Bausch & Lomb Tessar licensing.

Does anyone here know when approximately B&L Tessars stopped being marked with the Zeiss name? I have heard prior to WWI but am not sure how accurate that information is. I've also heard that the serial # blocks used were all over the place and lenses in the 2,000,000 range have been found from the 30's-40's and others from much earlier. I'm looking at a 5x7 1c which I believe to be 190mm base on this chart. http://www.allenrumme.com/lensdb/Bau...and%20Lomb.htm The exact lens I'm looking at is marked "5x7 Bausch & Lomb Zeiss-Tessar Series 1c." The serial number is 1,413,573 which according to some unnoficial B&L serial # charts I've found is way beyond any recorded range before they went to the lettering system. According to another source the Zeiss-Tessar marking was dropped when Zeiss stopped licensing the Tessar design to B&L sometime prior to WWI. Just kind of curious how old this lens may be. Thanks in advance for any info.

I believe the serial number lists are controversial for accurate dating. In 1892 they were licenced to make Zeiss lenses. According to The History of Foreign Investment in the United States, 1914-1945, Zeiss sold it's interest to the B&L family prior to America entering WWI (1918).

And this http://tedbrink.webs.com/usabauschlombstory.htm: "Bausch & Lomb's arrangement with Zeiss unraveled after the outbreak of World War I. The company had sold the Allies equipment without Zeiss's approval in Europe, which was not one of Bausch & Lomb's markets. In 1915 Zeiss sold its 20 percent share back to Bausch & Lomb, and until 1921, the two companies had no dealings with one another (although Bausch & Lomb continued to use Zeiss patents). " I'm looking for a reference, but would say by 1915 they started making their own glass (previously it was imported from Germany), and had no Zeiss investment, so there is a good chance at that date they stopped putting "Zeiss" on their barrels.

Based on Zeiss Kodak Anastigmats (Tessar Ics and IIbs) made by B&L for EKCo, B&L last used the Zeiss name in 1915.

Kyle, go to the horse's mouth, not to Allen's lists. Visit www.cameraeccentric.com, which has many B&L catalogs.

Thanks to both of you.

Not an answer to your question, but you can read about the partnership in this book as of 1908

https://books.google.com/books?id=fP...0zeiss&f=false

Dan