Photography, Old & New Again

Photography, Old & New Again

By John Fleischman, Robert Kunzig|Friday, February 01, 2002
RELATED TAGS: LIGHT

In 1847 one of the first daguerreotypes of an operation wowed viewers with its realism. A century and a half later, a new generation of holograms by optical engineer Yves Gentet—such as this one of a New Guinea beetle from his private collection—has much the same impact.
Photograph by Stephan Schacher
In an era when amateur shutterbugs can tinker with images from digital cameras on a computer screen, then instantly print them out on fine photo paper, one might think the future of photography is obvious.

One might be wrong. On the following pages, we offer two unusual reports of revolutionary developments in the field—one resuscitated from 19th-century oblivion, the other too futuristic to believe.



The Daguerreotype Revival
By John Fleischman
Photography by Brian Finke

Sunrise is still an hour away on this short winter's day, but mike Robinson is already hard at work in the basement of Massachusetts General Hospital in Boston. Steadying a velvet-faced wooden paddle on a work table, he rubs a small, silver-clad copper plate along the buffing surface again and again. His eye is on an electronic timer. Five minutes on the velvet buff, he says, then five minutes on the buckskin buff, repeat for half an hour, then another five minutes with iodine and bromine "sensitizing" boxes before three daguerreotype plates are camera-ready. I check my watch. It's going to be close.

Above us, on the fourth floor of the hospital, David B. Bernstein, chief resident in anesthesia and critical care, is getting ready for his first procedure of the day. He will induce a state of general anesthesia in a 43-year-old woman, after which surgeons will remove her gallbladder through a tiny incision in her abdomen, using endoscopic cameras and surgical instruments. If all goes well it should be an utterly routine procedure, except for one twist: In the far corner of the operating room, Mike Robinson will be making a daguerreotype of Bernstein inducing anesthesia.

The occasion is a scientific reunion of sorts, a meeting of two disciplines that were separated at birth long ago. On October 16, 1846, the world's first public operation under ether anesthesia was performed in this hospital, in a surgical theater known thereafter as the Ether Dome. It was an event to which we owe much of modern medicine. Before anesthesia, the best indicator of a surgeon's skill was speed (the Englishman James Syme was timed in 1834 amputating a leg at the hip in 90 seconds). After anesthesia, surgeons could operate for hours, and patients no longer had to be dead drunk or restrained by a straitjacket. Before anesthesia, surgery was dangerous and painful. After anesthesia it was just dangerous.

The discovery of ether was an international sensation. So within weeks of the first successful ether operation, Mass General, mindful of its historic role, hired the Boston firm of Southworth & Hawes to take a series of daguerreotypes. In the best-known plate, the camera looks down from the Ether Dome's steeply descending rows of seats into the stark, semicircular surgical pit. The patient, wearing only a cotton gown and wool socks, sprawls on the table unconscious, awaiting surgery on his leg. Physician John C. Warren and his colleagues are in street clothes—somber frock coats, florid satin vests. They wear no masks, no gloves, no surgical gowns, and have plenty of whiskers. Louis Pasteur is a dozen years from his first major discoveries about bacteria, and Joseph Lister nearly 20 years from his operations under sterile conditions. But in 1847 ether is a great leap forward, and these Boston doctors, holding as still as they can manage, know it.

Shooting daguerreotypes requires 500 times more light than shooting with modern film, so exposures can last a minute or more. To keep from smearing the image, subjects are held still by an antique cast-iron head stand.
Even as the doctors are giving birth to modern medicine, Southworth & Hawes are bringing into the world another definitive modern art: news photography. Their daguerreotypes weren't intended as commercial journalism (no American newspaper would directly reproduce a photograph until 1880), but this is one of the first uses of a camera to record an event in progress and not just a group portrait or a staged "photo op." The patient is ready. The cutting is about to begin. Dr. Warren steadies himself, his hands on the patient's leg. In the background a young surgical attendant in shirtsleeves stands by, ready to spring forward with the first scalpel.

Daguerreotype exposures were long, the mercury they required dangerous, and the plates fickle. Few daguerreotypists felt confident enough to work outside their studios without control over light, chemistry, and most of all, their subjects. How did Southworth & Hawes do it? Until recently such questions were best left to daguerreotype collectors, photohistorians, and a handful of others with a taste for the antiquated. Then in 1990, the George Eastman House in Rochester, New York, organized its first daguerreotype workshop. The Internet spread the news (ironically, daguerreotypes make great JPEG files: A backlit monitor simulates the effect of light scattering off the plate's silver background), and a very small revival began. Today there are even a handful of professional daguerreotypists.

