Immersion

Hidden behind a viewfinder
("The Photojournalist,"
Andreas Feinenger's
portrait of  Dennis Stock)

Hiding behind a camera isolates a photographer from their subject, whatever that subject might be. There is a way to break through the isolation and though it should be obvious, many never try it.

It seems like forever since I last wrote concerning the mechanics of composition. And you may not remember that when I first approached the subject I said that there have historically been three main modes of accomplishing this. Well...I actually touched on only the first two: the groundglass and the viewfinder. Hmmmm...whatever happened to that missing third?...and what even was it, anyway?

Whether looking at a surrogate of the final photograph on a groundglass (or its modern digital counterpart), or at a limited view of the world through a viewfinder, a photographer is usually isolated to some degree from the world he hopes to image. However, there is a third way of composing the image that actually connects the artist to the subject and immerses them in the world.

Hidden behind a groundglass

In the 1920s and 1930s, cameras had sufficiently progressed technologically to where they were relatively portable, light-weight, and technically simple to operate. Smaller, faster photographic materials ("film") coupled with faster lens systems also had a major impact. These factors had the distinct effect of allowing the photographer to leave the studio behind and begin finding photographic adventure "on the street." It was a monumental leap for the photographic artist to see her art and craft as not simply that of portraiture and still-life in the studio or even of landscapes (if she dared venture out of doors). She could now join the rest of humanity where they lived much of their lives– in action and on the street. This was the beginning of what we would today call photojournalism.

The groundglass obviously became a totally useless antiquity in this new setting. And even though most cameras still contained a viewfinder, those who looked for the real breath of life on the street (and wherever life happened) couldn't be confined behind the optical system of a viewfinder. They preferred to walk among their people, maybe with the camera held at their waist instead of raised to their eye, looking their subjects directly in the eye– eye to eye.

This visual communication allowed the artist to be in real human relationship with their subject, however brief that might be. The subject now saw the photographer as another human being rather than some kind of bio-opto-mechanical-hybrid monster. And the photographer could now see their subject as not simply some image to be composed within a little rectangular frame, but as a real, living and breathing person who existed within a larger environment.

This alternative mode of composing an image abandons the precision of framing and composition that is offered by the groundglass and the viewfinder, but it definitely makes up for this deficit with increased intimacy and immediacy with the subject. This mode takes some practice to get right, but muscle-memory will eventually take over and make "aiming from the hip" second nature.

Try taking photographs with your camera at waist level— don't worry, with modern cameras "film" is cheap, no, FREE! Take as many as you like, attempting to frame the image you desire. When your practice sessions are over you can easily discard your attempts. Do this often, over a period of weeks and months, and you will see a steadily improving ability to point your camera from waist-level at anything you are looking at and capture an image that accurately frames the one you imagined.

A side benefit of all this is that you can also gain a deepening aesthetic sense that can free you from overly depending upon precision and analysis. Enjoy your new-found freedom!

Finding the View

Front of an optical viewfinder system
(subject side)

The groundglass was an early and major innovation in composing the photograph and it was soon followed by the viewfinder. While the groundglass was a "focal" (image producing) type of system, the viewfinder is a distinctly "afocal" (non-imaging) scheme. The point of this particular compositional aid is not to produce a duplicate, or surrogate, of the photographic image, but to allow the photographer to continue looking "out into the world"– with the additional assistance of a synthetic framing boundary overlaying the visual scene. This artificial frame represents and marks the region of the scene that will be captured by the actual photograph.

Rear of optical viewfinder system
(eye side)

The first (and most rudimentary) viewfinder was a simple set of wire frames through which the photographer viewed the scene directly with his eyes, with no intervening lenses or other optical components. This simple metal framing device was something akin to the aiming sight on a rifle or gun. It allowed the photographer to retain a fairly intimate connection to the real world while, at the same time, having some objective means of properly aiming the camera and understanding what the photograph's ultimate composition would be. The photographer simply lined up the two metal frames with each other and then observed what part of the scene appeared within the frame. It was simple, quick, cheap, and effective– a very attractive combination of attributes.

As photographic hardware developed over the decades optical technology became not only more sophisticated but less expensive and, therefore, more available. This made it possible for the viewfinder to advance from a simple pair of geometric framing devices to a true optical system comprised of multiple optical components. The optical viewfinder system would allow placement of the camera close to the photographer's eye, and through which the photographer would be able to view the scene, with the ultimate image conveniently framed. The effect of this was something like viewing the world through a telescope or binoculars, albeit with a rectangular rather than circular framed field of view.

