Robots to Hand Polishing: 10 Facts From Canon's L Lens Factory

[Ah Keong]

Sci-fi style robots, fault-hearing engineers, anti-static shoes – Canon's Utsunomiya lens factory is a hotbed of innovation and precision. Canon's L-series lenses are known around the world for their professional-quality build and sharp results, but to produce such outstanding lenses requires impressive levels of craftsmanship, attention to detail, and a few surprising practices.

From the bespoke machinery that perfectly moulds the glass, to the engineers who hand-test the lenses, nothing is overlooked. Here, we uncover 10 top facts from Canon's lens factory in Utsunomiya, Japan, that highlight the craft behind these pro-level lenses.

https://www.canon-europe.com/pro/stories/l-series-lenses-facts/

1. Japanese engineering is everywhere
2. Lens experts can hear faults
3. Lens polishing tools are made with diamonds
4. Aspherical lenses are made by melting glass
5. Sci-fi robots roam the factory
6. Lens polishing machines self-correct
7. Lens measurements are incredibly precise
8. The hardest lens to make is.... (see answer below!)
9. The innovation never ends
10. Canon lenses could (probably) cover half the world

Is building the widest zoom lens in the world the greatest challenge? The Canon EF 11-24mm f/4L USM lens – which offers an angle of view of 117° at its widest setting and has a huge convex front element, with four aspherical elements – might appear to be the most difficult lens to make, but Toshi says not. "It was a slight challenge at the beginning, but not so much of a difficulty." In fact, the hardest lenses to make are Canon's long L-series telephoto lenses, such as the Canon EF 100-400mm f/4.5-5.6L IS II USM. With their complex internal movements, they are the most time-consuming to assemble – taking four times longer than zoom lenses such as the Canon EF 16-35mm f/2.8L III USM.