Introduction

“Photography has indeed advanced since the ‘good old times,’” one photographer wrote in 1886.^​2​ This “advancement” was the development of orthochromatic photography, the increase in optical sensitivity of photographic plates beyond their native blue sensitivity. This development had a drastic impact on the ways photographers were able to capture the world around them and made possible the development of color photography. [Note, historically, the term sensitivity is referred to as “sensitiveness” and, in this article, will be seen in some of the direct quotes.]

Standard silver halide plates, commonly used in the “good old times,” were sensitive primarily to the blue region of the spectrum, with greatly reduced sensitivity to the greens and reds.  Yellows and reds appeared darker in the image than blues.  “The result is a very false rendering of ‘values,’” stated William Burton.^​3​ Blues should not appear lighter than yellows. There were two main challenges in the development of orthochromatic photography: decrease blue sensitivity and increase green and red sensitivity. According to John Tennant, colors reproduced in orthochromatic images should appear “in their true relative values or luminosities; in other words, so that the blue, the green, the yellow, the orange, and all their various modifications, shall, in our finished prints, look just as light or as dark as they do to the eye in the originals.”^​4​

In 1873, Hermann W. Vogel was the first to publish methods for using aniline dyes to increase the optical sensitivity of collodion plates.^​5​ He claimed his 1873 photograph of a blue ribbon on a yellow ground was the first orthochromatic photograph.

The goal, of “orthochromatic” photography was the reproduction of the lightness of different colors in their correct visual proportions. One source wrote that the goal was to make plates sensitive to all colors of the spectrum and capable of reproducing them in the “true proportion of their brightness.”^​6​ Another source quoted Prof. Dr. J. M. Eder: “Orthochromatic plates are those which, by optical or chemical means, reproduce photographically all the colors in the same relation of intensity as the eye sees them.”^​7​ Orthochromatic plates served to “harmonize contrasts, whether in the dress of the sitter or a view from nature.” This phrase likely refers to colors having the correct values relative to each other.^​8​ Although it was understood that some colors could not be reproduced in their “true luminance,”^​2​ the respective values of all colors should be correct.^​9​

Orthochromatic photography was made possible by orthochromatic plates, that increased spectral sensitivities. The term “orthochromatic” was used interchangeably with the term “isochromatic”; their meanings are subtly different. The word “Isos” is Greek for “equal, while “Ortho”: is Greek for “right,” or “correct.”^​7​  “Orthochromatic” has the connotation that the colors are reproduced correctly, though not necessarily equal across the spectrum, as “isochromatic” might connote. We will use the term “orthochromatic” throughout the rest of this article for consistency.

Understanding the relationship between how colors appeared and how they were rendered in black and white was key to the development of orthochromatic technology. The focus was not so much on reproducing the absolute lightness of colors, but on their relative tonal values.^​4​ The terms “value” and “tone-rendering” were used similarly in this context. It was important that photographers understood how the appearance of the final negative plate was affected by exposure, plate characteristics, and chemical processes.

Photographers also benefited from understanding how the human visual system processed tonal values differently than the photographic process. William de Wiveleslie Abney noted how the peculiarities of color appearance influenced perception of value. He understood that color appearance was dependent on illumination and visual adaptation.^​10​

In one example, Abney wrote how the relationship between reds and greens might vary depending on the illumination. “Supposing we proportionally reduce the light falling on each [red and green] we shall see that the brightnesses no longer hold.”^​10​ If red and green are of equal brightness under one illumination, the values may not appear equal if the intensity of illumination is reduced. He continued, “To judge, then, of the luminosity of the colours we must know the intensity of the light which calls them into being. Thus, a picture in which there was red and green might, under bright illumination, show a particular red, as brighter than a particular green, whereas, in a sombre light, the reverse might be the case. It is well known that toward the evening, the last colours which appear vivid to the eye in pictures in a picture gallery are the blues, the reds disappearing early.”

Painters of the day understood how the relationship between the values of different hues in their paintings might appear different in the outdoor lighting in which they were painted than in the interior lighting in which they were displayed. The painter might try to simulate the lower illumination of interior lighting by closing their eyes partially when painting outside.^​10​

Photographers’ challenges differed from those of painters since the final print would not have any color. However, photography had the advantage of being completed in stages. The taking of the image was only the first step in the artistic process. Careful selection of plate, developer, and processing time could let the photographer fine-tune the tone reproduction (relationship between tones in the image) in the darkroom. For this, careful selection of plates was key. “The best plate…will be the one giving the greatest number of distinct gradations between these limits.”^​11​ The limits were maximum transparency (the fog) and the maximum density of the plate. It was around the late 1800s, the same time as the development of orthochromatic technology, that Hurter and Driffield, among others, began exploring the science of tone reproduction. But for most photographers, good sense and logical thinking were enough to ensure success.

