Clueless said:
I sure hope you know that it was for 6X9 and not 4X5. It is often "presented" as a conventional coverage of 4X5 since it is a 150, but the official literature with its high standards pegs it at 6X9.
What official literature specs the 150 Apo-Lanthar as a 6x9 lens?
I have two original product brochures, and both list the format as 9x12 cm (one also gives the inch format 4x5).
The 10.5 cm focal length is for 6.5 x 9 cm.
The Voigtlander brochure "Apo-Lanthar" appears to have a date code of 1958. The Zeiss Ikon / Voigtlander brochure "Professional Lenses" appears to have a date code of 1967.
The first brochure is unique for acknowledging the thorium content: "These glasses contain the rare elements lanthanum and thorium, important in the atomic energy industry, and from them the name APO-LANTHAR is derived." Most manufacturers using lanthanum and thorium preferred to mention ony the former -- see (there was a url link here which no longer exists)