Mike Robinson is one of the most adventurous, which is why he is handbuffing his plates in the basement of Mass General this morning. Robinson has made more than a thousand "dags" since taking a 1997 Eastman House workshop. He has perfected his art by trial, error, and creative scrounging. He doesn't have much choice. Although he would love to nip down to a local camera shop for some sensitizing compounds, no one stocks Gurney's American Sensitive anymore. Finally his beeper sounds. The last plate passes muster under a raking light. Robinson moves to a darkroom where he has parked his two sensitizing boxes. Their tops are sliders. Robinson latches a plate into the holder and, sliding it forward to expose the buffed metal to the tiny iodide flakes inside, starts counting under his breath. At room temperature iodine sublimates out of the flakes, rising in a vapor that reacts with the pure silver on the plate, creating an extremely fine layer of silver iodide—a photosensitive halide. This chemical layer gives the daguerreotype a degree of resolution far beyond that of any commercial film or pixel scanner.


Robinson runs out his count, snaps the slide back, and studies the plate for a telltale golden color. Satisfied, he transfers the plate to the bromine box and repeats the slide and count routine. Bromine is "faster" photographically, he explains, but too much bromine wipes out contrast. He orders the overhead lights off and withdraws the bromine slider under a red safelight. This light would still fog most modern films, but dags eat light: Even the fastest plates have a light sensitivity eight or nine f-stops slower than ASA 100. Robinson snaps the finished plate inside its light-tight holder. Thus he has sensitized three plates for the coming shoot, varying the times to bracket the exposure.

"This is the most demanding process I've ever done," he says, stretching out the predawn kinks. "It's also the most confounding thing I've ever done. With a dag, when something goes wrong, you don't have a clue. Just at the end you don't have an image." There are so many variables and no warnings if something has gone awry. Fortunately it's too late to worry, so we load up and move out.

Upstairs in the operating room, 20 minutes later, Bernstein cups a black rubber mask over his patient's face and lets her breathe oxygen for a few minutes. Then he settles the back of his head against an antique head stand. Because daguerreotypes drink in so much light, exposures have to be extraordinarily long: 25 seconds, 50 seconds, and 75 seconds in this case. The stand—a cast-iron monstrosity with a round, flowery base and a pair of adjustable tongs on top—steadies Bernstein's head and keeps him from smudging the image. Robinson inserts a sensitized plate into his camera—a meticulous rosewood reproduction of an antique once lent to Robinson—and withdraws a slide to let in the light. During the longest exposure, the beep of the heart monitor falls into sync with Robinson's voice, calling out the seconds. "Done!" Robinson cries, capping the lens. Then Bernstein switches the patient's IV to an opioid and a sedative, and she softly drops away to unconsciousness.

Out in the hallway, Robinson strips off his disposables and hurries to the lab. Once there he lights an alcohol spirit lamp under a pot of liquid mercury, filling the developing box with mercury vapor. Then he places the exposed plate over the vapor. "Now come the longest two and a half minutes in photography," he says. When the timer beeps, he pulls the plate out and gazes at it. There is something on the plate, he says, but it's still ephemeral. "The books say the latent image is as fragile as the dust on a butterfly wing. You could wipe it off with your finger."

The dust is silver. Inside the camera the focused light strikes the halides, sending an electric current flowing through the crystalline structure. Where the light is strongest, the charge is strongest. The stronger the negative charge on the plate, the more positively charged mercury vapor condenses onto it. The mercury washes the silver out of the halides, solubilizing and amalgamating it into free silver speckles. That's the fragile dust that marks out the exposed areas.

The plate goes into a sodium thiosulfate solution to dissolve the unexposed halides; it's rinsed with water and then washed with a gold chloride solution that's heated by an alcohol lamp. One by one the larger gold atoms displace the smaller atoms of free silver on the surface, creating more contrast. The fixed image is stable and durable.

The finished daguerreotype is a jeweled, one-of-a-kind object, no bigger than a hand mirror and shimmering with an eerie light. In a conventional photograph the image is embedded in the paper. Your eye reads the light reflecting off the white paper surface. In a daguerreotype the white areas are the silver/gold speckles that scatter light in all directions. The greater the scatter, the whiter the light looks. In the black areas the light bounces in and out at the same angle, reflecting very little. The light scatter makes a daguerreotype appear somewhat three-dimensional.

Robinson takes the plate by the edge gingerly and turns it to catch the light. My goodness, there is a tiny Dr. Bernstein in a tiny operating room, performing anesthesia. I look up. Robinson is grinning from ear to ear. I think of a London newspaper that heralded the ether news in 1846: "We Have Conquered Pain." What marvels, then and now.



