What kind of lens has aperture scale in mm?

[Havoc]

Hi Dan, thanks for the links, however in my browser there is a starry wheel but without the option to download (therefore non of the pdf's in your listings can be downloaded). Could you insert a direct link to the 1901 pdf - like you've done with the post war II pdf?

many thanks
Ron

If you cannot download, then it is a copyright limitation of where the book is, and where you are. Here in Belgium you can also not download pdf books from Google books. Only way is going through a foreign proxy.

[erian]

For a time -- some time in the 1890s to early 1900s -- Carl Zeiss Jena scaled apertures in mm. See, e.g., the 1901 CZ London catalog, which has an extensive discussion. There's a link to it in the list.

XVIsub1 is very Zeissish. See the 1910 CZJ catalog p. 14, there's a link to it in the list too.

It indeed was a Zeiss lens - 500mm f/4.5 Tessar. The name was under the tape that had been wrapped around the top of the barrel.