Not sure where to put this but this is a link to a 7-minute tour of the Sigma factory...https://www.cinema5d.com …fp-camera-35mm-lens-soba/
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Seeing the inside of these manufacturing facilities is an amazing treat. I was privileged to spend about two weeks in Japan in the early 1980's and at a time when I had Konica equipment. My host, who had a brother who was a VP of Konica, happened to note my gear. On the afternoon before leaving Japan I was treated to a tour of the Konica factory. I was told I could not have my camera with me so it was turned over to security. At the end of the tour a 35-70 f/3.5 Hexanon AR had been mounted to the Autoreflex T4 body as a gift. That became my main lens for many years although the Autoreflex body and lens was very heavy.

