I become a crossfield 656 drum scanner operator after seeing ansel dagor prints.
After 10 years of research and entering to internet age , I wrote to Zeiss Archives and asked what do they have in their hands about dagors. They sent two pages scan , prescriptions of Dagor 300 and 350 mm.
After looking , thinking about hundreds of lenses , you can see how dagor design is genius , rafinery and intelligent. At 350 , there are two symmetric group of glasses and a middle air section.
There is no air gap between each glass of these groups and it impress the observer.
I discussed the cooke xv design with cooke head designer and he sent me prescriptions and glass details.
It is now impossible to find every detail of these glasses for these lenses. It is lost.
May be I will buy them , disassemble and send them to analysis. Than copy with sol gel

Mustafa Umut Sarac