I've recently acquired a CZJ Apo-Tessa 45cm with the serial number 2,706,492 .
Since I was interested in it's age I started doing some research and came across an old data sheet which indicates that the first lens design was from 1929 with serial numbers between 3,016,691 and 4,870,945 .
Some other websites date the serial number of my lens around 1941. Obviously this confuses me a ton and I have no idea which data is wrong or right or if even both are correct and I'm just not getting it.
It would be nice if someone could share some knowledge with me so I can understand the origins of this lens.
Coming to this thread about 6 months late. According to Hartmut Thiele's Fabrikationsbuch Photooptik II Carl Zeiss Jena this 45 cm Apo-Tessar is one of a batch of 300, serial numbers 2,706,201 -2,706,500. The design is dated 3 April 1928, production of this batch began 5 April 1943.
Thiele's book is in German, my thanks to Arne Cröll for translating some of Thiele's terminology for me.