© 1996 by Hisun Wong, all rights reserved

From Visualization to Print

 

Eye and Brain

Now you see it, now you don’t

Photography is a form of visual communication and a category of modern visual art, which simply means that photographs are made to be seen by a group of people other than the artist himself. Successful artists, by intent or by instinct, make use of the fundamentals of human visual perception to improve their works of art. The human reaction to an image is a complex mix of physics, emotion and experience. However, understanding the limits of human vision allows the photographer to distinguish between essential and irrelevant technical accomplishment.

Three essential components are required to make human vision possible. There must be a sufficient amount of light, a light-gathering device to receive and arrange the light into structured optical information, and a processor to sort and administer this information to make it available for further decision and action. In the human visual system, eye and brain work closely together to gather, arrange and process the light around us.

© 1936 by Dorothea Lange, Library of Congress, Prints & Photographs Division, FSA/OWI Collection, [LC-USF34-9058-C]

Electromagnetic Spectrum and Light

Modern humans are constantly exposed to a wide range of electromagnetic radiation (fig.1), but we hardly ever think about it, because our daily lives are filled with radio and television signals, radar, microwaves and the occasional x-ray exposure at the doctor’s office. Low-frequency radiation, such as in radio and television signals, carries little energy and has no effect on the human body. It cannot be seen or felt. Higher frequencies, such as infrared radiation, can be felt by the skin as warmth, and even higher frequencies, such as UV and x-rays, carry sufficient energy to be harmful to humans with prolonged exposures. The highest frequencies, such as gamma radiation and cosmic rays, are packed with energy and would put an end to life on earth, if it were not for the planet’s sensitive atmosphere and its strong magnetic field to protect us. However, most electromagnetic radiation bombards us constantly without ever being detected by any of our senses. There is only a tiny range of frequencies, with a wavelength from roughly 400-700 nm, to which our eyes are sensitive. It is the visible part of the electromagnetic spectrum, better known as ‘light’. Within this range, the human eye sees changes in wavelength as a change of hue.

fig.1       Modern humans are constantly exposed to a wide range of electromagnetic radiation, but our eyes are sensitive to only a tiny range of these frequencies. They are the visible part of the spectrum, better known as ‘light’.

The Anatomy of Human Vision

Before we get into the human visual system as a whole, it makes sense to initially understand the optical performance and visual functionality of eye and brain individually. What may come across as a small lesson in human anatomy is actually an essential introduction to the basic phenomena of human vision.

The Human Eye

The human eye is often compared to a photographic camera, because the eye, a sophisticated organ capable of focusing an image onto a light-sensitive surface, is very similar to lens, camera and film (fig.2a), but with some significant differences in operation. The eye is a light-tight hollow sphere (sclera), containing an optical system (cornea and lens), which focuses the incoming light onto a light-sensitive surface (retina) to create an upside-down and reversed image. The amount of incoming light is controlled by the iris, which adjusts the aperture (pupil) as needed. The retinal image is converted into electrical impulses by millions of light-sensitive receptors and transmitted to the brain via the optical nerve.

Sharp focusing is controlled by the ring-shaped ciliary muscle, which surrounds the lens and is able to change its curvature. The muscle contracts to bulge the lens, allowing us to focus on nearby objects, and it relaxes or expands to flatten the lens for far-distance viewing. Changing the optical power of the lens, to maintain clear focus as the viewing distance changes, is a process known as accommodation. As we get older, the lens loses its flexibility, and it becomes increasingly more difficult to focus on close objects.

At infinity focus, the average lens has a focal length of roughly 17 mm. When fully open and adapted to low light levels, the pupil has a diameter of about 8 mm, which the iris can quickly reduce to about 2 mm in order to compensate for very bright conditions and to protect the retina from irreversible damage. In photographic terms, this is equivalent to an f/stop range from f/2 to f/8, covering a subject brightness range of 4 stops or a 16:1 ratio.

