Yesterday I picked up an old Voigtlaender Prominent I, early series with the Nokton 50/1.5. Filter size is smaller than 46 mm.
Colour? We can always use an airbrush later...
Most old Voigtländer lenses had press-on filters. If the thread size is a little less than 46mm, the press-on size is probably 47mm (same as the Bessa II lenses) or maybe there was a slightly larger size, like 48mm. These will be tough to find.
Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com