
Posted: Mon Apr 18, 2016 11:14 pm
Some of the mystery is solved, at least on the historical side.
From this website [url]
https://translate.google.ca/translate?hl=en&sl=de&u=http://photobutmore.de/vintagephoto/filter/hersteller/&prev=search[/url]
(Please forgive the poor translation)
Kelpan was a brand of filters that was born of, Pan Ortho, a filter manufacturer in the 1920s
By 1945, Pan Ortho started selling filters under the brand name "Kelpan" and continued until the 1962, when the company was bought out by Heliopan
Contrary to the eBay posting I found, Kelpan was not directly associated with Ziess.
As far as my project is concerned, this appears to fit the history of the camera (Manufactured in 1938-1939, purchased in 1939, and used by the original owner until the 1960s. So knowing the history is great, but finding specifics about the filter, and other Kelpan filters made in the same time period, is going to be a bit of challenge.