Making Orthochromatic Plates

If we think about a negative, areas that receive the most light are black and areas that receive the least light are transparent, with varying gray levels between. The amount of blackness is referred to as the density. For a black and white negative, the same exposure time will give different densities for different regions of the spectrum. Standard plates were most sensitive to blue, so very short exposure times were needed to build density for blue objects. A longer exposure time was needed to build density for green objects, and an even longer exposure time was needed for red objects. In reality, subjects contain many different colors. Imagine a scenario in which you are photographing a scene with blue, green, and red vases, and each vase reflects roughly the same amount of light. When photographed, the blue vase would be dark and the green and red vases would be light on the negative. When printed, the blue vase would appear light and the green and red vases dark. Visually, though, the green vase appears brighter than the blue and red vase. Shouldn’t the print show the same relationship between light and dark as we perceive the scene to have?

Until the 1870s (the “good old days”), it was generally accepted that blues would appear lighter than greens and reds. This was a fact and not really a problem. As the photographer, Maximillian Toch, stated, “All things measured by comparison, and a good photograph, be it taken on any plate, if exhibited alone cannot be criticized for chromatic value.”^​12​ A photograph is judged on its individual aesthetic merits. The difference between color values in a scene is more pronounced with purer hues, such as flowers and art pigments. However, in nature, all colors “have a large quantity of white light mixed with them, and the falseness of rendering is much less than might be expected.” If we think about nature and the cities and fashions of the 1800s, much of the palette is some form of gray, brown, or other muted color. White and black muted the colors of the natural world and reduced the impact of the “false color” apparent in standard negatives.^​3​

But not everyone was satisfied with the status quo. The use of aniline dyes was increasing in fashion and interior decorations, and photographs provided the public a means to show off their wealth. Intricate designs woven into fabrics and painted onto interior pieces could not be properly rendered using standard plates, nor could oil paintings be shown with the proper tonality. The only solution was to improve plate technology and increase sensitivity to the broader extent of the spectrum.

Wet and dry silver halide plates were made sensitive to greens and reds by exposing them to a solution containing certain dyes. Vogel first succeeded in creating orthochromatic plates using a red dye called coralline. Col. J. Waterhouse and Vogel both took credit for the first use of another red dye, eosine, in 1875.^​13​ Regardless of the originator, eosine only became practical as a sensitizer after another pair of scientists, Clayton and Attout Taillefer, published a method for “sensitizing dry plates with an ammoniacal solution of eosin.” Eosine was also recognized as a sensitizer by Louis Ducos Du Hauron and Charles Cros.

Frederick Ives was also active in the development of orthochromatic plates in the mid-1870s. Ives championed the use of chlorophyl as a sensitizer, first proposed by Becquerel in 1875.^​5​ Ives focused on chlorophyl due to its ability to increase sensitivity to red more than other available sensitizers.^​6​ However, not all chlorophyl solutions were created equal. Ives found that chlorophyl from Blue Myrtle leaves was more effective and longer-lasting than chlorophyl from other plants. It increased plate sensitivity to red, orange, yellow, and green.

Ives also experimented with synthetic dyes. He photographed a color chart containing wool cloth dyed in red, scarlet, yellow, green, blue, violet, and magenta to demonstrate orthochromatic photography with plates sensitized using different dyes.^​14​

He tested ordinary plates, plates sensitized using eosine exposed through a yellow screen (see the next Section), plates sensitized using chlorophyl, and plates sensitized using chlorophyl exposed through a scarlet screen. This experiment was not unbiased. Plates sensitized with eosine were known to have less sensitivity in the reds than chlorophyl, and Ives intended to show this conclusively in his experiments.^​6​

Orange and yellow screens, glass filters as we would refer to them today, were used to dampen the amount of blue light and help even out the exposure across the spectrum. However, since so much of the action of the plate was from blue light, the use of a screen greatly increased exposure time. Ives increased sensitivity to greens, yellows, and oranges by treating the plates with a “tea organifier”, thereby reducing exposure time.^​14​

