Historically, who originated the convention of front-of-lens filters measured in millimeters?
From a casual search looking at photos in Wp etc.:
General discussion of filters appears to suggest that they were popularised by Kodak (i.e. Wratten etc.), but they would hardly have used mm sizes.
Some 1930s Leica lenses look as though they had threads, but not all.
The Ihagee Kine-Exakta from the late 30s appears to have provision for threaded filters.
Can anybody quote "chapter and verse"?
I'd add that in the past I found myself measuring the non-standard threads expected by some Olympus supplementary lenses for a "bridge" camera, and while I got some weird diameters (CLA-12 45.6, TCON-17 54.7, CLA-11 56.8mm) they were still uniformly 0.75mm pitch.
