Help identify this lens or mount

[filmculture]

Hi, I bought this lens some time ago thinking it would fit a Robot camera. Turns out the mount is too big for Robot, it's about 33mm. I cannot find any mentions of this lens or mount anywhere online. It covers 35mm but film plane is further than Robot.
Any help is appreciated.

 

[Kino]

Probably for a small glass plate camera; possibly a stereo camera.

That would be my guess...

 

[shutterfinger]

A Lens Collectors Vade Mecum has it as a plate camera lens from the 1930's.
Some were used on Exakta also.

 

[filmculture]

Thank you gentlemen. I never knew that plate cameras had lenses with the focusing ring. I should get myself the Vadw Mecum just for questions like this.