Ives published his chlorophyl results in 1879, but, like Vogel, his process did not excite the public.^​6​ One known disadvantage to organic sensitizing dyes (such as chlorophyl) was their tendency to break down. Ives claimed to overcome this issue by heating Blue-Myrtle leaves in alcohol with zinc power to prevent spoilage. Another issue was the sensitivity of chlorophyl to dark reds.^​14​ A substantial portion o the photographic process was completed in the darkroom where development times were often judged visually under a red safelight. Although Ives claimed the red sensitivity as an advantage, chlorophyl plates could become fogged if developed under a red safelight.^​6​  Chlorophyl required a different type of safelight than the standard deep red, was not readily available, and could not be applied to the gelatin plate process. Ives discovered a method for sensitizing gelatine-bomide dry plates with chlorophyl, starting with the fastest commercially available plate, then “flowing [the plate] with the alcoholic solution of chlorophyl, then drying rapidly, then soaking in water for at least five minutes, after which they may be used at once.”^​15​

Vogel and Ives vehemently argued over who created the first orthochromatic plate. Ives claimed Vogel’s first image of the blue ribbon was not a practical demo: “The plate [of the ribbon] showed no increased sensitiveness to the red, and the experiment, though of considerable scientific interest, did not indicate a practically useful process.”^​6​ He continued, “I obtained, with these chlorophyl plates, the first photograph in which all colours were reproduced in the true proportions their brightness.” Ives later used his chlorophyl-sensitized plates to create what was arguably the first three-color photographic reproduction of a painting in 1883 (red, yellow, and blue).

In 1884 Vogel developed azaline, a new sensitizing cocktail that gained much positive support. Ives argues his sensitizer was first and better: “Dr. Vogel’s new process was not only no better in any respect, but the plates were insensitive to scarlet and ruby-red, and therefore would not photograph all colours in the true proportion of their brightness.”^​6​

Not all aniline dyes could be used as sensitizers for silver bromide.^​7​Sensitizing plates was not like dying cloth. The visual color of the dye did not always correlate exactly with the spectral sensitivity of the plate. Rather, a chemical reaction had to occur between the dye and the silver halide. Vogel stated that sensitizing dyes must bond to the silver bromide for there to be any increase in sensitivity (the presence of a dye itself is not enough to increase sensitivity).^​6​ Ives’ chlorophyl, for example, absorbed red but increased sensitivity to yellow and green due to a chemical reaction with silver bromide. Abney believed “that the new sensitiveness [from adding dyes] is due to a decomposition, by light, of the dye itself, and that the intimate mixture of this product with the sensitive salt gives a nucleus on which silver will deposit in exactly the same way that it will deposit on a glass plate on portions which have not been properly cleansed. Dyes which are most effective are those which are most fugitive.”^​10​

The quantity of dye used was also important. Optical sensitizing (increase in overall sensitivity) occurred when a large amount of dye was used.^​16​ Chemical sensitizing (bond with the silver bromide and change in spectral sensitivity) occurred when a small amount of dye was used. Scolik cited an amount of sensitizer in a solution of around 1:20,000.^​17​

Beginning with Vogel and Ives, scientists experimented with many different dyes, each resulting in plates with different spectral sensitivities. In 1886, Scolik listed several common sensitizing dyes: “Eosine yellow and eosine blue shade, iodine cyanin, erythrosine, methyl violet, aniline violet, iodine green, azelein, Hoffman’s violet, acid green, methyl green, rose Bengal, pyrosine, chlorophyl, saffrosine, coralline, saffranine”^​17​ Among all the sensitizers, Ives felt his chlorophyl process was the best because it was the most spectrally even.^​15​ Edward Boissonnas listed sensitizers that could successfully increase sensitivity to different regions of the spectrum.^​7​ Aniline greens (acid green and iodine green) and chlorophyl improved red sensitivity. Cyanine, Vogel’s azaline (cyanine and chinoline red) increase sensitivity to red and orange. Hoffman’s violet increased sensitivity to orange, yellow, and green, and dyes from the eosine group increased sensitivity to greens and yellows. A warmer eosine increases sensitivity to green, yellow-green, and yellow (bluish eosines have an absorption band further in yellow).^​17​

Charles Scolik noted that, for eosine to work as a sensitizer, some silver nitrate was required in the emulsion to aid bonding of the eosine to the silver. ^​17​ Of the different cyanin sensitizers, cyanin iodide worked best. Cyanin helped improve orange and red sensitivity in larger quantities. Some dyes could be used in combination for an overall improvement, while the action of dyes in combination had an inhibitory effect. It is also difficult to determine the exact proportions in which dyes should be mixed together.^​7​ Vogel’s azaline, a mixture of cyanine and chinoline red, was an example of a productive dye mixture. Abney found that cyanine and erythrosine could sensitize a gelatine-bromide plate when applied to the surface. However, Abney preferred sensitizers from the eosine group because “it seemed to us more important to provide a clear working ortho-chromatic plate of pronounced yellow and orange, and perhaps fainter red sensitiveness, than one of which would need more painstaking work, and would only show strong orange and red sensitiveness, such, for instance, as cyanin produces; pure red sensitiveness is but seldom required.”^​18,19​

