It's not every day that you get to see behind the doors of a state-of-art factory in Japan and witness first hand how a lens is made. However, we were recently invited to do just that, with a personal guided tour from Sigma CEO Kazuto Yamaki.Mr Yamaki's father, Michihiro Yamaki, founded Sigma in 1961, and the first factory was built on in Aizu in 1974....