I know this is an old thread, but I just became aware of it. As far as I have been able to find, the notion that Zeiss made Dagors for only about a year after acquiring Goerz in 1926 originated with Lynn Jones's article some years ago in View Camera.. The following is evidence I've gathered to the contrary (I think I originally posted this on LargeFormat)
Originally Posted by phfitz
"A 1933 Carl Zeiss catalogue on the "cameraeccentric" website lists the Dagor in several focal lengths, both the f/6.8 (the 36 cm is f/7.7) and the wider angle f/9 versions. (This catalogue also shows Zeiss offering the Hypergon.) See:
And I have record of a "Carl Zeiss Jena Goerz-Dagor", 12.5 cm f/9 offered on ebay with a serial number 2,214,759. A Zeiss lens with this serial number would have been made in 1937.
In fact the evidence is that Zeiss was still making Dagors even as late as 1940. A copy of a Popular Photography buying guide I have, dated May 1940, includes the Dagor in several focal lengths in the listings for Zeiss lenses.
Kingslake, in _A History of the Photographic Lens_ indicates Zeiss acquired C.P. Goerz (Berlin) in 1926."
And it looks like Hartmut Thiele's recent references on Carl Zeiss Jena show that Zeiss made Dagors even later than 1940. (Wish I'd taken German for my foreign language requirement, though that would have been nearly 50 years ago if I had.)