I have been pondering on the relationship between the inventors of Rondinax tanks, the manufacturers and those who sold them under their brand, namely Agfa, Leitz, Johnsons of Hendon and Neville Brown.
This post, in a way, extends the information shown in the separate Page (see Menu above) on Patent History.
On reading what I can about Michael Lesjak, I am coming to the tentative conclusion that neither he nor Wilhelm Kehr were employees of Agfa.
Let’s first consider Michael Lesjak. Apart from his 25 patents, for which Espacenet is invaluable, Google searches are not very fruitful. However, starting in 1920 he invented a new way of packaging photographic plates so that they did not become scratched whilst being changed. A number of international patents cover this invention and it is mentioned in a few photographic histories from continental Europe.
Here is the heading of the British patent and the start of the description.
Note he is described as Photographer.
In 1922, with Friedrich Egg, he invented a toy carousel, suggesting he was a private inventor rather than a company employee.
Before the invention of what became the Rondinax tanks, there are two German patents, again granted to Lesjak and Kehr, that describe a side-loading developing tank with a slit and sealing device. The applications were made in 1932 and the patents were granted in 1933.
I now wonder if those patents were the precursors of the patent granted to Optochrom (also from Augsburg) in 1936 from an application made in 1934. The principles are not dissimilar. Was there a close relationship between Lesjak, Kehr and Optochrom (by then manufacturing its glass filters)? All the parties were located in Augsburg. I would like to find out who the shareholders in Optchrom were.
In 1950, I can find mention of a Michael Lesjak of Augsburg being Secretary of a flying club set up as soon as the Allies permitted their formation in the aftermath of the Second World War.
By 1953, a patent granted shows that Michael Lesjak had died. Whether or not he had died by the time the patent application was made (late 1950) or amended (1951) I cannot tell.
Overall, my impression is that the intellectual property was licensed by Lesjak and Kehr (Kehr was involved throughout in the invention of daylight-loading tanks) to Agfa for the production of the Rondinax tanks before and after the war. Did they make separate licensing deals with Leitz (in association with Agfa)? How did Johnsons of Hendon and Neville Brown (NEBRO) obtain the rights to manufacture Essex and Kent tanks in Britain after the war? Was it by a direct deal with the inventors or were Agfa also involved since they may not have been in a position to export or even manufacture tanks at that stage? Agfa was certainly having its problems after the Second World War. It was a constituent company of I.G. Farben which was being broken up by the Allies because of its close involvement with the Nazi regime and the production of Zyklon B for killing millions of people in the extermination camps. The fate of Agfa was not finalised until 1952 (Opting for Oil: The Political Economy of Technological Change in the West German Industry, 1945-1961 by Raymond G Stokes, Cambridge University Press, 2006).
Further information would obviously be very welcome.