Filter size for OLD Voigtländer Nokton50/1.5?

[Dr.Kollig]

Yesterday I picked up an old Voigtlaender Prominent I, early series with the Nokton 50/1.5. Filter size is smaller than 46 mm.

TIA,

Wolfram

[David A. Goldfarb]

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.