Canon’s 500mm F/4 L IS II Lens is a $10,499 behemoth. It is a second generation of the 500 f/4 L glass, following a v1 stabilized unit. Both are considered top of the line lenses.
It is amazing to see that part of the production process includes manually crashing optical glass by hand. Than on the other hand, after the glass has been ground and polish it is handled with care saved for diamonds.
If you want to cry, jump to 8:46 where you see an entire tray of the front element simply sitting on a cleaning table.
P.S. unsurprisingly, Lee Filters are going through a similar process