Looking into viewfinder

The optical nature of this viewfinder system also allowed many new additions to what this device was capable of. Precision reticles could be inserted into the interior of the viewfinders that would allow changing the field of view to match whatever lens (for example, wide angle or normal) happened to be placed on the camera. The optical components of the viewfinder could also be mechanically coupled to the focusing system of the camera's main lens to help the photographer know when the camera was properly focused without moving his eye from the viewfinder. As practical zoom lenses were eventually invented and added to the photographer's bag of tricks, the viewfinder became a zoomable device as well, with its zooming capability coupled to the main lens's zoom state, thus providing the photographer with an accurate view of the photograph's composition.

As cameras became more and more electronically instrumented, the display of the camera's exposure state (shutter time, lens aperture, and film speed) was ultimately incorporated into what could be seen within the viewfinder. At this point the photographer no longer had to take his eye away from the viewfinder to adjust the camera settings. He could remain looking at the composition of the photograph while simultaneously and actively manipulating the exposure state, lens focus, and zoom of the camera. This was a powerfully attractive capability, but as with most powerful technologies there was a price to be paid.

Scene framed in viewfinder

Just as the groundglass caused earlier generations of photographers to retreat from the real world under the isolation of their blackout cloth, this new generation would be isolated behind the camera body, with their open eye pressed up close to the rear of the optical viewfinder. The world beyond the photographer (the subject) could not now maintain true eye contact with the photographer, who began to appear as something of a mechanical man– his head and face replaced by a black rectangular box and a glass lens as his Cyclopean eye, staring coldly out into the world.

It would seem that regardless of the technology involved, there is always a tendency for the photographic artist to be removed from their immersion in the real world and be inserted into an isolated, artificial world. And perhaps that is the bain of all artists– that their art would attempt to dominate and replace the real, objective universe and the real human lives within it with a world of their own making. The power and beauty of artful creation can be seductive– for the creator as well as the beholder.

Photographic Purity– (Distortion or Not)

Panoramic photographs have their own brand of geometric subtleties (some would call this "distortion"). Much of these effects are because of the extremely wide angle of view (as much as a full 360 degrees) that panoramics rely on. When photography was relegated to capturing a view that simulated looking through a window, the geometry was narrow enough to keep geometric effects below the surface.

As long as a panoramic photo is captured in the "conventional way" (with its plane of rotation parallel to the horizon) so-called distortion is minimal- maybe even undetectible. When that plane begins to tilt away from level, distortion begins to be perceived. If a full 360 view is captured, any planes or lines that are parallel to the horizon appear as a sinusoidal curve.

HARVEST WAVE, © Bill Brockmeier, all rights reserved

This curving of features that otherwise should appear as lines is entirely a consequence of geometry, rather than a deficiency of the imaging system. Imagine that the rotation of a panoramic camera setup sweeps out a cylindrical view of space as it rotates through 360 degrees. If a planar feature in the view (the earth's surface/horizon, for instance) is perpendicular to the cylinder (the rotation is level) the plane will trace out a feature on the cylinder that is a straight line when unwrapped (which is what happens when the pano photograph is printed on a flat sheet of paper).

But if the plane (the horizon) is tilted with respect to the cylindrical view, and the cylinder then unwrapped, you will see that the traced out pattern is now a complete sine curve. The amplitude of the curvature (distance from peak to valley) is a function of the degree of tilt between the plane and the cylinder.

Well, enough on this. I believe I've beaten this dead horse more than sufficiently, and I think you can see that "distortion" is really a matter of personal perspective. What one person might consider a distortion of physical reality is merely one of the myriad (NOTE for Michael: "myriad" is a Greek word meaning, specifically, "ten thousand") ways of reasonably mapping or interpreting the real world onto a finite piece of a two dimensional surface. I don't believe anyone can categorically or authoritatively state that any one particular mapping or interpretation is to be absolutely preferred over another.

I believe it is ultimately important in the arts (of which photography is certainly one) to remember the treachery of images– that the image (the artistic creation) is NOT the reality which inspired it. And it is good to remember that photographic "purity" is more a phantom than a reality...that "distortion" is really the foundation of the photographic arts rather than its bane.

Photographic Purity– (Building a Panoramic)

We've seen that distortion is built into the process of producing a conventional photographic image. If we take a few regular photographs from the same location, slightly rotating the camera for each frame, we effectively cover a greater field of view with the shots. If the shots slightly overlap each other at the sides, we ought to be able to easily combine  them to produce a single wide-angle image.

