Zeiss Planar
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The Zeiss Planar is a photographic lens designed by Paul Rudolph (physicist) at Carl Zeiss in 1896. Rudolph's original was a six element symmetrical design.
While very sharp, the lens suffered from flare due to the large number of air-to-glass surfaces. Thus, it was temporarily pushed aside in favour of the Tessar, a simpler, four element design. While it delivered slightly inferior image quality, the Tessar was much less susceptible to flare due to its fewer air-to-glass surfaces. In the 1950s, when high-quality lens coatings became available, the Planar was taken up again and its flare problems were solved. This enabled Planar-formula lenses to dominate the normal (50mm) to short tele lens category.