The Hologram Revolution
By Robert Kunzig
Photography by Stephan Schacher

"They cannot be called copies of nature, but portions of nature herself," Samuel Morse declared. "a great legion of human faces," Walt Whitman wrote. "An immense Phantom concourse—speechless and motionless, but yet realities." In St. Petersburg, Russia, some people were afraid to even look at them, one photographer wrote: "[They] believed that the little, tiny faces of the people in the pictures could see out at them."

True, that was more than a century ago, but if the innocent wonder of those who saw the first daguerreotypes seems incomprehensible now, here is a place where you can recapture it—in the rue Dubourdieu, on the outskirts of the old center of Bordeaux, France. On the third floor of a building that houses a health clinic, down a dark hallway, in a reception area outfitted with secondhand furniture, sits Yves Gentet, a lanky young optical engineer who has invented something amazing. Next to him sits his younger brother Philippe, who came to work with Yves a couple of years ago. Before then Yves worked here alone for six years, with his lasers and his jars of animal gelatin (more on that later) and a No Trespassing sign on his office door. Yves's hangdog eyes appraise you as you appraise the walls of his reception area. They are covered with his holograms.

The walls are an immense concourse of phantoms, of people trapped in amber. There is a Laotian model dressed in a traditional dancing costume, every ornate detail popping from the frame. There is a little girl in a striped shirt, eating a cookie, the crumbs falling from her mouth. If you step to one side you see, behind her raised arm, the collar that was hidden before, with its tiny embroidered chick in a sailor suit; if you bend down and look up you see, above the level of the frame, her mother's smiling eyes. And then there is the box of butterflies, most impressive of all. It is as detailed and as vibrant as reality—but the real box is in the Bordeaux natural history museum. This is just a film sandwiched between two thin sheets of glass.

"It's the dream of holography realized," says Jacqueline Belloni, a chemical physicist and specialist in film emulsions at the University of Paris South. "Whether you're a specialist or not, it's a shock when you see it." Belloni was so flabbergasted when Gentet showed her his butterflies that she included them in a talk she gave at a conference on radiation chemistry. One physicist, who also happened to be a butterfly collector, wandered in late and asked why on earth she was lecturing about a box of lepidopterans. "He wouldn't believe me," Belloni says. "He had to touch it himself." The butterflies seemed not copies of nature but portions of Nature herself.

A hologram made by Yves Gentet for the Musée de l'Optique in Biesheim, France, has none of the oil-smear-like inaccuracy of standard holograms. From almost any angle, it captures life perfectly in three dimensions.
Half a century after holography was invented by a British-Hungarian physicist named Dennis Gabor, it still seems mysterious and magical. Partly this is because well-done holograms are so rare; partly it is because the underlying science is convoluted. "My father was a mechanical engineer in Brittany and very intelligent," Yves Gentet says. "But I had to explain it to him many times. And he asked me the same questions many times." Along the way, though, Yves got the hang of explaining it.

Every light wave has three properties. It has an intensity determined by the height of its crests. It has a color determined by the distance between crests—the wavelength. And it has a direction of travel. Daguerreotypes and black-and-white photographs record only variations in intensity; color photographs record variations in wavelengths too. But holograms alone capture light's third property. By recording the direction that light waves travel as they bounce off an object, holograms let us see that object in three dimensions.

Most holograms are monochromatic—they record the intensity and direction of light waves but not their wavelengths. But in the 1960s a Russian physicist named Yuri Denisyuk invented a technique that makes it possible to create holograms in full living color—to record all three properties of light at once. In Denisyuk holography, red, green, and blue laser beams can be mixed together and shone through a transparent holographic film onto the object. The light reflects off the object and back onto the film, where it runs into the original beam. The colliding beams interfere with one another, creating bands of light and dark stacked roughly parallel to the film's surface (see diagram).

Now comes the magical part: At millions of points on the holographic film, those bands are recorded as stacks of semitransparent mirrors, each tilted at a slightly different angle. When you shine natural light on the developed film from the same direction as the original laser beams, all those mirrors reflect light at precisely the same angles at which it originally bounced off the object. Thus when you look at the film, you see the object floating behind it, in full 3-D glory. Even better, you see it in full, true color. The spacing of the mirrors in each stack is such that each stack reflects only the wavelength of light that created it; the other wavelengths are canceled out.

