Roman Urban -Tosogu.Cz

Lenses in Japanese Metalworking: Tradition or cheating?

During my praxis I have come across many times the opinion that optical devices such as a microscope does not belong to a traditional craft. And that using such a device is actually cheating, because Japanese craftsmen did not use anything like that. So I tried to put together historical facts and personal experience, and summarized them in this article as an attempt to explain that optical devices definitely belong to the traditon of Japanese metalworking. It is said that Japanese craftsmen were short-sighted and therefore were able to work without magnifiers. This may be partially true. Children from the age of about 5 were employed in goldsmith workshops (Similar praxis was in European workshops too.), first as assistants, and later the most skilled could become specialists in a certain type of work such as nanako production. A healthy eye of a young person is able to focus from about 6.5 cm to infinity. This minimum distance gradually increases with age and predispositions. By the time I became interested in this fact, it was already an adult, my focus point was about 18 cm. Now, after 45 years of age, it is almost double, about 30 cm.

It is said that specialized manufacturers did not even need to look at a punch, but moved it with a hand feeling over the already formed bumps. However, creating nanako also requires very sharp eyesight, and without it, this work is not possible. The finest nanako balls are about 0.2 mm in diameter. Holds true, that the finest is a surface structure the more is each mistake visible. A maker must see and examine quality of his execution. Without a sharp sight is not able to do such work.

From the experiments I did more than 10 years ago, I know that if a craftsman has an eye of about 7-8 cm from the object, he is able to see and work without any magnifying devices, even on finer ornaments. So basically short-sighted craftsman had some advantage. Although the human eye has its limits in this regard as well.

As the distance of the eye from the object increases, the ability to work decreases rapidly, 30 cm from the eye you can see practically nothing. It’s enough for rough work, but not for detail. The discovery of dioptric reading lenses enabled craftsmen to work not only at a later age, but also on much more delicate details. Books from the second half of the Edo period show artists and experienced craftsmen, almost all with glasses.

One of ways to work with a magnifying lens.

Reportedly the oldest surviving glasses in the world, (circa 1475) comes from  property of the eighth shogun Yoshimasu Ashikaga (1436-90), who dedicated them to the Daisenin Temple. But this is a temple legend that cannot be verified in any way.

However, it is documented that the first dioptric glasses were brought to Japan by Francis Xavier as a gift to the daimyo ruling Yamaguchi Prefecture in 1551. Later, other missionaries followed his example, and along with other gifts, brought glasses to land rulers as a sought-after items.

It is worth mentioning the first record of existence of myopic (short-sighted) glasses in Japan. It comes from a visit of the Jesuit monk Francisco Cabral in 1570, whom the Japanese nicknamed the four-year-old padre.

Glass production in Japan began around 1620 in Nagasaki, from where it spread to other parts of the country. And with glass also the production of glasses (Aitai) and myopic – lenses, magnifying lenses, telescopic binoculars, lenses for igniting fire using the Sun beam, lenses for observing eclipses and more. The production of glass lenses was handled by optical glass grinders recruited from precious stone grinders. Although glass spectacles did not appear in Japan until the 16th century. Quartz optical lenses have been known for many centuries before. The oldest find from Chinese cemeteries even comes from the 1st century. A.D.

The Magnifying Glass
ca. 1775
Toriyama Sekien

Of course, these modern inventions were not available to everyone at first. During 18th century however, demand increased so much that domestic production was insufficient, and large quantities of spectacles were imported from China. Gradually import was subdued and Japanese production increased to meet the demands of the Japanese population. According to the development, it can be assumed that access to high-quality glass reading spectacles and magnifying glasses was initially only available to metalworkers serving at court. Where the best works of their time were also created with support of ruling class.

At first slow, but during the 18th century. A striking development in the complexity and subtlety of the decoration of the sword mountings is a clear proof of how magnifying lenses began to be applied on a larger scale, and the present invention allowed work with breathtaking detail.

Some may argue that no evidence (eg  painting) has been preserved that goldsmiths-kinko in 17-18th century used magnifying lenses. I think that paintings of the time where craftsmen would be ever captured at work would be rather rare, and I personally have no idea about theit existence. Art was reserved only for the upper classes, and they were not interested in the common people. Craftsmen and farmers began to be displayed in 19th century by painters like Katsuchika Hokusai and others. Alternatively, neither proof of the preserved goldsmith’s workshop 17-18th century with equipment survived. However, I cannot exclude their existence. On the contrary, the existence of optical instruments in their time is unquestionable from written records. And it was the metalworkers-kinko who, thanks to magnifying lenses, began to produce special fine surgical instruments that would not otherwise be possible to manufacture.

But the development has continued to present days, when metal engravers use stereo microscopes quite commonly. Yes with a simple lens you can do the same work, but the craftsman who makes a price offer to a customer, must be also able do it in  reasonable time. Working with an engraving microscope (which is de facto only improved reading glasses combined with a magnifying glass.) is much more efficient. Larger field of view, stable and sharp image without distortion, they are also more gentle to your eyes.

At all times, people have always tried to make their work more efficient. Therefore, hoists and cranes began to be used in construction, magnifiers in watchmaking and goldsmithing, wheels in transport, electricity in communication etc.

Progress has not stopped, but they are all only helpers. The core of all art and tradition is in the hands and minds of man. Nothing will do his job for him. The idea does not materialize itself, the painting does not paint itself and the ornament does not engrave itself.

The History of Ophthalmology in Japan – Saiichi Mishima, vyd. J.P. Wayenborgh, 2004
Journal of Astronomical History and Heritage (ISSN 1440-2807), Vol. 11, No. 3, p. 203 – 212 (2008)
Spectacles and Other Vision Aids: A History and Guide to Collecting – J. William Rosenthal, 1996