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Design and structure of high-performance zoom lenses for 35-mm photography

The development of the 35 - 70 mm f/3.4, 80 - 200 mm f/4, and 28 - 85 mm f/3.3 - 4 Vario- Sonnar lenses for the 24 X 36 mm format has been centered on finding means of design which ensure image quality equivalent to or at least approaching the image quality of fixed focal-length lenses. The structure and the performance of the lenses are described, and the development process of the Vario-Sonnar lens with focal length doubling is discussed in greater detail.