It is my understanding that the Leica Lens for the Japanese Leica's are made in Japan, by techs who have been specially trained to work on Leica Lens...
I think that's a myth. I doubt that there is any Leica involvement in the design or manufacture of Lumix 'Leica' lenses, apart from collecting a royalty for the use of the name.
What about Zeiss and Sony then. What are your thoughts on that?
Same thing: I doubt that Zeiss has anything to do with the 'Zeiss' lenses made by Sony, apart from the T* coating they use. Zeiss doesn't design, make or quality control them, just like the 'Leica' lenses on Lumix cameras. It's just a branding.
The supposedly Zeiss lenses on Sony RX cameras are made in the same Chinese factories as the cameras. Some of the interchangeable Zony lenses are made in Sony's Thai camera factories. In fact, Zeiss itself doesn't actually make lenses for still cameras any more, and probably knows less about this sort of lens than Sony does.
Indeed, I think that partnership may even be over. All of the premium new Sony E-mount lenses are now branded G or G Master, not Zeiss. This is Sony's own premium lens brand, going back to Minolta.
These lenses are generally superior to the slightly older 'Zeiss' branded lenses. For example, the new 16-55 G APS-C Sony lens is superior to the old 16-70 Zony lens (which I own), which it effectively replaces. Even the cheaper 18-135 Sony lens beats the expensive 'Zeiss' model.
The new 16-35/2.8 GM FF lens is twice the price, and much better than, the older 16-35/4.0 'Zeiss' lens. The existing Zony lenses remain on sale, but it looks like there won't be any new ones, and they're increasingly being superseded by better Sony G and GM lenses.
