An exceptionally rare prototype of the Hektor 6.3/2.8cm from 1934, predating the official introduction of the production version in 1935. Pre-war Leica prototypes are of the utmost rarity, as only very small numbers were manufactured for testing and internal evaluation, and the majority did not survive. Surviving examples from this formative development period of Leitz lens design are today of great historical and collector importance.The lens is preserved in good condition, showing only moderate signs of age and handling, with clear optics and well-maintained mechanics consistent with careful preservation. The mount bears the hand-engraved optical formula designation “B236,” a characteristic feature of experimental or developmental examples from this period.Of particular significance, this example is ex Leitz Museum and is accompanied by the original museum inventory card, firmly documenting its provenance. The lens is illustrated in P.H. van Hasbroeck’s Leica in Colour, page 118, further underlining its importance and recognition in the literature.A highly significant and extremely scarce pre-war Leica prototype with distinguished provenance and published reference.