Selection of the most appropriate sensitizing dye was only half the battle. A plate could not be made orthochromatic without an appropriate sensitizing process. Ives, working with gelatino-bromide plates ten years after his initial chlorophyl experiments, sensitized them by flowing the plate with an alcohol solution containing the sensitizing dye, drying the plate, then soaking in water.^​6​ He found that erythrosine and cyanine produced even greater sensitivity than chlorophyl (yellow and green only for erythrosine and into the orange and red for cyanin).^​15​ However, some experimenting was required to determine the best plates for the process as different emulsions might be used.

There were two general methods for sensitizing dry plates: 1) adding the sensitizing agent to the emulsion before coating the plate, or 2) soaking the prepared plated in sensitizing solution.^​18​Boissonnas preferred adding the sensitizing dye to the emulsion before coating the plate. He noted several disadvantages to the soaking method:

1. “Spots or lines arising from a deposit of the dye on the surface of the plate.
2. Partial or total fogs.
3. Development with oxalate only gives weak and fogged negatives. Pyro, on the contrary, gives strong and pure negatives.
4. The general sensitiveness is diminished by a great number of substances (this being not always the case with the other process).
5. Negatives obtained on these plates are generally highly colored in red, yellow, etc. according to the dye used, which may be prejudicial for copying the positives.
6. The most serious of these defects is that plates so prepared deteriorate in a very short time, even in a few days, according to the dyes employed; the edges blacken, and the fog extends forwards the center of the plate; the negatives obtained from them having the appearance of plates deteriorated by damp, the photographs being dull and misty. Then the fog extends rapidly toward the center of the plate, as I have observed in a previous study.”^​7​

Adding the sensitizing dye directly to the emulsion helped prevent staining and spots, minimized fog, broadened its use with different developers, and increased white light sensitivity and plate longevity.

Contrary to Boissonnas, Scolik recommended bathing standard plates in a sensitizing solution containing a combination of 9:1 eosine yellow and cyanin. The results were not repeatable, and it would have been preferrable to include the sensitizer in the emulsion before application to the plate.^​17​ G. L. Addenbrooke also wrote of soaking ordinary silver bromide plates in a solution containing the sensitizing dye. The resulting plates were similar in color sensitivity to commercially available orthochromatic plates, and more sensitive overall (relative to the speed of the “mother emulsion”).^​18,19​ He also noted positive results when adding sensitizer in an ammonia bath, while Acworth noted plates lasted longer without the use of ammonia.^​16​

George Hindlesham noted many ways in which mistakes could be made in the production of orthochromatic plates. “Free nitrate of silver in {developer] composition, and an excess of ammonia will sometimes result in a slight reduction of metallic silver all over the plate. With such as these, it is convenient to use metabisulphite of potassium in the developer, and often a slight increase in potassium bromide.”^​20​ Ammonia had to be added gradually to the developer as needed. It was also important to avoid underexposing negatives. Negative density on overexposed plates could be held back during development.  Development times had to be adjusted for orthochromatic plates since color-sensitive plates built density faster.^​8​ Developers could also impact how long it took for certain spectral components to appear.^​11​

Screens

The immense action of blue light was a major problem for all glass plate negatives. Blue light caused an excessive amount of density to form on standard plates, while green and red light caused little density to form. Thus, plate exposure was driven almost entirely by the amount of blue light in the scene. (This included muted colors and neutrals of which blue light was a major component.) 

The only method for reducing the amount of blue light reaching the plate was to either modify the illuminating source, or to filter the light at the camera before it reached the negative, using a yellow or orange screen. The use of yellow screens dates back as far as 1858, when William Crookes discovered that a yellow filter placed in front of the camera lens gave a better rendering of color values in reproductions of paintings on gelatino-bromide plates.^​7​ Screens became a necessary component of the orthochromatic process. Reducing blue light reaching the plate helped emphasize the effect of the sensitizing dyes. While there was no increase in the green or red light, increased sensitivity of orthochromatic plates to those colors, coupled with the reduction in blue light, created a more uniform spectral sensitivity.  

For studio portraiture, the solution was simple. Gaslight and electric illumination emitted a small amount of blue light and satisfied the needs for orthochromatic plates.^​3,7​ Yellow or orange “screens” as they were referred, were necessary for all other applications. 

