The Industar-22 design was "borrowed" from Leitz Elmar. It was an improved version of a prewar collapsible FED lens (also known as Industar-10).
The Industar-22 was a standard lens on the early Zorki cameras (Zorki, Zorki-C, early Zorki-2C) and was also a popular enlarger lens in the USSR.
This type K380 is always marked on the faceplate with "5cm".
The first digit of the serial number is a year prefix (5=1955, 6=1956, 7=1957, 8=1958).
In most combinations the knurling of the lens was matched with the knurling of the wind and rewind knobs. The pictured knurling can be found on later Zorki-C, straight stripes on early Zorki-C.
Fotoua: KMZ type 4d and type 4c (pictured)
Focal length: 51,39mm
Angle of Coverage (35mm film): 46°
Focusing: 1m - Infinity
Aperture markings: from 3.5 to 16
Optical Design: 4 elements in 3 groups
Optical registration (back focus):28.8 ±0.02mm
Mount: M39x1mm. The lens mounts and RF couples with any Leica or Leica copy (FED, Zorki etc.)
Filter size: 36mm slip-on type
Finish: Polished chrome, Matte chrome