Зоркий-4K , Zorki-4 is a 35 mm rangefinder camera, manufactured by Krasnogorsky Mekhanichesky Zavod (KMZ) , (Красногорский механический завод = Mechanical Factory of Krasnogorsk), near Moscow, former USSR and produced between 1956-73, quantity 1715677. ЗОРКИЙ = Zorkiy, means Sharp Sight. Lens: Zorki-4 was supplied with either a Jupiter-8 (ЮПИТЕР) 50mm f/2, or Industar-50 (ИНДУСТАР) 50mm f/3.5 lens; several other lenses were available. The lens is interchangeable, M39 screw mount From Wikipedia: The Zorki 4 was possibly the most popular of all Zorki cameras, with 1,715,677 cameras made by the KMZ factory in Krasnogorsk, Russia. The Zorki 4 was also the first of the Zorki cameras to be exported in large numbers to the west. It is a fully manual camera, and does not have a lightmeter. An additional lightmeter may be added by the cold shoe. When the Zorki 4 rangefinder was introduced in 1956, its contemporaries included the Zorki S, Zorki 2S, FED 2b, Leica M3 (introduced two years before), Leica IIIg, Nikon S2, Canon VT, and Canon L1. The Zorki 4's production run outlasted all of them. When it morphed into the Zorki 4K by 1973, its contemporaries included the FED 4b, Leica M4 and M5, Nikon F2, and Canon F-1 and Canon Canonet QL 17 GIII.