The use of yellow screens was contentiously debated among practitioners of orthochromatic photography. Ives argued in 1895 that ordinary plates could be made orthochromatic by the selection of an appropriate screen alone, claiming that the screen only served to increase exposure time but did nothing for the “color rendering.”^​21​ Some plate makers, such as Cramer in the U.S., claimed to make orthochromatic plates that required no yellow screen. William Burton saw those claims as pure marketing.^​3​ Ives did note that others disagreed with the notion that an ordinary plate could be used with a color screen alone. Tennant was among the users who felt a yellow screen alone was not sufficient, that most practical users inevitably employed the screen to achieve their desired results.^​4​ The real problem was that, except for a select few scientists (such as Ives), general practitioners did not fully understand the effect of screens on the action of plates.^​21​

While yellow and orange screens undoubtedly helped achieve a more uniform spectral sensitivity, their use also led to much longer exposure times. The screens reduced the light necessary for photochemical reactions. Removing the blue and violet meant more of the remaining light was required to expose the plate, and thus requiring longer exposures.^​9​ Some felt that any benefit of orthochromatic plates were offset by the exposure problem.  Addenbrooke noted an increase in exposure time of at 100-200 times with a yellow screen in 1886.^​18​ That same year another author wrote of an increase in exposure of 150 times with an orange glass (from 2 sec to 5 min).^​22​ Addenbrooke went so far as to say that orthochromatic plates were only useful for copying art: “With the plates which have been generally used up to the present, this method of procedure has necessitated such enormously long exposures, that the process has been of no practical use, except for copying pictures.”^​18,19​ According to G. Cramer, portraiture and landscape photography, and similar situations with dynamic subjects, required much shorter exposure times—to avoid motion blur—than could be achieved with orthochromatic plates.^​9​ However, there were some chemical means to improving plate sensitivity.^​18,19​ For example, Acworth pointed out that exposure with a yellow screen could be shortened if the plate were treated with erythrosine.^​16​

Determining the correct exposure with a particular plate and screen was still a matter of trial and error. There were no standards governing plate speed, especially as photographers often mixed their emulsion and coated their plates manually. Even commercial plates varied considerably. One photographer, J.F.M.C., ran experiments to find the right exposure. He first exposed an orthochromatic plate without an orange filter, then determined an exposure of 3 hours was needed to achieve the same plate density as the plate without the filter.  

Just as there was no standard orthochromatic plate, there was no standard screen.^​8​ It was uncommon for practitioners to make their own screens.^​3​ Several types of screens were used by early practitioners. Ives used yellow “wet cell screens,” thin glass containers filled with a solution of bichromate of potash. Wet cell screens had the advantage that they could be fine-tuned, though they lacked portability and could only be placed in front of the lens. On the other hand, glass plate screens—thin glass plates coated with a dyed gelatin or collodion—had to be manufactured precisely, with even thickness so as not to cause optical distortions when placed before plate.^​3,9​ Boissonnas preferred to place the screen before the front of the lens in the collar of the objective to reduce the effect of the screen on image sharpness. Burton, however, noted the opposite, that screens placed in front of the negative were cheaper than screens placed in the lens due to a lesser optical purity requirement.^​3​

Screens could be placed in different parts of the camera. In addition to placement in front of the lens in the collar of the objective, Boissonnas also noted placement at the camera diaphragm, at the posterior of the lens objective, and as a yellow collodion coating on the back of the photographic plates.^​7​ Tennant noted that there was some early debate about whether it was better to use a yellow screen or dye the plate itself, an effect like collodionizing the rear of the plate.^​4​ Addenbrooke was in a quandary over the matter. All screens, he felt, had a negative effect on image sharpness, but the only suitable alternative, illuminating the subject with monochromatic light, was impractical.^​18,19​ Perhaps there was no correct screen location, as the filtering of light would occur regardless, but the acknowledging the improvised nature of this work is important to understanding the important photographic innovations that were occurring at this time.   

The general purpose and color of screens was commonly understood. The screen should cut out all dark violet and UV energy since the action of those spectral regions on plates was great. Not cutting out these rays was a common cause of failure.^​21​ However, beyond that point, screen color ranged from strong yellow, to medium and dark orange.^​8​ Photographers needed to be aware of the plate spectral sensitivity. An orange filter, which transmits less green light than yellow, would not be appropriate for a plate designed to have increased green sensitivity.  