The retina is lined with light-sensitive receptors of two types, called rods and cones, which are only responsive to dim and bright light, respectively. At any given time, rods and cones provide a static sensitivity range of about 6 stops. However, rods and cones are able to dynamically alter their sensitivity by regulating the amount of a light-sensitive dye they contain. This enables the retina to adapt to a light-intensity range of 1,000,000:1 and adds 20 stops of dynamic sensitivity to its static range.

Fully building up the light-sensitive dye takes about 8 minutes in cones and up to 30 minutes in rods, which is a process called dark-adaptation. This explains why our vision improves only slowly, when we move from a bright to a dimly lit room. In the reverse process, rods and cones rapidly dispose of the dye, in order to safely adapt to a brighter environment. This is referred to as light adaptation and is typically completed within 5 minutes.

All rods are of a similar design, highly specialized for low-light sensitivity. However, cones come in three different varieties, and each kind produces a slightly different type of dye, making it sensitive to a different wavelength of light. This enables color vision, very similar to the way red, green and blue color receptors enable color imaging in digital camera sensors.

In summary, rods give us sensitive night vision (scotopic) and cones add colorful day vision (photopic) to our sense of sight (fig.2b). Combining the static and dynamic sensitivity range of the retina, and adding the light-regulating support of the iris, provides the human eye with an enormous sensitivity range of 1,000,000,000:1 or almost 30 f/stops, as long as we give it the time to adapt to the dimmest and brightest lighting conditions possible.

fig.2a    anatomy of the human eye

fig.2b    spectral sensitivity of the human eye

fig.2c    population of rods and cones across the retina

fig.2d    visual acuity across retina

fig.2e    visual acuity of the human eye

fig.2       The human eye is often compared to a photographic camera, because the eye, a sophisticated organ capable of focusing an image onto a light-sensitive surface, is very similar to lens, camera and film, but with some significant differences in operation.

There are millions of rods and cones distributed across the retina, but unlike the light-sensitive particles of a silver-gelatin emulsion, rods and cones are not distributed uniformly (fig.2c). Rods predominantly populate the outer surface area of the retina, whereas cones are primarily found around the center. Furthermore, there are two small areas on the retina that are quite different from the rest, and they deserve some special attention.

Close to the center of the retina is a small indentation, called the fovea. Its center, the fovea centralis, which is also the center of human vision, is only 1 mm in diameter. The fovea contains almost exclusively cones and very few rods. In fact, nowhere else on the retina are cones so densely populated as in the fovea. Here, the distance between cones is as small as 2.5 µm, and because of this, humans have excellent visual acuity in bright light. However, peak performance is limited to a relatively small angle of view, only a few degrees, concentrated around the fovea (fig.2d). Everything outside this narrow field of view blends into our relatively fuzzy peripheral vision. Nevertheless, about 50% of the optical impulses, sent to the brain, come from the fovea, and therefore, we can assume an optical resolution of the human eye of at least 30-60 line pairs per degree. The optical resolution of the eye also depends on the diameter of the pupil or, consequently, on illumination levels. Similar to a photographic lens, overall optical performance increases with decreasing aperture until diffraction takes over. Fig.2e shows how a wide-open pupil (8 mm) is limited to 30 lp/degree, a normal pupil opening (4 mm) achieves about 60 lp/mm, and a very small pupil (2 mm) can resolve up to 90 lp/mm. For the purpose of viewing photographs, we can assume an optical resolution of the human eye of 30-90 lp/mm, which is equivalent to viewing angles of 20-60 arc minutes and covers the range from standard to critical viewing conditions.

fig.3       The optical information, collected by our eyes, travels along the optical nerve to several areas of the brain for subsequent processing.

About 20° from the center of the fovea is the optical disc. This is the location where the optical nerve is attached to the eye. The optical disc is entirely free of rods or cones, and this complete lack of light receptors is the reason why the optical disc is also referred to as the ‘blind spot’. Amazingly, the blind spot does not disturb human vision at all, because the brain makes use of surrounding optical impulses in order to fill in for the missing image information.

