Shoaib Rahman is a specialist in social science and humanity.
At one time it was only possible for the Kings and Empires to capture their own image. The hired portrait artist painted the king's figure with his brush. Today we are taking pictures of ourselves on social media. In between, but many steps have to be taken.
Today's digital images were preceded by color images in the Kodachrome system, followed by gelatin-based black-and-white images from small negatives, followed by platinum prints, egg whites, and so on.
The Daguerreotype will come at some point if the thread of this history goes backward. In a fancy way created by the French artist Louis Daguerre, a picture like magic would be captured on a plate. That Daguerreotype has become a new topic of interest for today's scientists.
What is this Daguerreotype? To get into that story, you have to tweak the "picture" thing a bit first. There are two things behind taking a picture. The light is reflected from the person I am photographing and falls on a screen (in some cases light can come from the object itself, such as the flame of a lamp).
The light reflected from the object in front will go away, other surrounding lights will not be able to enter there. Second, the light will leave a lasting impression on the screen.
The predecessor of Daguerreotype: Camera Obscura
The solution to the first problem is relatively simple. All you have to do is make an alpine-sized hole in a box and aim the box at the scene. As the light travels in a straight line, the light reflected from the front view enters through the hole in the box and creates a reflection of that scene on the opposite side, i.e. on the back wall of the box.
That image will be exactly the same as in the front scene, just inverted. That means head down, feet up. See how it is possible in the picture below. For the success of this camera, it is better not to allow ambient light to enter as much as possible because that light may be reflected on both sides of the box and obscure the image on the back wall.
For example, a cloth canopy can be placed over the box to block ambient light, but not to block the leak.
This is called a pinhole camera or camera obscura. If that were the case, it wouldn't be what we traditionally call a camera, because it doesn't have the stability of a picture. In some cases, it was used only as a shortcut for drawing pictures
Drawing this picture can almost be called cheating. The pencil can be turned over while reading the picture on the screen of the camera obscura without drawing it with the naked eye. In other words, the camera will be a huge man-sized box, a house.
In that room, the artist will sit in ambush. The artist will turn the pencil over the hole in the wall of the room where the picture will be read on the opposite wall. Diameter, the front view was removed, but the picture remained firmly on the wall.
This is the miracle of Louis Dagger and some of his elders. They made that artist useless. Made a plate so that the straight front view would be permanently captured. This is the daguerreotype.
The picture is actually a chemical reaction
Making a good daguerreotype was a matter of skill at the time. Even if you read the manual and make the plate, there was no guarantee that the picture would be as clear as you want it to be. However, the method has documented.
First, a layer of silver will fall on the copper plate, which will come in contact with iodine gas to form silver iodide.
This silver iodide layer is called the photosensitive layer. When light falls, the silver iodide breaks down a bit and a lot of silver falls. The light that falls leaves an impression on the plate through this reaction (coming later in more detail).
Now, this light has to be controlled so that only the light reflected from the front view falls on the plate. But we have already seen how to control the light: the box of camera obscura. You just have to put the plate on the screen opposite the hole in the box.
In this way, the daguerreotype plate sits in the camera box and brings down the front view. This is called exposure. That is, the light reflected as needed fell on the daguerreotype plate.
After exposure, the camera leak is closed and the plate is removed to a dark room. But still, nothing can be seen on that plate. The plate is then exposed to mercury in a gaseous state. The gaseous state of the mercury on the silver lumps solidifies and forms a silver-mercury mixture. This time the picture can be clearly seen on the plate.
Does the rest of the work so that the picture is no longer exposed. That is, no new chemical reactions occur even when new light falls. The plate is dipped in a sodium thiosulfate solution to wash away the remaining silver iodide.
This is called fixing. The picture was firmly captured on the plate. Finally, a thick layer of gold is placed so that the image looks clearer, more durable.
What exactly remained in the last picture?
After so many incidents, what is lying on the plate of the picture is silver-mercury nanometer-size granules of various sizes. In some places it is cluttered, in some places, it is scattered. If an ant the size of a nanometer were to ride on a plate, it would have to climb many mountains (this is not the case with ants, the average size of Daewoo ants is a million times the size of a nanometer).
But we cannot see them with the naked eye. What I see is a picture. That he is not the picture, the scene in which the plate was exposed, is exactly his copy.
How did it happen? The logistics for that research did not exist in the nineteenth century. It was a reaction when the light fell, and when the rest of that reaction was set firmly when the light fell on this new picture, the previous scene caught the eye, that was enough.
But now that research is possible. Some scientists did that research in collaboration with the Metropolitan Museum of Art .