Ives wrote that “compound color screens” might give results as good as orthochromatic plates used with a basic yellow screen. “A combination screen of brilliant yellow and fuchsine can be made that will secure on a commercial ‘isochromatic’ plate a photograph which pretty accurately represents the luminosity of the spectrum and always gives nearly photometrically correct translation of color into monochrome when used with such plates.”^​21​

Ives’ statement about accurately representing the luminosity of the spectrum echoes the goals of orthochromatic photography discussed earlier. Orthochromatic plates should produce images in which the relative values of colors in the image represent how we perceive the values of those colors in real life, or, at least how the photographer perceived them. J.F.M.C photographed a “portrait of an old gentleman, with white hair and whiskers, fairly light flesh tints, dressed in black velvet, and painted against a reddish brown background.” He observed his best results came with an orange filter, without which, “The face came out very rough, showing every touch of light absorbing colour, or, in other words, analysing the colouring, while the background, many degrees lighter in the picture than the coat, came out equally dark.”^​22​ With orange filter, “the face appeared soft, and correct in its light and shade, the slight changes of colour which go to make the harmonious painting of a face being reproduced exactly in print, thus making it an exact representation, in black and white, of the portrait on the canvas.” John Carbutt noted that paintings with different color palettes might require different screens.^​8​

Another writer noted, “when photographing strongly contrasting colors of natural objects…isochromatic plates should be used without the intervention of a screen in order to obtain the truest effects, as a screen produces an exaggeration; while for oil paintings, especially old and faded ones, a screen is desirable.”^​2​

Using Orthochromatic Plates

It is difficult for us today to imagine the precise effect of orthochromatic plates and “ordinary” plates on the reproduction of common scenes. Photographers of the late 1800s were keenly aware of how subjects would appear in black and white using standard plates. However, there was little agreement between photographers over what constituted a quality photograph. The introduction of orthochromatic plates did not simplify matters. The expansion of color sensitivity beyond the blue greatly affected the appearance of black and white reproductions and upset the aesthetic norm. Scientists, such as Vogel and Ives, could lecture breathlessly on the technical benefits of orthochromatic plates, while photographers generally felt orthochromatic plates were only appropriate for certain subjects.  

Nature photography was one discipline for which there was much debate over the use of orthochromatic plates. Addenbrooke felt orthochromatic photography applied more to art photography, less so for nature. “In photographs from nature,” he wrote, “the accuracy of outline, the beauty of the perspective, and the perfection of detail, are as a rule sufficient to distract attention from the more delicate question of the balance of shades…this defect is more or less present in all photographs detracting from them in varying degrees as truthful representations of nature and lessening their value and the pleasure they can give us…”^​18,19​ The composition of the scene was more important than the tonal reproduction of colors. According to Burton, in scenes where there is a lot of color, such as foliage, the colors were less pure than the pigments in art, and the differences between orthochromatic and standard plate reproduction were less pronounced. The differences in value between leaves is due more to their differences in lightness than to specific hue differences.^​3​ The image below shows an example of a landscape scene photographed with an ordinary plate and with an orthochromatic plate by Sanger Shepherd. While the photograph on the standard plate looks darker, it’s arguable which images is more aesthetically pleasing or correct in its rendering.

The question of “correctness” also pertained to the representation of distance in landscape photographs. Many photographers felt that the reproduction of haze added to the sense of depth in a scene.^​8​ Orthochromatic plates with yellow screens reduced the appearance of haze in photographs. Acworth described a photograph of a cityscape. A church spire was visible at 15 miles with an orthochromatic plate, but not with a regular plate due to haze. “Whether it was correct that the plate should render it, [Abney] would leave for the artist to decide.”^​16​

George Hindlesham wrote that orthochromatic plates do help to differentiate clouds from the blue sky. “By the use of an orthochromatic plate, exposed behind a suitable color filter, it is very often possible to obtain natural clouds in landscapes if a little care is taken in judicious development.”^​20​ However, one disadvantage was in the rendering of haze, “when the distance is desired to show but very faintly, in order to give atmosphere to the photograph. As this is generally of more or less bluish tint, the screen used for the foreground will sometimes bring the distance a little more forward than it should.” Sanger Shepherd also felt that distance should be rendered as the eye sees it. “The reflected white light is one of the great charms of landscape, for without it we have no impression of distance or atmosphere, so that for this purpose at least I do not think we should try for complete correction.”^​11​ Interestingly, haze in landscapes could also be reduced using a polarizing filter, a common technique in modern photography. Polarization was available in 1898, but its use would have been questioned by photographers who wanted to retain haze in their photographs. As a compromise, a light yellow screen, not completely opaque to blue light, could help with the use of orthochromatic plates while retaining some of the haze.^​11​ 