Simulated 3-D Gentet makes a color hologram by shining mixed-color laser light through a transparent holographic film onto the object, in this case a red ball (left). Reflected light travels back through the film, where it interferes with incoming light of the same wavelength, creating light and dark bands (inset). In the light bands, spaced half a wavelength apart, the film's silver bromide is transformed into a series of semitransparent metallic silver mirrors. When Gentet shines natural light onto the finished hologram (right), those mirrors reflect light of the exact color and at the same angle as the object did at that point; the same process occurs for objects of other colors in the picture. Millions of tiny mirror stacks, with different orientations and different spacings, create a full-color 3-D image.
Graphic by Matt Zang

That's the idea, anyway. In practice, until Gentet, no one had made a holographic film that could do it justice. The best-known holographic film, made by Crown Roll Leaf and a few other companies, is used to create "rainbow" holograms recorded on polyester film. You've seen that film on credit cards, but you were in no danger of thinking the eagle was real. It just isn't light sensitive or color faithful enough to re-create reality. Another type of emulsion, bichromate gelatin, is even less light sensitive, but it has been useful in holographic readouts such as those that enable fighter pilots to keep their eyes on the enemy rather than the fuel gauge. Gentet worked on such a system at Sextant Avionics in Bordeaux until 1992, when his lab folded and he was laid off.

At the age of 29, Gentet was left with a career as a freelance holographer, and he decided to make the best of it. Several French companies helped him out with the lab space in Bordeaux. Gentet spent his first couple of years there building all his own equipment from scratch, in particular a portable holographic portrait camera that he envisioned as his cash cow. He had just about finished it when Agfa, the sole manufacturer of the film his camera required, decided to get out of that business. Having invented a camera Gentet found he now needed to invent a holographic film as well.

Gentet's years of teaching himself film chemistry and tinkering alone in his lab have resulted in an emulsion he calls Ultimate. Its basic structure is that of ordinary black-and-white film: an emulsion of silver bromide grains, which are very light sensitive, dispersed in animal gelatin. When light strikes the grains, the silver bromide is converted into metallic silver—the stuff of mirrors. The main difference between Ultimate and other emulsions is that its silver bromide grains are extremely fine—around 10 nanometers across, or 1/10 to 1/100 as big as the grains in ordinary film. The fine grains allow Ultimate to record tremendous detail. They also allow it to record red, green, and blue simultaneously in a single emulsion layer, as interdigitating stacks of tiny mirrors.

Gentet won't say how he makes the emulsion; none of his techniques are protected by patents. "We've perfected the emulsion that everyone has been looking for for 30 years," he says. "It's savoir faire—know-how." But it's not as if he is asking people to take his assurances on faith. If seeing is believing, then standing in his reception area and looking at his walls, you have to believe him.

Yves Gentet adjusts an optical bench in his lab in Bordeaux, France. The bench holds some 120 optical instruments used in the making of Gentet's most complex multichannel holograms.
Two summers ago, the Gentet brothers took their butterflies and a few other images to a holography conference in Austria. When it came time for their talk, the trade newsletter Holography News reported later, "140 seasoned holographers made a collective, awed intake of breath." Afterward, Philippe says, "the room emptied as people came to look at our holograms." "People were subjugated," Yves recalls. "All these experienced holographers put their hands behind the glass plates as if the images were a mirage. They were glued to them."

The triumph was long in coming: Since Yves invented Ultimate, the world has not exactly beat a path to his "hole in Bordeaux" (his words). Gentet thinks his holograms would be a perfect way to make a replica of Chauvet Cave, the site of spectacular prehistoric paintings that the public isn't allowed to see, but he can't get an appointment with the proper authorities to present his idea. He has proposed setting up a portrait studio at Disneyland Paris to create a gallery of visiting celebrities, but the negotiations have stalled. The basic problem, Gentet thinks, is that he has great holograms but no hologram factory, and French investors are too risk-averse to build one. He and Philippe have been thinking of immigrating to Quebec, where it may be easier to find willing investors. Their father, now retired, is ready to go with them.

Lately, though, things have been looking up. Gentet has found an American partner who has the machinery to copy an Ultimate master onto a polymer made by DuPont. For reasons Gentet doesn't fully understand, the results, though not of Ultimate standards, are far superior than if the polymer were used to record the hologram in the first place. The DuPont copies can already be cranked out on an industrial scale, and the same may soon be possible with Ultimate itself. Meanwhile, this past November, Gentet's holograms won two major awards from the International Hologram Manufacturers Association.

Somehow Gentet's images will get out; they're too powerful to remain cooped up in the rue Dubourdieu forever. Even Gentet himself is spooked by them sometimes. "When I made a portrait of my father, I couldn't sleep that night," he says. "It was the shock of having my father's head in a box."

The Daguerriean Society site illuminates the art and the science behind it: www.daguerre.org.

Yves Gentet's Web site has information about Ultimate and how to purchase a Gentet hologram: perso.wanadoo.fr/holographie.

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