The purpose of his research is not only to unravel the mystery of the one-time camera but also to have some modern applications. The point is to do this: a rough metal surface, where the bumps are nanometer-sized, and how the light will spread if light falls on it.
Scientists went out to find answers to all these questions, such as where there would be bluer in the scattered light, and where there would be redder.
Usually, when we see something colored, it contains some pigment. That pigment absorbs some colors of light, that is, absorbs some wavelengths or wavelengths of visible light, so what we see is a mixture of light of the rest of the colors.
For example, if the pigment completely absorbs the red part of the light, then the rest of the light we see (basically blue and green) seems to us collectively yellow. Then, we identify the pigment as the yellow pigment.
But if you want to see something colored, you have to use pigment, it doesn't make sense. That means you have to absorb some colors of light, even if you don't. Some colors or frequencies in the light can be eliminated in other ways.
The rough surface of a metal is similar to the color separation method. When light falls on that metal if some color or frequency does not return directly and spreads from left to right, the light that returns directly to our eyes will make those colors disappear. That means we will see the rest of the colors of the rest of the light. Conquer the fort!
Think fun. Red, blue, green, a whole picture can be made without changing these colors. Just with a metal plate that has nanometer-size ups and downs. This is exactly what was done in the Dagrotype of the nineteenth century. The silver-mercury particles that fell on the plate after exposure spread the whole picture by scattering some of the light colors and removing them as needed.
Scientists set out to find out exactly what scattering light is. The idea is that if you can come up with the right theory, you will come up with a perfect technology for colorless "color printing". What was once the stage of art will now become infallible science.
The basic principle of the daguerreotype is as follows: the more light falls, the more closely the silver grains are formed, the less chance of mercury blocking. Therefore, in places where there is more light, the grain size made of the silver-mercury mixture is smaller.
In low light areas, the number of silver grains is less and more scattered, so a lot of mercury can accumulate on each grain and become a drum. The grain size is big here. In other words, when more light falls, small grains, in less light, large grains. The picture is being made by the combined efforts of all the grains on the plate, big and small.
Grains of so many sizes, some near and some far away, what is their combined effect, the scientists did not go to the moon-catching attempt to calculate that figure. Started with a relatively simple number.
While taking pictures in the scorching sun of the day, many of us noticed that the sky behind us turned white in the picture. This is called the over-exposure. Excessive light penetration has occurred. The color seen as a result of this over-exposure in Dagrotype is bluish.
Scientists have caught the extreme case of over-exposure. Suppose the whole plate is over-exposed to the sky. Then the size and arrangement of the grains are roughly the same everywhere on the plate.
The size is relatively small and it is less likely that any of the grains will become discolored. In this case, what happens if light falls on any one of the grains, the figure will be reduced.
Scientists based Maxwell's electromagnetic formula on what happens when light falls on a grain, thinking it is a hemisphere sitting on a plate.
They measured the average size of the grain separately. Given that size, there are two special wavelengths of scattered light that have more intensity: one is blue, the other is red. If you see the plate more directly than the blue light if you see the plate more horizontally than the red light.
In reality, that is what happens. The over-exposed daguerreotype looks bluish when viewed directly, but reddish when viewed from the edge. The same picture changes color when viewed from different angles.
In this way, it was shown that a single grain is capable of creating color through scattering. That figure could be matched with reality. The scientists then analyzed the grain size, what would happen if it contained more mercury than silver, the effect of the gold layer, and so on. The research paper is explored below for enthusiastic readers.
Now, by making this figure more difficult, the combined effect of many grains, in fact, what kind of optical response is taking place in Dagrotype, that "picture" has to be highlighted. But scientists have acknowledged one thing.
Without all the modern tools of nanoparticle research, pioneers like Dagger in the nineteenth century have been able to do research on what Kamal did, as if he had the moon in his hand. It would not have occurred to them to go so far in this game of color creation without color.
 To learn more about the history of photography, watch this wonderful George Eastman House video series: https://www.youtube.com/watch?v=me5ke7agyOw&list=PL4F918844C147182A. Located in Rochester, New York, the museum houses a large collection of daguerreotype.
 Nineteenth-century technology: The plasmonic properties of daguerreotypes, Schlather, Gierl, Robinson, Centeno, Manjavacas, PNAS, 2019 Jul 9;116(28):13791-13798. DOI: 10.1073/pnas.1904331116.
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© 2020 Shoaib Rahman
Shoaib Rahman (author) from London on July 12, 2020:
Thanks For Your Feedback, Shawindi!
Shawindi Silva from Sri lanka on July 10, 2020:
I learnt so many things that I've never known.