A very popular East German system that originally consisted of two competing lines of 35mm film SLR cameras: the CONTAX developed by Mechanik Zeiss Ikon VEB Dresden and the PRAKTICA developed by VEB Kamera-Werkstätten Niedersedlitz. Both companies subsequently became part of VEB Pentacon Dresden. It is to these cameras that the world owes the appearance of the M42 screw mount, which became universal and was used for several decades by many major camera and lens manufacturers, including but not limited to companies such as Asahi (Pentax), Fuji Photo Film, Mamiya, Olympus, Ricoh, Rollei and Yashica.
A fairly wide range of lenses was produced for this system, and the main manufacturers were companies such as Meyer-Optik (Pentacon) and Carl Zeiss Jena. In addition to the M42 screw mount, many of these lenses were also available with the Exakta bayonet mount, and some of the Meyer-Optik lenses - with the Praktina breech-lock bayonet mount.
Most lenses had a fixed mount, but models such as Orestor 135/2.8, Pentacon 135/2.8, Orestegor 200/4, Pentacon 200/4, Orestegor 300/4, Pentacon 300/4, Orestegor 500/5.6, Pentacon 500/5.6 and Spiegelobjektiv 500/4 had to be used with an interchangeable adapter.
In the Western Bloc market, Carl Zeiss Jena lenses were sold under the name "aus Jena" (which means "from Jena"), since the right to sell lenses under the Carl Zeiss trademark in this market was granted by the court to the West German company Carl Zeiss, located in Oberkochen.