Unlike Hindlesham and Shepherd, Acworth felt that ordinary plates, not orthochromatic, exaggerated the haze in landscape photography, making the image appear foggier.^​16​ Cramer also argued that the reduction of haze by orthochromatic plates gave separation between white clouds and blue sky. Clouds and sky tend to blend together due to the blue sky giving the greatest exposure on regular plates. The same was true for seascapes, where separation between the water and sky was essential. Burton felt hazy distances were better rendered using orthochromatic plates, which gave better differentiation between clouds and sky, and snow-covered peaks and the sky.^​3​ Sunsets and autumn landscapes also benefit from orthochromatic plates sensitive to orange and red.^​9​ 

One might also argue that the quality of a landscape photograph, using either standard orthochromatic plates, was really a matter of process. Maximilian Toch wrote about the reproduction of clouds: “I might state that from my experience clouds can be photographed on ordinary plates very satisfactorily, practically as well as on orthochromatic plates, and it is simply a question of development to bring them out.”^​12​ The selection of an appropriate screen was also key, as Carbutt wrote: “For ordinary landscape work a very bright yellow screen is all that is necessary. A dark-yellow, or one of orange shade, would falsify distance.” ^​8​ A bright yellow screen would transmit more light overall than a darker orange, thus shortening the relative exposure. Darker screens would require 4-6x the exposure. 

Still lives of natural objects and commercial products were also common subjects for orthochromatic photography.^​9​ One example was a vase of flowers. “The vase itself was porcelain, of a bright yellow color, partaking of an orange tinge. The flowers, which were not artificial, but natural and fresh, consisted of yellow daffodils, blue hyacinths, violets, and lilies of the valley. An ordinary plate exposed for one minute gave a negative which yielded a print…in which the yellow daffodils are rendered nearly black, whilst the dark blue hyacinths appear lighter, the violets being light against the vase, which is dark, and shows strong contrasting reflections of light from the windows.”^​2​ A similar example is shown in the image below from T. Thorne Baker. The left image was exposed on a standard plate and the right image was exposed on an orthochromatic plate with a yellow screen. The blue patterning on the vase disappears with the standard plate because the plate is most sensitive to blue. The yellow leaves appear darker than the green leaves. The colors appear in the proper proportions on the orthochromatic plate.

Another vase, this one light blue with a blue pattern on a yellow background, is shown below. The blue pattern is more clearly defined with the orthochromatic plate.

Among nature’s many subjects, photography of flowers may have benefited the most from orthochromatic technology. The color of flowers is purer than foliage and flowers are perhaps more recognizable by their colors than their shapes.^​3​  An image of a field of poppies should show a clear difference between the orange petals and black seeds. The petals of blue bonnets should not be rendered lighter than the green stems. The use of orthochromatic plates with yellow screens ensured these subjects were reproduced with the proper tonality and were agreeable to the viewers own memory and experience. An image of a vase with flowers was described in another example from 1890. An orthochromatic plate was “exposed with a pale yellow screen inserted between the lenses, the exposure being three minutes. In the print from the resulting negative, the yellows are brought too near the whites in value, the hyacinth and violets still remain dark, but the daffodils and vase are lighter than their true color values, while the reflections from the vase have almost entirely disappeared, being only faintly discernable.”^​2​ Without the yellow screen (but still with orthochromatic plates), a print was achieved “in which the yellow daffodils are very much lighter than the blue hyacinth, but not quite so white as the lilies of the valley; the violets are here dark, and the yellow vase is quite of a light color, although not white; the reflections from the glazed surface of the porcelain are almost suppressed, and, contrasted with their strength in the former one, scarcely noticeable.”^​2​ 

Commercial photography and studio portraiture also benefited from the development of orthochromatic plates. In the studio, they enabled photographers to make portraits by gaslight with shorter exposures and only a modest increase in illumination. Gas light acted as the yellow filter due to its minimal blue energy,^​26​ and thus no additional light-absorbing filter was needed. However, despite the gains in sensitivity, the practical gains in color rendering for portraiture were minimal. 

The exception was fashion. Fashion drove the use of orthochromatic plates in the studio. Fabrics were dyed using saturated aniline dyes. Ladies in fine dresses expected a certain level of color contrast so patterns and designs could be properly rendered.^​18,19​ Skin tones and unique features of each subject were also rendered differently on orthochromatic plates than on standard plates. One anonymous author wrote about the reproduction of freckles in one subject: “Those incipient freckles which are scarcely visible to the eye, but, which in the case of an ordinary plate, show strongly as transparent spots, giving much trouble, or at any extra work, to the retoucher, do not show at all, or scarcely show at all, in negatives taken on orthochromatic plates.”^​26​