The Human Brain

Comparing the human eye to a camera and lens does not fully appreciate the sophisticated functionality of this complex organ, but it sufficiently illustrates the eye’s contribution to the human visual system. A similar association is often made by comparing the human brain to an electronic computer. The speed with which our brain processes visual input is about the only realistic comparison we can obtain from this analogy, because the brain is much more than just a pile of electronic circuitry.

The eye focuses an upside-down and reversed image onto the retina, where rods and cones convert the optical sensation into electrical signals, which travel along the optical nerve to several areas of the brain for subsequent processing. At first, the visual cortex, which is an area in the occipital lobe of the brain at the back of our head, differentiates between light and shadow, making out borders and edges and combining them into simple shapes. With support of the cerebral cortex in the parietal lobe, the new data is compared with previously memorized information and used to quickly recognize familiar faces and objects, while separating them from the background. But, visual processing does not stop there, because the information is now passed to the temporal lobe, where the meaning of what we have seen is interpreted, and faces and objects are given a name. In the frontal lobe, feelings are added, and finally, in the prefrontal lobe, we order our thoughts and decide what to do next, based on what we have seen.

This is a very simplified overview of the brain’s function as part of the human visual system. What actually happens in our heads is far more complex, and much of the brain’s functionality is still a mystery to modern science. All we know for sure is that whatever our brain does, it does it very, very quickly.

The Human Visual System

The human eye is a camera, and the brain is a fast computer. While this grossly oversimplified statement roughly explains the contribution of both organs to human vision, it cannot illustrate the complexity and sophistication of the human visual system. What we believe to ‘see’ is a combination of the images created by our eyes and the brain’s interpretation of them. In addition, the brain constantly supports the eye to optimize its optical performance and get the most visual information possible. Here are two examples:

The eye is able to recognize minute detail far beyond its inherent optical resolution of 1 arc minute. We can easily distinguish a thin wire against a bright sky down to 1 second of arc, but visual angles alone cannot explain why we can see the dim light of a star, thousands of light-years away. This astonishing capability is only possible with the support from the brain, because in reality, we do not look at a scene in fixed steadiness. Instead, our brain controls a constant and rapid scanning of the scene, referred to as saccadic movement, in an effort to gather more information than static observation alone would permit.

In addition, the brain keeps the eye in a constant state of vibration, oscillating it at a frequency of about 50 Hz. These subconscious micro tremors are involuntary, small angular movements of roughly 20 arc seconds, and they help to constantly refresh the retinal image produced by rods and cones. Without these micro tremors, staring at something would cause the human vision system to cease after a few seconds, because rods and cones do not record absolute brightness values but only respond to changes in luminance. The combined effort of saccadic movement and micro tremors are the reason for the amazing optical resolution of human vision and often the explanation for otherwise puzzling optical illusions.

fig.4       This is a coronal section of a human brain, revealing small optic tracts that transport visual information from the eye to the brain, and also containing portions of the large and convoluted visual cortical regions, which translate light into vision.

(image © 2006 by Michael Peres, all rights reserved)

The next example illustrates how our brain compensates for a natural deficiency of the human eye, and the large role the brain plays in determining what we see. From fig.2a, we know that there is a small area on the retina without visual receptors, called the optical disc, and a simple test will reveal its existence.

Fig.5 shows a plus sign on the left and a black dot to the right. Close or cover your left eye, and firmly stare at the plus sign with your right eye. While keeping your left eye closed, slowly move your head closer to the book. Keep staring at the plus sign, but be aware of the black dot on the right with your peripheral vision. At a distance of about 8 inches or 200 mm, the black dot suddenly disappears, at which point, its image falls on the blind spot of the retina. It may take you a few trial runs to get comfortable with this test.