Unfortunately, this process will not work because the built-in distortion of the camera lens causes all features in the view to change shape when the camera points in a different direction. When a particular feature is on the right side of the field of view it's one shape, and when on the left side of the field of view it's a slightly different shape. So, when the right side of the first image is overlaid on the left side of the second image, the shapes do not match. This results in either ghost images, missing information, or otherwise mismatched overlaps in the final pano image.

For a proper, undistorted blending of conventional camera shots into a wide angle panorama, the built-in distortion of a standard camera lens must be eliminated, or at least minimized. Once the distortion has been removed the separate frames may be simply overlaid on each other, with the overlapping parts of the images matching well and the images blending into one.

Panoramic sequence of nine frames that have been geometrically remapped to remove camera lens distortion

In the days before modern digital computing, this distortion elimination was nearly an impossible task. Now, this process has become not only possible but even fairly simplistic to the user. Although it seems easy from the outside of the computer, there are actually many billions of calculations and transformations being carried out for a single panorama to be compiled.

Photographic Purity– (Distortion By Intent)

The whole idea of producing a precisely rectangular  image of a known rectangle in the real world is suspect, and actually a distortion of reality. I say this because a rectangular object cannot truly appear as precisely rectangular.

At first blush this sounds counter-intuitive. You might say: "Of course rectangular objects look rectangular- what else would they look like?!" But do they? Under most circumstances, rectangular objects appear mostly rectangular, but widen the view that a rectangular object encompasses, and the picture becomes clearer.

Imagine that you are standing in front of a very large one story building- let's say that it is 10 feet high, 200 feet wide, and you are 20 feet away from it. The left end of the building stretches way off to the left, and the right end to the right. Those ends of the building appear very small, while the middle of the building right in front of you appears quite large. How then, can the front of the building appear as a rectangle?

In fact, the top of the building and the bottom of the building must actually appear as curved edges, with the two curves farthest apart in the middle, and closer together at the two distant ends. This is a simple consequence of the fact that closer objects appear larger and distant objects appear smaller. For a rectangular object centered on the direct axis of view, this causes all sides of the rectangle to appear slightly bulged out away from the center.

While this scenario is certainly an extreme example, it is still true for all other situations, just to a lesser degree. This is the effect that the built-in distortion in a camera lens attempts to mitigate. This lens design tries to force the object to actually be imaged as a rectangle, when, as we've already seen, it can't really look that way.

For the most part, this purposeful distortion in a camera lens is actually a benefit (why else would lens designers go to such great lengths to design them this way?). But when attempting to reconstruct a panoramic image from separate camera images this built-in distortion makes the effort problematic. I'll look at this issue in my next post.

Image by camera lens with built-in distortion to
produce precisely rectangular shape

View of rectangular object as it might actually
appear as a consequence of geometry

Photographic Purity– (Geometric Distortion)

Another question that occasionally comes up when people are viewing my art at shows revolves around something they usually refer to as "distortion." The question commonly sounds like this: "I thought that panoramic photos were usually distorted, but these don't look distorted," or: "Is that hill really there, or is that just distortion?" I believe that what they are concerned about is whether or not the photograph looks something like what they would have seen if they had been standing there as I took the photograph.

SEA OF COREOPSIS, © Bill Brockmeier, all rights reserved

The answer to these questions is not a simple one. Much of the problem in answering them stems from the fact that the basis of photography is the attempt to map visible features in the three-dimensional real world onto a finite area, two-dimensional plane. While that may sound simple enough to the uninitiated, it is actually a very complex geometric and human perceptual problem. There is not a single way do to this mapping, but probably dozens of ways, with each method having its own merits and short-comings.

I won't bore you with the details of these dozens of methods, but many of them were devised over the past few centuries as the globe became circumnavigated and every far-flung corner of it became a goal of human exploration. At that time, it became important to be able to precisely represent this three-dimensional sphere we call "earth" on a flat piece of paper, so it could be easily rolled up and carried in a captain's quarters on a ship, or in the saddlebag of a horse-borne explorer. The profession of a cartographer was an incredibly demanding and important job.

When photography came along, this ability to conflate a three-D world down onto a simple two-D representation became an incredibly "easy" transformation to accomplish– automatic, in fact. The photographer didn't even have to think about it, the camera just "did it." But what determined the actual geometric transformation was hidden in the details of the optical system: the precise optical makeup of the lens system and the geometric relationship of the lens to the photosensitive plate (and its shape).

