Years ago, I bought a copy of a Canon-sponsored movie titled Bending the Light.
It runs 1-hour long, and it has different chapters in it. Lens manufacturing was prominent in it.
Bending the Light is now available to see on YouTube, at no cost, at least in the USA:
Thanks for posting these. I've always enjoyed seeing how things are made (it helped that I worked in manufacturing for years); even better when it crosses paths with a hobby.