Note that the brain is not willing to accept the lack of visual information caused by the blind spot. It does not disturb our normal vision, because the brain simply takes some visual information from the surrounding areas and fills in the blank spot with what, in reality, does not exist.

fig.5       This test is designed to reveal the blind spot of the human eye. Close your left eye, and stare at the plus sign with your right eye. While keeping your left eye closed, slowly move your head closer to the book. Keep staring at the plus sign, but watch the black dot on the right with your peripheral vision until it suddenly disappears when its image falls on the blind spot of the retina.

fig.6       Find yourself a willing participant and cover the playing cards with a piece of paper. Ask your test person to look at the cards, while uncovering them for less than a second. Now, ask the person what playing cards he or she remembers seeing. Most people will claim to have seen a king of hearts and an ace of spades. A more thorough look reveals that the card on the right is actually a fake, black ace of hearts.

The last two examples demonstrated how the brain makes the most of the optical information it receives from the eyes. But, as we will see in the next example, sometimes the optical information only serves as supporting reference data for the brain to make a quick judgment.

Find yourself a willing participant and cover fig.6 with a piece of paper. Ask your test person to look at fig.6 and to uncover it for less than a second. Now, ask the person what playing cards he or she remembers seeing. Most people claim to have seen a king of hearts and an ace of spades. A more thorough observation of fig.6 reveals that the card on the right is actually a fake, black ace of hearts.

Of course, the official deck of playing cards contains no black ace of hearts, and consequently, the brain refuses to take the optical information given at face value, and prefers the result of a comparison with its previous experience, instead. The brain’s conclusion is that the optical information, received from the eyes, must be wrong for whatever reason, and the card seen is more likely a common ace of spades. Nevertheless, a long enough look at fig.6 will eventually convince the brain that a black ace of hearts does indeed exist, and the test cannot be repeated with the same person, because its memory now allows for the existence of a black ace of hearts.

fig.7       Would there be a ‘man in the moon’ without the human obsession with faces and our prehistoric need to separate enemy from friend?

Human behaviorists believe that our brain is designed to make speedy decisions to protect us. When it comes to our safety, we need quick decisions. For example, the decision whether it is safe to cross a busy road or not does not rely on time-consuming calculations, considering the laws of physics. It’s done within a split second, based on experience.

Less so in modern life, but very important to prehistoric human survival, was the ability to quickly separate enemy from friend. A familiar friendly face poses less of a threat than the uncertainty of an encounter with a stranger or the frightening appearance of a known enemy, who has done us harm in the past. For this reason, a large portion of our brain is dedicated to face recognition, and it works extremely well.

It works so well, in fact, that logic and reality are often forced to take second place. Faces seem to be hiding everywhere. We can detect them in bathroom tiles, wallpaper patterns and cloud formations. Our brain is constantly on the look out for facial features. Without the human obsession with faces, there probably would not be a man in the moon.

Experienced photographers and creative artists are aware, and make use, of the importance and power of facial expressions. The lead picture, ‘Migrant Mother’ by Dorothea Lange, does not reveal the actual circumstances where, when and why it was taken, but it summarizes the unfortunate fate of an entire family through the emotions written on one face.

 

Pictorial Maturity

Combining craft and creativity

Photography is an interesting mixture of practical science, craft, imagination, design and ultimately art. This book focuses predominantly on the craft surrounding competent fine-art B&W photography. Nevertheless, the authors are well aware that it requires the combination of creativity and craft to create fine art. Fine art always depends on the combination of unique, conscious creation and the mastery of tools and materials, through which this creation is made presentable to an audience.

A visionary full of original thought, but lacking the skill to turn imagination into a presentable product, will never reach an audience. A creative photographer, without adequate control over the technical aspects of the photographic process, will always struggle to create a print that reflects the intended feeling or mood. On the other hand, a skilled craftsman without any sense for creativity may produce a beautiful product, but it is, most likely, just an ordinary duplication of an already existing item. A photographer, trained in the technical aspects of photography but lacking the essentials of creativity, will be able to consistently produce technically perfect prints, but these prints will have little or no artistic individuality. Only when craft and creativity are joined can presentable art be created, and only when presented, can it reach an audience and be given a chance to be recognized and appreciated as fine art.

In addition to the more technical chapters in this book, we have included the following two chapters to stimulate an interest in the main principles required to go from visualization to print. These chapters are by no means intended to replace a formal education in photographic art. They will, however, provide some fundamental information and basic guidelines for successful image creation and how to communicate a visual message more clearly. If you are interested in the artistic aspects of image creation beyond what is presented here, please check the bibliography at the end of this book for further reading.

