FED f2/50mm developed for FED S and FED B factory? .. transformed to Leitz Summar as were various FED transformed in Leicas. Probably 1940 years,
There are at least two versions: white or black front.
Registered serial numbers:
21488------Jacques Morin collection (black).
23814------David Tomlinson (white).
28869------seen on eBay (white)/ Bill Parkinson collection.
28957------David Tomlinson (white).