The Leitz Wetzlar Summarit 1.4/50 lens is an authentic, original factory prototype. It stands out from later iterations in several key aspects. Firstly, its E41 Filter size differs from the standard E43mm found in the serial production Summilux lenses. Notably, this prototype incorporates an infinity-lock feature of a unique design, with the infinity index positioned to the right, while the lock and diaphragm index remains at the 12-clock position. Furthermore, the lens mount exhibits distinct differences compared to later models. Internally, it bears the engraving '0000189', the Leitz factory records the lens no.0000189 as a Summarit 1.4/50. No other example of this lens is known to exist. Additionally, the included metal lens hood is tailored specifically for the E41 filter size, a characteristic exclusive to this lens. Notably, other prototype lens hoods exist for Summarit lenses with an E43mm filter size, constructed featuring different materials and finishes. Included with this rare lens is a written expertise from L. Netopil. It is for sure one of the most special lenses we have seen.