The devising and engineering of optical/lens systems has been a rich field of innovation for the past century and a half. Some of the world's brightest technical minds have been devoted to this pursuit. Their efforts at devising new lens systems have been aimed at things like sharper image focus (better detail), improved light-gathering ability, and decreased geometric distortion– whatever that means.

Lens designers have a very limited definition of what "geometric distortion" (or "image distortion") means. I won't go into what that specific definition is here, but it has very limited significance for most of the photographs that most people take. For instance, if one was trying to exactly reproduce the type on a printed, flat sheet of paper, this narrow view of distortion might be important. But if someone's portrait, or a distant landscape are more likely the subject, it's not clear that this "distortion" is an important consideration.

Most people don't know, and even most photographers don't realize, that most photographic lenses are actually designed with a certain distortion built in. It's easy to demonstrate this with almost any camera, and the more "wide angle" that a lens is, the easier it is to see.

Look through a camera's viewfinder, or at its digital display, and look carefully at some scene before you. Then, start panning the camera to the right. As the camera is in motion you will notice that objects in view will change their shape and size somewhat as they move from the right edge of the frame, to the center, and finally to the left edge. The real objects are obviously NOT changing in shape just because the camera is moving, rather, their image is different because it is passing through the lens in a different direction, thus revealing the lens's built-in distortion.

In both of the photographs below, the camera was placed at a point precisely perpendicular out from the center of the clock. The only difference in the two photos is that in one of them the clock was placed at the right edge of the camera's field-of-view, in the other it was at the left. Notice how the square of tiles immediately surrounding the clock is not square but trapezoidal in nature, and that in one of them the top and bottom lines converge to the left and in the other they converge to the right— their shape has changed. Remember that the location of the camera for each photograph was identical, and that only its direction changed.

clock at right edge of camera's field-of-view

clock at left edge of camera's field-of-view

This distortion is a by-product of the lens designer's determination that if the photographer is taking a photograph of something that is known to most people to be rectangular in nature (and that is fairly far away, and exactly centered on the camera's optical axis, and precisely perpendicular to that axis), the final photographic print should also display a precisely rectangular feature. Although that sounds reasonable enough, this is definitely a distortion of the truth, and, in fact, rectangular objects cannot really appear precisely rectangular, even if the restrictions noted above are followed.

I'll leave the proof of this final assertion for my next entry.

Photographic Purity– (Beyond B&W: Color)

Black and White photography transitioned to color imaging before most people alive today can personally remember. Bill Watterson, in his Calvin and Hobbes creation (probably the high-water mark of daily cartoon strips), probed this technological shift with an amusing and thought-provoking perspective. Out of respect for Watterson's copyrights I won't provide a direct link here to this particular strip, but you can find it out there if you search for it.

When the ability to capture "true color" images arrived, this new tool was widely seen as nearly miraculous and bringing the viewer ever closer to a "true" recreation of the original scene. This shift from B/W to color was almost (but not quite) as profound as the shift from painted images to photographs had been most of a century earlier. Instead of recording only values (light/dark), this new capacity could acquire the various hues and saturation levels in a scene as well. For nearly the first century of photography, paintings always had the upper hand when it came to coloration– photographs just could not compete in this arena. Now, with color added to the mix, the sky was nearly the limit. In fact, the sky no longer had to suffer the dreary limit of endless stretches of gloomy gray, but could now burst forth with the beauty of its truly blue self.

EARTH AND WATER INTERWOVEN, I, © Bill Brockmeier, all rights reserved

Of course this ability to record the colors apparent in a scene has to be closer to the reality of the original...or does it? It would be instructive here to ask a simple question: "What is color, anyway?" It might come as a surprise to find out that color is not actually a physical parameter, but, in fact, is simply a human perception, a construct of the mind.

While one might say that color is just a matter of the wavelength of the light, this is stripping down the truth of color far too simplistically. There are actual, perceivable colors that don't even exist on the complete spectrum of "all the wavelengths" that are spread out from white light as it passes through a prism. And any specific, perceivable color can actually be created from an infinite number of possible combinations of different other colors. Even more amazing, it is possible for there to be two things that appear exactly the same color under one lighting condition, and yet appear to be dramatically different in color from each other in a different lighting condition (metamerism).