From Child’s Play to Perfection

By the time we reach about two years of age, our mothers trust us enough to not necessarily hurt ourselves every time we pick up a sharp object, and they risk a first attempt of giving us a chance to test our artistic capabilities. In other words, we are presented with a piece of paper and a pencil. The results of these first inexperienced attempts always look very similar to the wild scribbles in fig.1a. These scribbles are evidence of the fact that we have absolutely no control over our tool yet. This first creative achievement and coinciding excitement is limited to drawing a few lines, some chaotic curves and many totally unidentifiable shapes. Nothing more is requested of us at this first productive moment.

Several years later, our technical skills will have improved enough to create identifiable shapes (see fig.1b). Around the age of ten, we can draw a person, tree, animal and many other familiar objects. These sketches are recognizable by other people, but they are far from being realistic images of the world around us. The skill of turning three-dimensional objects and their perspective relationships into realistic two-dimensional representations still requires much improvement of our technical abilities.

Many of the old masters spent a lifetime improving and perfecting their skills. Their ultimate goal was to create life-like images, which could easily be mistaken for the real world. Recent research reveals that even the best of them often used aids, including the camera obscura, to get the perspectives and scale relationships just right. However, this takes little away from our justified admiration for their timeless works of art. Fig.1c shows an example of this refined skill in a study by Leonardo da Vinci from around 1505, carried out in black chalk. Few people ever reach this level of perfect craftsmanship, even when devoting their entire lifetimes to learning the required skills. A modern camera can effortlessly capture an image flawlessly within a fraction of a second. Image capture does not equal creative expression. There is more to art than complete control over tools and materials.

Fig.1d shows the sketch of an unknown artist. Its uncluttered simplicity makes it sophisticated. With only a few lines, the artist created an immediately recognizable image. It does not show the technical expertise of Leonardo da Vinci’s work, but this artist was in command of the simple tools and materials he had chosen for this work. Would it be any more realistic in its details, the creative sophistication would be lost immediately. Craft and creativity were successfully joined in this image.

fig.1       Painting maturity evolves from immature scribbles (a), to drawing identifiable shapes (b), but rarely reaches the craftsmanship (c) or creativity (d) of the masters.

From Novice to Photographic Artist

Obviously, as with sketching, drawing and painting, there is also a learning curve and progressive advancement in photography. But thanks to modern equipment and automated photo-lab services, initially, moderate imaging success is easier to come by with a camera than with a pencil or a brush, which explains why it often takes a closer look to detect and appreciate different levels of photographic maturity.

The snap shooter who produced the print in fig.2a was at the beginning of his learning curve. His lack of understanding photographic fundamentals is all too apparent. Composition and focus leave much to be desired. The film was underexposed, leading to ‘empty’ shadows, and overdeveloped, resulting in ‘burned-out’ highlights. This novice had no business shooting a wedding! I’m very sorry and hope they can find it in their hearts to forgive me. This image was taken in 1975, and I stuck to my promise at the time and have not taken a wedding picture since.

The print in fig.2b illustrates a moderate level of photographic expertise. The depth of field is competently controlled, creating an in-focus image, front-to-back. Using the railroad tracks as lead-in lines, to guide the eyes across the image, makes for an effective composition. Accurate exposure and development render all image tones without losing detail, but not enough attention was given to locally optimize tonality or to give the image a clear point of interest. Overall, it is an image executed with reasonable skill, but it is not the work of a darkroom expert. The print is missing tonal depth and sparkle.

Ansel Adams once said that there is very little difference between a good print and a fine print. John Sexton worked for Ansel Adams as his photographic and technical assistant and was a technical consultant for the Ansel Adams Trust. Fig.2c is one example of his own, finely crafted prints. However, one has to see the original print to fully appreciate his darkroom skill. John Sexton spent decades refining his techniques, and he always explores every part of the negative to assemble a convincing image of maximum tonality and clarity. His secret to success is not an arsenal of expensive, high-tech darkroom equipment, but rather decades of experience, a lot of patience and a passion for excellent photographic craftsmanship.

