Go to my Home page.
Go to my Joy of High Tech page.
Being the occasionally interesting ramblings of a major-league technophile.
Capturing the Soul
The oldest known photograph still exists. It reproduces an engraving of a boy leading a horse. It was made in France in 1825 (or perhaps 1824) just four years - or maybe three - after Napoleon died. It was made on a glass plate coated with a special preparation of varnish.
Note that there is a silver nitrate image of a leaf, creator and provenance unknown, which may date as far back as 1790. However, that is a contact print, rather than a true photograph. The difference being that the latter involves a lens to focus light.
Joseph Nicéphore Nièpce, who had served under Napoleon during his campaigns in the South of France and Sardinia, was from a family of inventors. Among their other accomplishments, his older brother held a patent for the first recognizable internal combustion engine.
The varnish image was just one approach Nièpce used; his later techniques apparently were better suited for making images of life, as opposed to reproducing artwork. He was familiar with lithography, using specially prepared stones for printing. He knew that natural pitch combined with lavender oil could also be used to create printing plates. He knew that pitch would harden when exposed to direct sunlight. Combining those with other knowledge, he poured a layer of the mixture on a copper plate (he later used pewter) placed the plate in a small camera obscura, exposed this assembly to several hours of sunlight, and then carefully poured a mixture of lavender oil and white petroleum (this may be a particular distillation of mineral oil) over the surface of the pitch. The light-hardened portions were less affected, producing a vague, raised image only visible at certain angles. The second known photograph was thus produced by the same man who had produced the first, using a different method. He may have hoped to use this second method to make positive prints in a press, but that is pure speculation; little documentation of his work survives.
The camera obscura (Latin for dark room) was a curiosity and artist's aid. By preparing a room so that the only light entered through a pinhole at a window, an image of what was outside could be cast on the wall or a screen. More advanced versions used a simple lens. Eventually, the name passed to a box used to produce the same effect, generally so an artist could trace the image cast on a piece of paper. Nièpce knew others had tried to capture the image of the camera obscura chemically without success. With his new lithography process, he knew he could do better.
Earlier attempts had largely centered on such compounds as silver nitrate, which darken with exposure to light. However, the result was fugitive, quickly turning solid black even from the light needed to view it. The bitumen process of Nièpce didn't have that problem. It was so insensitive to light that the image could be viewed in a leisurely fashion, besides possibly being used to make prints. In fact, modern efforts to reproduce the effect require up to five days of exposure in direct sunlight. There is considerable evidence he also created ways to fix the image, making it lightfast.
The copy of the engraving mentioned above was apparently made in full sunlight, using one of the box camera obscura units. Unfortunately, none of the details of how it was prepared, produced or fixed survive.
The second oldest photograph shows part of the inside of an upper window and the outside roof of a farmhouse, and some of the landscape beyond. For several decades this was thought to be the first photograph, but the one of the boy and horse mentioned above is now considered by a consensus to hold that title.
Louis Jacques Mandé Daguerre worked with Nièpce for some years, but after the latter's abrupt death in 1833, Daguerre - while acknowledging the contribution of Nièpce's own work - essentially pretended that the earlier technique never existed. There are many possible reasons for this, and most likely a combination of these was responsible.
The daguerreotype returns to silver compounds for chemical function, but is far more successful than earlier uses of this material. Silver is exposed to iodine vapors to create silver iodide crystals (later bromine is used). After exposure, mercury vapors are used to develop the latent image. This is then fixed by soaking in sodium thiosulfate. Normally, the silver is in the form of plating on a copper sheet. The resulting image is very fragile, physically, and can literally be rubbed off the silver by careless handling. It is also only visible at a narrow angle of viewing. Finally, it cannot be used to make prints, being opaque. With difficulty, it can be reproduced by being photographed. However, if protected physically (daguerreotypes usually came in glass-fronted cases) the image is stable and lasts indefinitely.