Here is a short list of conditions that can substantially affect the perceived color of an object:

• color of the light illuminating the object
• brightness of the illumination
• color of the object's environment/surroundings
• colors and intensity of light viewed previous to viewing the object
• color characteristics of any transmitting medium between the object and viewer

Most probably know that it is in the retina, the light sensitive back surface of the eye, that color is initiated when photons are preferentially absorbed by the different cone (color) receptors. While this is true, this is only the beginning (the barest beginning) of color perception. This is no simple RGB (red/green/blue) modeling of the light that is intercepted, as in a camera. The neural network of the retina takes this simple color "information" and already begins massaging it and reacting to it, before it sends it on to various locations in the brain, which further process these signals into a whole host of responses and outputs, gaining even emotional and visceral components along the way.

While the truth of color perception is highly complex and cannot be quantified unambiguously, what about the "simple" RGB (trichromatic) model used by photography? It turns out that even if we restrict ourselves to discussing this stripped-down technological version of "colors" it is a complex issue. First, there is the camera that takes the complex mix of light and turns it into an array of values that represent the "original colors." Of course, these values are necessarily compared to some "reference white" (would that be an incandescent lamp? a fluorescent lamp? or maybe natural sunlight...and at what time of day?).

The numerical values that are produced by this method are also limited in various ways. First, there is the sensitivity/detection function of the three separate color channels of the camera (basically, the filter transmission curves of the camera's detectors). Then, there is the dynamic range of the values (lightest to darkest) and the size of the steps from one value to the very next. There is also the issue of color gamut– how much of the totally perceivable color "real estate" can be covered by these numerical representations?

Finally, when these numerical values representing the colors in an image have been determined, how will the image be reproduced so it can be seen? Here, the loop is closed by somehow converting the values back into color representations either emitted by the light of a digital monitor, or by the density of different colored ink droplets on paper media. In both these cases, the representations themselves convolve the dynamic range and color gamut limitations as mentioned previously for the camera. On top of that, there are now even more considerations that effect the final colors– things like color gamma in monitors; and for printed images, dot gain, media brightness and whitepoint, and illumination whitepoint, color rendering index, and brightness. And if that wasn't enough, high-end photographic printers now boast of as many as ten or twelve different ink colors to represent those three original RGB colors. As you can see this is a highly complicated issue, and it is an amazing thing that the whole system works as well as it does.

It's clear that there really is no such thing as photographic "purity" when it comes to color. Attempting the photographic reproduction of the "original colors" of a scene may (or may not) be a worthy goal to strive for, but it is simply not possible today (and really never will be). And that's OK. After all, this is an art, and van Gogh did not mix his colors like Gauguin did.

Photographic Purity– (B&W vs Color)

In my previous post I mentioned that the basis for photography was producing "an analog of what the original subject 'looked like.'" That thought was a kind of off-the-cuff remark, but thinking about it again, I believe it now even more strongly. It is significant that a photograph is aimed not at simply reproducing a physical duplicate of the original, but, rather, in producing (or re-producing) a human perception ("...looked like"). The photographer may be interested in reproducing/conveying whatever her own human perception was of the subject at the time, or she may be interested in producing a particular and wholly new internal perception in the mind of the photograph's viewer (or both).

I believe this matter sets photography apart as an art, rather than as simply a science. There certainly is a place for photography's use as something closer to a science when it is used more simply as a documentary device. In my own work as an optical engineer, I sometimes use photography to purely document the external surface state of a material sample after it has been exposed to laser radiation. And its use in medical and forensic science to document both simple and complex systems and circumstances is invaluable. Even photo-journalism uses something of this documentary power of photography, but in this case, it is equally used to form a perception in the viewer and persuade.

When photography began, it's aim was an image that was composed of light and dark areas, to represent the light and dark areas that were seen in the original subject. This light/dark nature lacked any reference to the original colors in the subject– it was what we now call B/W ("black and white") photography. In this infancy of photography there was not much thought given to what the original colors might have been. At that time the only pigment available on the photographic artist's pallet was a single, simple stick of charcoal. Colors were not what mattered; only values mattered. These early innovators of photography probably never even imagined that photography would someday capture colors as well as values.

Today, there are very few people alive who can remember a time when there were only B/W photographs. And the days of choosing between an inexpensive B/W television and an expensive color unit are decades in the past. In this day, B/W photography is seen as sort of an avant-garde artistic technique, rather than the primitive progenitor of modern photography. B/W is now seen more often than not for its substantial artistic possibilities rather than as an older and cheaper form of photography. This is a good thing.