The print in fig.2d, on the other hand, did not require exceptional darkroom skill. Similar to the sketch in fig.1d, it shows a successful image that convinces through its uncluttered simplicity. The photographer demonstrates full command of lighting and composition, and transfers it to a halftone negative, which made it easier to create a print without excessive darkroom manipulation. This image is an effective example of joining competent craft and artistic creativity in a photograph.

fig.2a-b  Photographic maturity evolves not unlike that in sketching or painting. But, with modern equipment, moderate initial imaging success is easier to come by than with a simple pencil, and it takes a closer look to detect and appreciate different levels of photographic maturity. With a little practice and some guidance, a snap shooter (a) can quickly become a competent composer (b), but it takes patience, experience and dedication to master the darkroom and become a photographic artist who consistently creates high-quality images.

fig.2c     This print is an example of skilled darkroom work. John Sexton spent decades refining his techniques, and he always explores every part of the negative to assemble a convincing image of maximum tonality and clarity. His secret to success is not an arsenal of expensive, high-tech darkroom equipment, but rather decades of experience, patience and a passion for excellent photographic craftsmanship.

Merced River and Forest, Yosemite Valley, California, © 1983 by John Sexton, all rights reserved

Are You a Hunter or a Sculptor?

Photographs can be separated into several categories, most commonly classified by the subject matter or the image purpose. The same themes often categorize the photographic artists as well. Consequently, we usually speak of fashion or landscape photographers in an attempt to convey their preferred photographic field. This may help to anticipate what photographic subjects we can expect from their body of work, but it suppresses an easily overlooked, yet fundamental, difference between many successful photographic artists. Some are hunters, and some are sculptors.

A photographic hunter prefers to go after his or her subject. Good examples of photographic hunters are landscape photographers, who travel to interesting places and visit them during the most appropriate season and at the best time of day. For them, image composition is not achieved by moving trees, rivers and mountains, but by a careful selection of viewpoint and camera angle. Landscape photographers may envision a preferred lighting situation, but they do not set it up; instead, they wait for the perfect moment. If it doesn’t work out at that very instant, they just wait or return some other time.

A photographic sculptor prefers to model subject and lighting himself. Good examples of photographic sculptors are model or fashion photographers, who prefer to work in the studio. The model is dressed and styled according to image intent, a supporting background is chosen, and the lighting is set up to create the right mood with light and shadow. The time of day or weather condition has no impact on the success of the image.

Hunter or sculptor is not a qualifying distinction of artistic value. One is not more creative than the other, but perhaps, their chosen approaches are the difference between ‘visualization’ and ‘previsualization’. Hunters and sculptors are photographic artists, who create images in different ways. The awareness of your personal preference of one approach over the other will help you along the way to become an artist yourself. Are you a hunter or are you a sculptor?

The Evolution of an Artist

The sketches and photographs in fig.1 and 2 are examples of how the evolution from crude imagery to fine art evolves in several stages of competency in handling the technical difficulties before creativity has a chance to emerge. This does not allow us to clearly conclude which came first, creativity or craft. Was it the hidden artist, unable to communicate the vision due to the lack of technical competency? Or, was there first a competent craftsman, who was no longer satisfied with technical perfection alone, and finally realized that creativity was the next necessary step? The sequence is irrelevant; only the final level of pictorial maturity is of importance. Ultimately, creative vision and exalted craftsmanship are both characteristics of the person we call ‘artist’.

Many people are first attracted to photography by the exciting technology, the lure of sophisticated equipment and the pride of its ownership. They are also intrigued by the challenge of control and enjoy mastering the equipment and materials to achieve technical excellence. Thanks for all that ingenious modern technology, designed to fit hand and eye. There is a great appeal in pressing buttons, clicking precision components into place and testing the latest materials. The results can be judged or enjoyed for their own intrinsic photographic qualities, such as superb detail and rich tones, but we need to avoid falling into the technology trap.

