Leica Produced the 50mm rigid 1:2 Summicron screw mount from 1960-1962 code named “SOSTA.” The total production of screw mount Summicron lenses numbers 59140 units. Of that number, only 1160 of them were the non collapsible mount. For around a decade during the 1960’s-70’s Leica offered conversion of SOSIC and SOMNI 5cm 1:2 Summicron’s to screw mount by removing the lens head and applying a screw mount to that head. This conversion essentially created a “SOSTA.” These converted “SOSTA” lenses did not have matching serial numbers on both the lens head and screw mount, but rather had differing serial numbers since Leica used spare parts to convert the M mount Summicrons.
The 50mm 1:2 rigid Summicron SOSTA that we have in our collection is one of the original 1160 that were manufactured. This lens has matching serial numbers on both the front of the lens as well as inside the lens mount. We have rated this lens at 9 out of 10 and priced it at $2795.