Originally posted by eddie1960 manual K mount lens is no longer subject to copyright control (later A and AF versions are) same with the nikons they made
I'm not sure if the basic EF Mount is Public domain yet, but maybe they just reverse engineered it like everyone else (simpler to since no need to engineer af controls)
Cosina also made a K mount SLR or 2 fully manual (still may actually)
I think Cosina is adapting their business model to more modern realities now (when they started with K mount Pentax had much bigger share and requirements are very similar to a Nikon Manual focus (you can actually make the nikon fit easily with no mods on a pentax body but a small mod will help it lock)
I'm sure you're right about market realities, but the SL versions of the K-mount Voigtlanders were auto-aperture, and the SLII versions also included lens information, so, was there anything else needed to make them more completely like the Pentax A lenses, and therefore subject to copyright or patent control, as you suggest?