Before I became interested in working in biomedical research, I was a manufacturing geek. I also lived and worked in a factory in Japan for a year, as part of a US Department of Commerce fellowship. So, naturally, I was interested in seeing a video about the factory that makes Cosina Voigtlander lenses.
This video on YouTube, by Terry Sham Studio, shows much of the lens manufacturing process, as well as some assembly of camera lenses. The audio is in Japanese. My Japanese is rusty (and was not that strong to begin with), but I can get a few of the points. They talk about how actual manufacturing of lenses in Japan (as opposed to China or Malaysia) is pretty rare at this point. They also talk about making OEM lenses for other companies. You can see from this video that Cosina's expertise is in mechanical and optical manufacturing, as opposed to electronics, which helps one to understand why they offer manual focus lenses. You can also see that they produce pretty large numbers of lenses in this factory, with batch processing of components. As always in modern Japanese factories, inspection and testing are an important part of the process.
I found this to be an interesting video. I hope you enjoy it as well.