Despite the limitations, daguerreotypes were a revolution. As the first practical method of automatically recording images the process allowed the permanent and objective recording of visual information. They froze a moment in time, preserved indefinitely. While the scientific establishment needed a while to understand the full implications of this, examples of usage for scientific purposes were soon evident. The first known successful astronomical photograph was a daguerreotype. In 1840, John William Draper - a doctor and chemist interested in the effect of light on certain compounds - used a three inch lens (presumably double-convex) to produce a one inch image of the full Moon in a twenty-minute exposure.
The result is a beautiful image of the Moon in silver and shadow. This is remarkable, considering that the word "photograph" had only been invented the year before, by German astronomer Johann Heinrich von Mädler, and popularized by British astronomer John Frederick William Herschel. This accomplishment was quickly followed by images of the Sun and a few bright stars.
This was all well and good, but even the best daguerreotype is monochrome. How to make color images?
In 1850 the Reverend Levi Hill claimed to have invented the first color photographic process. He called his creation heliochromy, though today it is more commonly known as Hillotyping. The details are vague, since Hill was worried about his work being stolen and left few written records. Surviving examples of his photographs show a mixture of actual photographic color and hand tinting. Examination of his surviving photos reveals that Hill built up layers of metals which reacted to different colors to produce an iridescent effect, but he wasn't able to get the full spectrum. This examination also proves that he manually added color tinting.
Note that there was already a large market for hand tinting of daguerreotypes.
The Reverend Hill caused a sensation... and an uproar. Conventional photographers were outraged at his claims, as well as the fact that people were putting off getting photographs from them because they were waiting for the color version. No less an authority figure than Samuel Morse examined Hill's photographs and stated flatly that there was something to the man's claims. In the end, Hill was never able to improve the quality enough to make a successful product. However, more than a century later an art historian managed to locate a copy of a book Hill published on his technique. (Most were burned under a court order obtained by a group of daguerreotypists.) After some effort, he managed to produce some photos with dingy but undeniable colors. Hill, who died in 1865 - likely as a result of inhaling the toxic fumes produced by the photography of the day - actually had something.
As the Nineteenth Century progressed multiple methods of photography were developed. Most of the early ones were similar to daguerreotypes, depending on an active plating of metal on a backing material. The techniques improved, but retained the largest failing of the daguerreotype: they were opaque. This changed with the process of laying a light-sensitive emulsion on a glass plate, first wet then dry. This produced a negative monochrome image which could be used to make positive prints on paper similarly treated with a photographic emulsion.
The interest in color photography did not start with - and certainly did not end with - Hill's work. There were many efforts in the last half of the Nineteenth Century to create color photographs. Some were successful, but impractical for most viewing, such as making three monochrome prints on glass plates, each through a filter in one of the three primary colors. Stacking these glass plates and shining a white light through them produced a color image. Even if the plates were perfectly aligned, due to the thickness of the glass the image was only properly viewed from a very narrow angle. (This is a repeating refrain in early photography; that an image could only be seen at a very narrow viewing angle.)
Another attempt at color photography was also technically successful - actually more true to reality than modern three-color methods - but too difficult to be practical. This worked differently than any other I have been able to find information on. During trials by Edmond Becquerel with silver chloride on a silver plate to reproduce colors, he developed a method to use the property in photography. His process created interference patterns where the light reflects from the layers of silver chloride, interfering with the light still coming in. This creates reinforcing and canceling patterns. These interference patterns - much in the same way pearl and other, similar materials create iridescence - made colors. When, after development, white light reflected from the plate, it would be scattered at the silver grains in the emulsion in all directions. The scattered light fields having the same wavelength as the period of the lamellae in the recording material would be in phase, interfere constructively, and together create a strong color image. Because of the physics of the situation, the colors were determined by the wavelengths of the impinging light. This method of color photography has some similarities to holography, and is known by some as The One, True Way. It is true color photography, reproducing the entire spectrum, rather than just combinations of the three primary colors through which humans perceive color.