The hesitance to blame initial failures on one’s own way of doing things is a common pitfall. The common resistance to making test strips is an excellent example of this aversion. Rather than solving the real issues, there is a tendency to hunt after the latest and greatest inventions. Hoping that the next camera, lens, film, paper or miracle developer and another electronic gadget will fix the problem often only leads to more disappointment. It is far better to thoroughly understand already existing equipment and materials before spending significant amounts of money and endless hours to buy and test new products.

However, even photographers who have honed their skill and achieved the highest level of craftsman-ship need to consider making the final step. Tools and materials are vital, of course, and detailed knowledge about using them is absorbing and important, but don’t end up shooting photographs just to test out the machinery. Try not to become totally absorbed in the science and craft of photography, which is all too common, but put them into perspective as merely the necessary means to create your own images and eventually reach full pictorial maturity.

fig.2d    This print did not require exceptional darkroom skills. Similar to the sketch in fig.1d, it shows a successful image that convinces through competent lighting, composition and uncluttered simplicity, effectively joining craft and creativity.

 

Photographic Quality

The synergy of image, negative and print quality

Birch Trunks, New Hampshire, © 1984 by John Sexton, all rights reserved

Photographic quality has significantly matured in a variety of ways since its official invention in 1839. Nevertheless, the basic principle of using a negative and positive to create the final image has dominated analog photography since the invention of the Calotype process by William Henry Fox Talbot in 1841.

The Calotype process had the great advantage over the earlier Daguerreotypes that it allowed for multiple copies of the same image, but at the unfortunate cost of inferior print quality. The process used an intermediate paper negative, which was first waxed, to make translucent, before it was contact printed onto sensitized paper to produce the final positive image.

Glass, being almost transparent, would have been a far better material choice for a negative carrier. However, this was not a viable alternative until 1851, when Frederick Scott Archer discovered the means of coating glass sheets with a light-sensitive emulsion, which had to be exposed while still wet. His Collodion wet-plate process was not improved until 1871, when Richard Maddox discovered a way to coat glass plates with a silver emulsion, using gelatin, which resulted in the more convenient dry-plate process.

The invention of celluloid allowed for the introduction of the first flexible film in 1889, and clear polyester polymers eventually replaced celluloid in the 20th century, providing a safe and stable substrate for silver-gelatin emulsions. These and other material advances aside, the fundamentals of creating silver-based images have not changed much since 1841. Modern print quality can be far superior to the humble results at the dawn of photography, if appropriate exposure and processing techniques are applied.

Before we get into the technical details on how to achieve the highest photographic quality with modern materials, let’s define what we mean when using words such as image, negative or print quality.

Image Quality

The process of achieving photographic quality starts before the technical aspects of photography can be considered. Pointing the camera at the subject without a clear concept for the image is rarely rewarded with success, instead it reduces conscious art to accidental triumph. Image quality is the result of intentional subject selection, careful composition and appropriate lighting, all the while visualizing the final print.

Since the ancient Greeks, philosophers, artists and psychologists have been trying to understand the fundamentals of good design, defining the concepts for the ‘ideal’ and establishing guidelines to separate what works from what does not. They leave us with simple suggestions, such as ‘the rule of thirds’ or ‘the divine proportion’, and more complex visualization concepts, such as the Bauhaus ‘Gestalt Theory’. All of these are worth knowing about, and understanding these principles will enhance conscious artistic skill, but applying design concepts rigidly always conflicts with creative expression. Nevertheless, there are a few characteristics that all successful images have in common. They are the cornerstones of image quality.

1.   Create Impact
The combination of basic design principles must create sufficient impact to catch the observer’s attention and get him or her to take a closer look.

2.   Provide Interest
Once the observer starts to look, the image must provide attractive and exciting elements to keep him interested in exploring the image further.

3.   Get the Observer Involved
A quality image involves the observer and supports his image exploration through guided eye movement and intentional hindrances, inspiring the senses and confirming experiences.

