According to Thiele's book, this lens was manufactured in 1914 for the camera on a balloon. So it might be used for the military survey.
It is a 3 elements triplet lens and can cover 3 1/2 x 4 3/4 at full aperture according to Voigtlander catalog in 1914.
Here is the catalogue list for the Helomar (PRochnow book).
Only the two largest versions have an iris.
The Heilomar was the basic lens on the early voigtlander Bessa rangefinder. This cameras was the all black version before the chrome bessa ii was produced.
I have one with the heilomar, but the focus of pretty tight so I have not had a chance to use it yet.
Steven, the catalog page you posted seems to be for narrow angle projection lenses, not for taking lenses. Am I mistaken?
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