Unfortunately, while Becquerel's process worked the colors faded rapidly. Gabriel Lippmann later took the idea and greatly improved it. By placing a photographic plate emulsion side down on mercury and using a forty-five degree mirror to turn the horizontal beam entering the camera into a vertical one shining down on the plate, Lippmann created a similar effect but one which did not fade. (Some descriptions state the back of the emulsion was "coated" with mercury and the plate mounted in the camera normally. Likely, Lippmann used more than one method in his experiments.) Once fully developed, placing the plate against a mirror and shining a light through it revealed the image, though only at a narrow viewing angle (yet again). Lippmann presented his first, crude color photographs in 1891.
Lippmann was a physicist working in an era of great exploration; he made several notable discoveries and created several notable inventions. However, it was his work in color photography for which Lippmann was awarded the Nobel Prize for physics in 1908. Even though the process he created was little more than a curiosity. Which demonstrates how strongly and deeply people were still fascinated by photography, decades after the Daguerreotype became successful. Though some sources state that the long exposures required for the Lippmann process meant no portraits were made with it, one of the surviving color photographs is of the by then elderly Lippmann himself.
An interesting note, here, is that Becquerel was an early experimenter with radiation, and Lippmann taught both Marie and Pierre Curie!
Arguably the first successful and practical color photography was by the aptly named brothers Auguste and Louis Lumière. They used several processes, some improvements on the work of others (they worked with Lippmann) and some all their own. Interestingly, one involved dyed potato starch grains. Due to the particular nature of their process, the result was a direct positive (that is, the colors were realistic on the original, rather than being reversed). The result was beautiful, pastel colored images. This Autochrome process was used into the Thirties, including for motion pictures, as Lumière Cinecolor. Some of their other methods achieved wider success. These were, of course, widely copied, and a plethora of -chrome this and and that methods of color photography soon appeared.
The impact of photography went far beyond putting most portraitists out of work and allowing the immediate and objective documentation of events. The miracle of having a lifelike - even if monochrome - image of yourself, a loved one, the family ranch or whatever became a huge fad. Once film - a strip of flexible, transparent material with the photographic emulsion bonded to one side - replaced glass plates, photography really took off. For a few decades - from late in the Nineteenth Century until early in the Twentieth - there was actually an egg shortage caused by photography. One of the best - and probably the safest and most economical - fixatives for both negatives and photographic prints was a protein in egg whites.
A cautionary note, here. Modern color photography - whether negative or print - is inherently more fugitive than monochrome. Black and white photographs using the silver nitrate process can survive far longer than color photos in the same environment. For this reason, until recently if the color of something wasn't important, archival images made of it were monochrome. Black and white microfilm and microfiche might wear out from use, but they're not going to go bad just sitting on a shelf any time soon.
Glass plate negatives are actually still in use, though today only for specialist purposes. (There are even Daguerreotype hobbyists and novelty photographers.) As film improved, so did the glass plates, especially in exposure times. Also, due in part to having a more rigid substrate, they have a grain so fine that modern image scanners need additional magnification to access it. (Note also that for the most common photographic chemistry there is an inverse relationship between grain size and exposure time.) This made them far more suitable for things such as astrophotography - where recording fine detail was more important than speed. (Some glass plate astrophotos involved aiming the telescope at the same point in the sky for more than one night of exposure.) I once saw a series of images made from a scan of a large format glass plate negative. The first showed the full plate, a landscape with a farmhouse small in the distance. Each successive scan increased the magnification, zooming in on a particular part of the photo. The last image was grainy, but still quite recognizable: There was a young girl standing in the door of the farmhouse. A door which wasn't even visible in the first image.
Eventually several methods of color photography were tried, with nearly all color film photography eventually being variations on the same theme: Three (sometimes four) layers of film, each of which is sensitive to one of the primary colors. Through time, both color fidelity and lightfastness of negatives and prints improved. Only to be replaced, relatively recently, by digital photography.
We have it too easy, today. You can take a photo with a digital camera, upload it to your computer, tinker a bit - adjusting the brightness, contrast, color balance and so forth, and perhaps cropping and straightening - then print it out or have it printed. However, we need to remember that it wasn't always this easy. Sometimes you need a sense of process to appreciate what you have.
This document is Copyright 2010 Rodford Edmiston Smith. Anyone wishing to repost it must have permission from the author, who can be reached at: firstname.lastname@example.org