunity of influencing the creation of a camera for our lenses. We did not let this chance slip away: we incorporated our decades of experience and developed a camera system that also meets our own demands for perfection.
These demands are highlighted by the advances we have made in recent years with our cine lenses. Cine lenses – the eyes for Hollywood’s movie cameras – are among the most sophisticated lenses in the world. They generate a photographic image on a small negative or digital chip that is hardly bigger than a fingernail. This image is later shown to audiences in formats as large as the side of a house, often with more than 100x enlargement. Negatives that are recorded with standard still cameras are usually only enlarged 4 to 10 times.
Cine lenses must deliver extremely-high optical performance in many areas: razor-sharp definition, uniform color characteristics of all lenses in the set, high suppression of stray light and internal reflections. Additionally, cine lenses must have extremely high mechanical precision to guarantee exact scaling, long-life sturdy construction to assure full functionality even in extreme temperatures and humidity.
In recent years, we at Carl Zeiss have attained a lofty position as the global market leader for such lenses – both analog and digital. We wanted to make this performance available to photography, not only for a small, elite circle of well-heeled connoisseurs, but for everyone who wants to take breathtaking pictures with maximum technical quality. Our ZM-lenses are the perfect optical tools to attain such goals, and the new Zeiss Ikon 35 mm camera has been.
"Technical Oscar" for the "Variable Prime" cine lenses, awarded in 1999 |
It is always a very time-consuming and expensive process before the newly-developed lens meets the desired level of quality in every aspect. For example, the initial prototypes showed slightly elevated false light levels in several image zones. This is common with many lenses on the market today but these lenses were rejected and reworked because they simply do not meet Carl Zeiss standards. Numerous single steps in lens geometry, surface structuring, anti-reflective coatings and lens rim lacquering (a unique Carl Zeiss development) as well as the optimization of lens element mounts and the use of a highly-absorbent matt lacquer (also developed in-house) enabled us to reduce the level of stray light to well below one percent – the same as with our cine lenses.
Ulbricht sphere used for straylight tests | 
K8 MTF tester with which we test the optical performance of the lenses |
Cosina invested considerably in order to ensure that the lenses could be produced without compromising Carl Zeiss’ high quality criteria. The lenses are assembled under clean room conditions and adjusted and inspected using MTF measuring machines – the legendary K8 tester – made by Carl Zeiss. As a result, Cosina is able to evaluate the image quality of the ZM-lenses with total precision and objectivity. This is decisive in enabling volume production with reliable, consistently high performance from lens to lens – the trademark of ZEISS lenses.
Another key point in the Zeiss Ikon system is the opto-mechanical coupling between the lens and the camera, particularly with long focal length or high initial aperture lenses like the Sonnar T* 2/85 ZM. Putting the high performance of the ZM-mount lenses on film requires high mechanical precision in the interaction between the imaging optics, range-setting mechanics and rangefinder in the camera. For example, the exact focal length of the 85mm lens at short distances must be precisely adjusted for each lens. The rangefinder coupling cam, which translates the axial displacement of the lens’s optical bloc to the camera’s rangefinder, is then precisely adjusted to reflect the actual focal length. The focus position in the image and the adjusted object range are then exactly in tune with each other. These measuring methods have long been the standard at Carl Zeiss. Cine lenses are focused using a precise scale that must also take the exact focal length of the lens into account. In a long-standing tradition Carl Zeiss lenses are individually inspected and adjusted to guarantee 100% conformity to a number of criteria.
All ZM-mount lenses are T*-coated |
Carl Zeiss is world-renowned for products that maintain their high performance standards over long periods of intensive use. This tradition explains why the ZM-mount lenses are optimized for longevity. This is particularly true of the range and aperture setting mechanics. Special construction and machining processes from Zeiss cine technology go into the lenses used in the Zeiss Ikon system. The result of these efforts enabled Carl Zeiss to significantly increase the longevity of the mechanics over other lenses – a fact that was not lost on numerous test magazines around the world.
Our engineers demand the unimaginable from the highly-effective Carl Zeiss T* anti-reflective coating, a “package”, individually calculated and adjusted for each air-glass interface, consisting of up to nine layers per lens element surface. For all intents and purposes T* coating reduces contrast-reducing reflections to negligeable levels, resulting in almost 100% light transmission. The T* coating process has an additional mechanical function – it must permanently withstand all weather conditions. We test the resistance of the coating using mechanical abrasion tests and salt-mist exposure. We simulate the stress of “sandy” wind in the desert or on the beach, as well as the salt air from the ocean. We place T* coated lenses in boiling water to ensure that the coating does not lift. The T* coating is not just a pretty face!
We wanted to create a particularly bright viewfinder image on the Zeiss Ikon camera. This necessitated developing a complex, new optical design.
The Zeiss Ikon camera will not only impress you with its technical excellence, but also with its ease of use. To meet and exceed the exacting demands of experienced photographers we integrated an AE lock that is particularly advantageous and fast in tricky exposure situations. Targeted exposure corrections are thus simple, swift and intuitive.
The geometry and feel of the camera housing also play an important role. They are impossible to predict on the drawing board. Analysing cameras acknowledged by a wise range of users over many years to have excellent feel, to fit comfortably and efficiently in the hand, we created and tested dozens of prototype shapes – round, square and everything in between before settling on a geometry that unites the wishes of both the Asian and Western cultures.
Zeiss Ikon camera on the shaker for testing mechanical robustness | 
This Zeiss Ikon camera just came out of the freeze chamber with -20° after 12 hours |
During the prototype test phase, the Zeiss Ikon camera had to endure the most rigorous environmental conditions. After all, Carl Zeiss owns the most comprehensive environmental simulation lab in the entire optical industry. Remember that we produce camera and cine lenses not only for our civilian partners, but also optics for space, aerial photography, border surveillance and national defense and we must be able to test our products, especially those for military applications, under the toughest conditions. Whatever the conditions – salt water, impact, dropping, shaking, vibrations, tropical rain, desert heat, artic cold, the cold of deep space in a high vacuum, even rocket launches and tank shells – we can simulate it.
But a test, however difficult, is only a simulation. Many improvement possibilities came to light in this phase – just as we expected. But the most significant test is the photographic trials conducted by real photographers under all sorts of real conditions. Their input has been analysed and discussed, their suggestions carefully considered and incorporated (or sometimes rejected). What we can guarantee is that the improvements discovered during the development and testing phases will be included in volume production. Even though this will result in a slight delay in delivery of the camera to market, we are absolutely convinced that this minor inconvenience will be seen by our potential clients worldwide as worthwhile in the pursuit of Zeiss Ikon quality. After all, we want to get the most out of the Zeiss Ikon system just as much as you do.
Zeiss Ikon has been legendary through most of the history of photography. Our goal in the 21st century is to create once again a reference for film-based 35 mm rangefinder camera systems. The Zeiss Ikon with its unique ZM-lenses will surprise you.
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