The postwar 35/2.8 Biogon was a lens constructed of seven elements in four groups. In 1954 Zeiss marketed the 35/3.5 Planar, a slower lens of simpler design, to reduce the cost. The Planar is a five element in four groups design. It has a twin diaphragm, allowing it to stop down to f/22. It was not a popular lens as it had a reputation for a inferior performance, although it is supposedly a fine performer. About 5000 were built.