One of the most rare portrait lens from one of the most respected maker, Carl Zeiss Jena. Hard to find any information about lens so all information in next lines  just my guess. Made in limited amount from 1936 up to ww2 to did ruin entire Jena factory.
I think lens was launched to Berlin Olympic Games in 1936 as many others from Jena, they had a significant technology jumps in this years, famous T coating, many new cameras and lenses. Lens made for most popular and succesful early German SLR camera Exakta. Lens wide open less sharp than later post-war lenses, pleasant soft what was requirement from a portrait lens in those years when this lens launched. Stopped down to F2 at least or even better more , stunning performet with swirly bokeh. Lens has simple construction , focusing very smooth , light weight , diameter is not huge so pleasant to use.