West-Germany: ZEISS IKON AG: 1953-1972:

The west-german branch of the Zeiss Ikon brand, built up in Stuttgart after the war as the "main office", had problems realizing what was going on in the new camera world as not only the east-germans, but italians, swiss, hungarian, british and even french cameras were ahead of them in the field of eye level slrs. Their answer initiated a wave of not so good looking, heavy cameras with a central shutter in the lens. Most west-german brands followed this trend, Wirgin Edixa being the only one to chose another path. So, if they could not make the best cameras, their policy to get big marked shares in Europe, was to hunt down the east-germans by law suits that forced them to change camera name from Contax to Pentacon, and lens name from Carl Zeiss, Jena, to CZJ or just Jena, or Pentacon, among other names. All kinds of obstacles were set up to keep the east-germans out of western markets, and with full support of the real commanding officer, the US administration. To discredit the east-germans further, even the M42 mount, born with the Contax S and the Praktica, was named Pentax mount in the west, as Pentax had adopted the mount and spread it among other brands.
For a relatively short time, this policy was rewarded with high sales for west-german brands in the west. Zeiss Ikon AG had released the Contaflex in 1953, and it was a leader in the west for some years, until sales dropped and production was stopped in 1968. ZI AG had for long been lacking the technology of the japanese, and even lost against the remaining east-germans, i.e. Praktica.

Presented in 1958, with start of production in '59 and generally available from 1960, Zeiss Ikon AG came up with a camera that was meant to knock out the competition among the pros, namely the Contarex. It was ugly, heavy and very expensive, and still had no IRM. Quality was good, a variety of high class lenses were offered with it, as ZI finally understood the shortcomings of the leaf shutter. But the Contarex was no big success, and was only produced till 1966.

Most west-german brands went out off business during the 60s, and Zeiss Ikon were loosing, too. What had been earned through many years in leading position, got wings to fly with as developing and production costs by far surpassed sales income.
In 1965 Zeiss Ikon AG merged with, or finally took over Voigtländer, after some 10 years as minority stock holder. Voigtländer was just developing a couple of interesting models at the same time. Bessaflex was a more modern camera than Contaflex, and could have been the news that ZI needed. But the plans were put aside.
Instead, another Voigtländer construction was released, the Icarex in 1966. That was going to be the ZI camera until all camera production was ended in 1972.

But the name was not dead: Zeiss went into a co-operation with Yashica of Japan, and in 1975 the Contax RTS was born!

Although developed by Voigtländer, the introduction of the Icarex 35 had to wait until after the merger with Zeiss Ikon in 1965. The Icarex was the third in the row of PP SLRs form Zeiss Ikon AG, and introducing the third mount. This, of course limited the variety of lenses. So, in 1970, ZI introduced an Icarex with M42 mount, but it did not help. Production of the Icarex was terminated in 1971.

Knocked out by the japanese smaller, lighter, technically more advanced and less expensive cameras, Zeiss Ikon AG in West-Germany finally had to admit that the hegemony, and the game, was over. Even the east-germans had far bigger success with their Prakticas than the somewhat arrogant big brothers in the west. The people at VEB Pentacon in Dresden must have had a laugh as the company that forced them to change names after winning the cases in western courts now had to give up production, while Prakticas were sold in millions.

But Zeiss Ikon didn't quite give up. They admitted that if you cannot beat them, join them.
So, Zeiss went eastwards, all the way to Japan to cooperate. They chose Yashica as partner. 

From 1975, a new Contax was born, the RTS produced by Yashica. Lenses wore the name of Zeiss, Yashinon or Yashica Lens, depending on the price tag.

Yashica also made other Contaxes than the RTS, the flagship.