I had to ask the KGB to pull this up from their archives.
f2.0 50mm Jupiter-8/8M These lenses were seen on M39 screw, and as Jupiter-8M when on
Kiev, in 1963, 1975. This is a common lens, based on the Sonnar. These were made in chrome or black finish,
when the number may be on the side of the barrel and here it does not seem to begin with digits suggesting
the date- the Kiev lenses do seem to, eg. at No 7,468,32x on body 7,410,53x. but the M39 ones include one
seen at No0,223,64x in black, 7,418,73x in chrome. (Rus004). Others may have the date, as with
No5,942,769, which is a 1:2 F=5cm in a rigid white barrel, with unuasually a protruding finger knob at the side
for focusing. Alderson in Photographica gives 1957 as the date for the conversion from the Jupiter 8 to the
Jupiter 8M which was used at least on Kiev bodies until replaced by the Helios 103 about 1980. (The
additional coding M may show improved coating as the external curves of 8 and 8M lenses seem to be the
same or not measurably different.)
Note that at least one camera, the TSVVS used original Zeiss Jena f2 Sonnars, eg at No3,060,22x.
11 and 13 blade apertures were very common possibly until auto exposure modes were introduced.