Whether you are a landscape photographer, who is always on the hunt for new and interesting scenery, or a studio photographer planning out the next session and the most appropriate lighting layout, you most likely have already worked, instinctively or intentionally, with the image characteristics mentioned above. However, next time your images are on display, make a point of secretly observing the observers. Find out which of your images have sufficient impact to stop casual viewers dead in their tracks, and which images are barely noticed. Which images hold the observer’s interest for a while, and which do not retain his attention, but send him quickly looking for something more appealing? Attention grabbing images without substance are never good enough. And finally, which images get the longest attention, really inviting the observer to explore the entire image in detail?

At the end of your evaluation, take a look at the most observed images, and try to find out what they have in common, and what makes them so interesting. Compare them to the images that were less noticed, and analyze the difference. This revealing and sobering exercise will not just demonstrate the significance and importance of image quality, but it will also provide many clues on how to improve your images, and guide your photographic development.

Negative Quality

The first steps towards technical quality are taken during the process of image capture. This involves the selection of the most suitable camera, film and film format, focal length, lens aperture, as well as accurate focus and appropriate depth of field, shutter speed and, potentially, contrast enhancing filters.

It is quite possible to create a decent print from a mediocre negative, employing some darkroom salvaging techniques, but an excellent print can only come from an excellent negative. Aside from focus and adequate depth of field, film exposure and development are the most significant controls of negative quality, and a good negative is one that comes from a properly exposed and developed film.

The photographers of the 19th century were already well aware of the basic influence of exposure and development on negative quality. They knew that the shadow density of a negative is largely controlled by the film exposure, whereas the highlight density depends more on the length of development time. They summed up their experience by creating the basic rules of film exposure and negative process control:

4.   Expose for the Shadows
Proper exposure ensures that the shadow areas have received sufficient light to render full detail.

5.   Develop for the Highlights
Proper development makes certain that the highlight areas gain tolerable density for the negative to print well on normal grade paper.

Print Quality

The printing process is the final step to influence photographic quality. At the printing stage, all image-relevant detail, captured by the negative, must be converted into a positive print, in order to produce a satisfying and convincing image.

To complement the subjective image quality requirements mentioned above, the experienced printer follows a structured and proven printing technique, and makes a selection from available paper choices, which appropriately support the subject and the intended use of the image. Typical selection criteria include, paper thickness, surface texture and the inherent image tone.

© 2006 by Keith A. Williams, all rights reserved

In addition, technical print quality involves controlling adequate image sharpness and ensuring the absence of visible imperfections, possibly caused by stray, non-image forming light, or dust and stains. The printer is well advised to make certain that safe-lights, enlarger, lenses and other printing equipment are kept at peak performance levels.

Nevertheless, subjective print quality is predominantly influenced by print exposure and contrast, which is rarely limited to overall adjustments, but often requires local optimization, including laborious dodging and burning techniques.

Excellent print quality is required to support the visual expression of a valuable photograph. An interesting photograph, well composed and filled with captivating impact, but poorly executed technically, does not do the subject or the photographer justice. A photograph of high technical quality has excellent tonal reproduction throughout the entire tonal range. This includes the following:

6.   Create Brilliant Highlights
Specular highlights have no density and are reproduced as pure paper-white, adding brilliance. Diffuse highlights are bright and have a delicate gradation with clear tonal separation, without looking dull or dirty.

7.   Optimize Midtone Contrast
There is good separation, due to high local contrast, throughout the midtones, clearly separating them from highlights and shadows.

8.   Protect Detailed Shadows
Shadow tones are subtle in contrast and detail, but without getting too dark under the intended lighting conditions. The image includes small areas of deepest paper-black without visible detail, providing a tonal foundation.

Final print quality is subject to every step in the photographic process. In the preparation phase, quality depends on a successful concept, careful composition, and the right selection of negative format, film material, camera equipment and accessories. In the execution phase, quality depends on subject lighting, film exposure, contrast control and the skilled handling of reliable tools. Finally, in the processing phase, a ‘perfect’ negative is made to create a ‘fine’ print.