The reproduction of art was one area in which everyone agreed that orthochromatic plates were necessary. Unlike nature, and fashion to some extent, reproductions of two-dimensional works of art could be held side-by-side with the originals and judged on the faithfulness of the rendering.  Burton wrote that orthochromatic plates were “best” for reproducing works of art since they depend on an individual’s perception of color. Accurate reproduction of color value relationships is key to their reproduction.^​3​

Not unlike the debates around digital reproductions, some thought reproductions of oil paintings made with orthochromatic plates looked like they were overly retouched. One photographer, when viewing a subject reproduced with ordinary plates next to the same subject reproduced with orthochromatic plates asserted “that in the case of the two copies from an old oil painting, the [orthochromatic] results shown were obtained unfairly by means of alteration in the system of lighting.”^​2​

Public Perception 

The general public was initially skeptical about the benefits of orthochromatic plates.^​2​ Vogel’s orthochromatic process initially received a cool reception in 1873^​5​ but it gradually gained greater acceptance as more optical sensitizers were discovered in the years between 1873 and 1885.  Commercialization of orthochromatic plates began in 1886 by Messrs. B.J. Edwards & Co., though a patent was granted to Tailfer & Clayton in 1883 (they did not put plates on the market).^​20​ Use in America increased after 1891 (cause not given),^​8​ but by 1898, orthochromatic work was still not mainstream.^​20​

Orthochromatic plates had a bad reputation for high cost and difficulty of use. Carbutt was a manufacturer of orthochromatic plates since 1885, followed by a steady growth in the use of their plates (according to the author).^​8​ He felt that American photographers were especially hesitant to adopt orthochromatic technology, compared to their European counterparts, perhaps due to belief that yellow screens were required for all subjects. While yellow screens were generally standard practice among photographers, it is not difficult to imagine that some photographers would be hesitant to add one more variable to an already complicated process. Carbutt was one of many plate manufacturers who claimed they had plates that did not require yellow screens, a claim largely viewed as nonsense by more knowledgeable practitioners. Misinformation likely led to market confusion and supported a wary public’s skepticism.  

Use of safelights was another point of contention. In modern film development, whether black and white or color, the process takes place entirely in the dark, with standardized temperatures and processing times. Visual judgement played a much larger role in the late 1800s. The safelight gave photographers flexibility to improvise and make corrections to the processing times on the fly . “It is…very important that there should be sufficient light to clearly see the image as it appears as it is often necessary to modify the result by additions, etc., to the developer,” Hindlesham wrote.^​20​

A ruby red safelight was commonly used in darkrooms when developing standard plates. Some orthochromatic plates, however, were sensitive to the deep red safelights and would become fogged if developed in those environments. Other orthochromatic plates could be developed with a green or amber safelight, depending on the spectral sensitivity. Deciding on the proper safelight required information that was often left out of manufacturer documentation. Burton felt that there was a lot of misinformation about the color sensitivity of commercial plates from their manufacturers, if it was communicated at all. Some photographers thought orthochromatic plates should be handled in the dark. Amateurs were scared to use them. Greater communication, Burton felt, would help promote sales and lead to better practices, such as selection of the proper safelight.^​3​ However, by the turn of the century, the marketing of orthochromatic plates still had a long way to go. “The difference [between standard and orthochromatic plates] is surely not of so much value that the extra labor, expense, and trouble are justified,” Toch protested. “The average operator or amateur has troubles enough without courting more.”^​12​

An Introduction to Orthochromatic Photography, Part 2

Overcoming the difficulties of plate color sensitivity was a key development in the history of color photography. The systems for three-color photography developed by scientists and photographers such as Frederick Ives and William Kurtz depended on plates being equally sensitive to all colors of the spectrum. Otherwise, the exposure times through the red, green, and blue filters would be so different that it would be impossible to capture the subject clearly. Orthochromatic photography also sparked innovation in how scientists measure and evaluate spectral sensitivity. The spectral sensitivity of today’s films and digital sensors can be analyzed using standard color science tools and techniques. This was not the case in the late 1900s. Innovators, such as Frederick Ives, William de Wiveleslie Abney, and E. Sanger Shepherd, had to develop their own methods to measure spectral sensitivity. Only with these tools could the industry optimize plate emulsions for the market. In Part 2 of this series on orthochromatic photography, I will dive into those innovative scientific techniques for measuring spectral sensitivity and explain how they assisted in the development of three-color photography.

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Disclaimer

This article was written by Brian Gamm in his personal capacity. The views, thoughts, and opinions expressed in this article belong solely to the author, and not necessarily to the author’s employer, organization, committee or other group or individual with which the author has been, is currently, or will be affiliated.

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