Industar-26M prototype lens. Very few samples released in 1959- 1961. Focal length - 5 cm, aperture range f2.8 - f22. Focusing range from 1 m to infinity. Number of elements/groups: 4/3. Angular field - 45º. Leica M39 mount. The glass of this Industar-26M lens has the element Lanthanum in it, to aid in contrast. An ultra rare to find lens.
This guy has some backlash on the focus ring,so full CLA has been applied. Now is ok!