Zenitar

Zenitar () is a series of Soviet/Russian prime lenses. They were developed and are currently produced by JSC S. A. Zverev Krasnogorskiy Mekhanicheskiy Zavod (KMZ). The series is most commonly known for the 1:2.8 16 mm fisheye lens.
The lenses can be used with cameras using the M42 lens mount as well as with other mount systems using an adaptor ring. They can also be equipped with a Pentax K mount since the flange-film distance is identical.