EARTH AND WATER, INTERWOVEN I, © Bill Brockmeier, all rights reserved

The considerable benefits that monochrome photography brings to the art are wide in spectrum and deep in subtlety– far too great to exhaust in this short article. However, I must at least mention its unique ability to bring the form and structure of an image's composition into clear focus. In some respect, it can offer also distinct abstract qualities to an image, somewhat distancing the observer from the original scene, and thereby bringing them into a closer interaction with their own (or the photographer's) thoughts, impressions, and emotions about the image.

With only tonal values present in the image, color can no longer distract the viewer from the image's underlying structure. This monochromatic vision is a very foreign way of seeing, and usually only experienced under extremely low light level conditions. Perhaps it is this foreign nature of the experience that helps us to see in more than a simply natural and commonplace way. Geometric interplay between various forms and shapes in the image can become paramount. Light and dark, airiness and weight, levity and gravity sing and dance a duet.

It is strange to think that in limiting our ability to see– by removing all color information– we can see things that may have been invisible before.

Of course the final irony in the whole thing is that B/W photography is not truly monochromatic. The white in a B/W image is what a physicist would refer to as "broadband" or "full spectrum" light. This is light that is composed, not of a single wavelength (color) of light, but, rather, of all wavelengths/colors. And even in the original capture of the image, all colors (not just one) came together to produce the image. Truly, "less is more" and "more is less."

Photographic Purity– (What is photography?)

As I show my work publicly, a frequent question I am asked is— "Do you digitally 'enhance' your photos, or are they 'straight' shots?" Although I think I know what they are generally asking, the real answer is not quite so simple as they might imagine.

What they probably want to know is whether or not I have intentionally used an image editor (like Adobe's PhotoShop) to "pump up" the photograph's color saturation, or contrast, or sharpness, or whatever. They want to know whether I am a photographic "purist" or not. Although I usually respond that "I try to keep the shot as 'straight' as possible," the answer to this question is still not clear cut. Maybe what we should begin asking is "What really is photography, anyway?"

TIME IS MONEY, OR IS IT AN ANGLE?, © Bill Brockmeier

Photography is the process of using the light energy that is coming from a subject to form some sort of physical image that is an analog of what the original subject "looked like." What I mean by "analog" is using one thing to represent another. For example, an "analog clock" uses the angular motion of the clock's hands to represent an amount of elapsed time. In this case, 30° of movement of the hour hand is used to represent one hour of elapsed time. Of course, that 30° is not the exact same thing as one hour, but it is a useful representation of it, since we can't actually see time.

In a similar way, photography aims to represent a view of an original subject by substituting some other "image" that is a function of, or is dependent on, the subject. The specific details of what this representative is, and how that transformation is made from the subject's light to an analog/photographic image, have varied greatly over the history of photographic technology. During most of this history, however, one particular transformation has been king: that of photosensitive silver salts.

From almost the beginning of photography, this process had as its goal the production of an "image" composed of analogous dark areas (due to microscopic particles of silver) that resulted from similar dark areas in the original subject (assuming a positive image). <<<The complexities of that process are far too deep to expound upon here.>>> And, conversely, the lighter areas in the image (resulting from light areas in the subject) were simply due to a lesser concentration of these silver grains, with the lighter substrate showing through to a greater degree. Images produced in this way were eminently recognizable as having a correspondence with the original subject.

It is important to keep in mind here that this "image" made up of silver particles is not actually reproducing the original subject at all. Although we can recognize a photograph of a railway steam locomotive, it is totally obvious that this photograph is NOT a steam locomotive! <<<see Rene Magritte's The Treachery of Images>>> Not only does the image totally lack the weight and substance of the original, it is only a two dimensional pattern, lacking the critical third dimension. At any angle of observance other than perfectly perpendicular, it quickly becomes obvious that the image is severely limited in realism (we won't approach holography in this discussion of photography).

THIS IS NOT THE INTERNATIONAL SPACE STATION, © Bill Brockmeier

On top of this, the brightness of each little area in the image cannot even begin to replicate the range of brightness exhibited by the real object. About the best the silver image can do is a ratio of brightness to darkness of about 100, while the eye can see a ratio of something more like 1,000,000, and the real object can have a ratio that is nearly unlimited.

These limitations are immense, nevertheless, the transformation of light energy into tiny silver crystals has been an eminently useful, and immensely successful, analogy. Eastman Kodak's billions of dollars, and probably hundreds of billions of photographs taken by the world's population over more than a century are a strong testimony to that success. And the creation of a whole new art-form, distinct and separate from painting, is credited to this transformation of light energy to a pattern of matter.

Then, we have the issue of light frequency/wavelength, or color, which we'll look at in my next post on Photographic Purity.