
An in-depth tour of Nikon’s Hikari Glass factory - sohkamyung
https://www.imaging-resource.com/news/2018/04/17/glass-for-geeks-an-in-depth-tour-of-nikons-hikari-glass-factory
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jakecopp
> ...the general shape of this diagram calls to mind the shape of the Japanese
> archipelago, so Japanese optical engineers will often refer to a type of
> glass as a region of Japan. For instance, if an engineer is looking for a
> glass with low Abbe number but high refractive index (the extreme upper
> right of the diagram), they'd say they're looking for a "Hokkaido" glass.
> (Hokkaido is Japan's northernmost island.)

I found this a wonderful little detail that shows the humanity of the factory.

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geerlingguy
> It looks a bit like a map of the Japanese islands, so optical engineers will
> often talk about "Hokkaido", "Tokyo" or "Nagasaki" glass.

It is interesting; I wonder if (especially since so much of the glass in
optical devices comes from Japan) these terms are pretty universally-applied
in the lens-making industry. It's one of those things that makes perfect sense
once you've seen both the chart and a map of Japan... but if not, you'd be
quite puzzled.

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buserror
Interesting the comments about the bubbles being detrimental to the optics.
For most of last century, having bubbles in the lens elements was actually a
sign of a great lens! It was eventually narrowed down on how the glass was
cooled (confirmed by this article) and it seems the slight change of
refraction was largely compensating for the bubble(s).

I've got some early, pre first world war lens that are absolutely amazing
optically, bubbles and all. I've also got one Tessar 4 element lens in
particular, on a pre 1936 (uncoated) Zeiss 6x9 Folder that is just out of this
world in sharpness.

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dekhn
High quality glass making has a long history and it's only been the last
50-100 years that Japan has climbed up the tall ladder to become a world-class
glass manufacturer.

Some of the most important science ever done was done using German lenses by
French scientists (the germans didn't have the scientists, the french didn't
have the lensmakers) - 2+ meters lenses used to concentrate light to burn
metal in evacuated chambers. Eventually, Germany developed its own industry
and science center around glass (Jena) and became the world's leader in high
quality lenses (late 1800s).

In the US, it was Corning that did this work. They did melts and cools that
lasted months to make the blank for the great Caltech telescope in the 20s or
30s.

it all comes down to the frit.

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brudgers
The image that struck me is the tree senior executives comfortably dressed not
in golf shirts or suits, but in practical work fatigues.

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dylan604
What struck me is how everyone is clearly very senior (in age) looking, or at
least how nobody looks young. Are there no apprentices/journeymen type of
up&comers? I haven't had a chance to read the full in-depth article, so maybe
that is mentioned, but this looks like one of those jobs that probably doesn't
attract a lot of interest from the younger generation.

~~~
sohkamyung
I think there are (young) apprentices. But some parts of the process probably
requires years of practice and experience before they are allowed to work with
minimal (or no) supervision that only 'older' people appear at those stations.

An example from the article:

 _I asked Arai-san how the press-operator knew how long to apply the forming
pressure, and he replied that there were three factors: 1) the softness of the
glass, based on its appearance, 2) how the glass feels while pressing it, and
3) how the glass feels when it drops from the mold. I can imagine that it
takes a lot of experience, to be able to take all these cues into account, to
produce perfectly-pressed preforms!_

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toomanybeersies
It's interesting to see how manual the process still is.

I would've thought for something like manufacturing glass, you would be able
to make the process more or less entirely automated.

~~~
geerlingguy
I'm guessing this is the main reason lenses like the 600mm f/4 FL VR are
$12,000+ (probably every element is handmade/inspected), while cheap plasticky
lenses like the 18-55mm f/3.5-5.6 VR are $100 or so.

My guess is the cheap lenses are fully automated, using fewer actual glass
components, without features like 'ED' glass which requires all these extra
manual processes and firings.

~~~
wtallis
There's a _lot_ that separates a cheap 18-55mm kit lens from the super-
expensive telephotos. But probably the single biggest factor is that the 600mm
f/4 requires much more glass and in much larger pieces, so even with the same
target for optical quality you would expect to have much lower yield and
higher manufacturing costs for the massive telephoto than the pocket sized kit
lens.

It's probably more interesting to compare the differences between two lenses
of similar focal length and aperture. With that kind of comparison, the kind
of differences that you'll find are that the more expensive lenses tend to
have metal instead of plastic frames, may have optical stabilization in the
lens, fancier or faster autofocus systems, better sealing against water and
dust, and more advanced coatings on the optical elements. In terms of the
glass itself, you will also generally find that the more expensive lenses use
more optical elements with potentially more complex shapes (eg. aspherical
elements) to reduce distortion, so they tend to have more glass than the
cheaper lenses. Given how many other factors contribute to the price
differences, I doubt that you actually find order of magnitude differences in
the price of unground lens blanks of similar size destined for cheap vs high-
end camera lenses.

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tomn
This was really interesting -- not a process I've ever realy thought about.

You might enjoy this, Ben Krasnow talking about the challenges of making
photochromic glass:

[https://www.youtube.com/watch?v=mUcUy7SqdS0](https://www.youtube.com/watch?v=mUcUy7SqdS0)

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baud147258
I've enjoyed reading this article, showing the process to fabricate just a
glass lense.

The site has other articles like that one, but only related to cameras. Does
anyone know of similar article, but for other industries?

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jakecopp
> The finished preforms are packed in vinyl trays, with a number of preforms
> in each carrier - at least for smaller lenses like these. I imagine that the
> huge front elements for the like of a 600mm f/4 might call for more robust
> packaging.

It looks just like a muffin tray, though each muffin is a lens element!

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creo
At first i was like: "In-depth, yeah, right ...". Then half way in the
material i found myself confused with how much information was delivered.
Great work!

