Using a shutter speed of 1/1600 of a second, I was able to stop time, and catch eight White Ibis in flight. Some fly directly at my lens, while others veer away. They seem to float through a screen of branches, making us wonder how they manage to elude them. These birds are part of a large mating colony that live among the trees in this vast swamp near the Florida Everglades.

Arcosanti is a prototypical city of the future being built in the Central Arizona desert. Designed by the 93 year old architect Paolo Soleri, it intended to someday house 5, 000 people. It has been under construction for 30 years. A small group of apprentices live, work, and study here – they provide the manpower to build Arcosanti. This apprentice was not working. Instead, he was working out on the basketball court set within the beginnings of what someday will be a massive vaulted town center. I caught him in silhouette just as he lofted a shot into the net. His arms are still raised as the ball slips into the net, symbolizing a moment of triumph that can be seen as the ultimate purpose of his apprenticeship.

I stopped this pair of Frasers dolphins as one leaps and the other plunges at a shutter speed of 1,2500th of a second, using a long 400mm telephoto focal length. The animals were quite distant, making them very small in the frame. I cropped in on them, and changed the image from a horizontal to a vertical. I placed the animals in the upper half of the frame, and left a long panel of water below them to intensify the nature of their leap and the plunge.

Some photographers enjoy working on waterfalls with a tripod, using filters to cut the light and slow shutter speeds to create a smooth, silky flow of water. I never carry a tripod for slow shutter work. Instead, I prefer to work on waterfalls in the opposite way – using fast shutter speeds to suspend the flow in a fragment of time, and creating form and shape in ways that express the power and energy of a nature. I made several hundred hand held images of Shoshone Falls, underexposing my photographs by two full stops, and spot metering on the sun splashed spots, causing the shadowy part of the flow to go dark. Later, in my post processing, I bring up the detail in those dark shadows, as I do here. This was my favorite image – my fast shutter speed of 1/640th of a second creates a lunging fringe of water that hurtles down upon the misty, brightly illuminated golden pool at the base of the image.

While photographing the unloading of a fishing boat in Fort Bragg’s harbor, I could not help but hear the screeches of some very angry gulls. I used a 400mm telephoto lens and significant cropping in post-processing to zoom in on the furious protagonists. I initially thought that 1/250th of a second shutter speed would be fast enough to stop the action, but these gulls proved me wrong. Their wings were moving in a blurred frenzy, probably a squabble over a stray piece of fish. I liked the blur so much that I did not even try to stop time here. I preferred to use a “time-extended” approach to intensify the energy that was exploding before me.

Sidi Bou Said, twelve miles north of Tunis, is a whitewashed village featuring blue windows and doors and many tourist shops. I left my tour group for a moment and wandered up the street to an intersection. I saw a bolt of light on the stone street that acted as a pointer. I also heard the repeated thumps of a ball being bounced and kicked and raised my camera just as this boy came into view. He was kicking the ball off his knee, again and again. I made a number of images, but this moment contains the most tension in the negative space between the knee and ball. He throws his arm back, rises on one toe, and propels the ball forward. The setting adds a sense of place and the light on the street points directly at him. It is very much Sidi Bou Said. And it is also a special moment in time. There are no maybes or almosts here. I simply found the exact moment I wanted to preserve.

Autumn brings the rutting season to Yellowstone’s elk. Males attempt to corral harems of cows, battle other elk for dominance, and mate whenever they can. In this image, a huge male brings all of his energy to the task – and I may well have caught the very moment in time that a new life begins. The male is moving so quickly that he is blurred at 1/80th of a second, lending even more energy and urgency to the moment. The cow seems resigned, and once mating begins, she never moved. This herd had taken over the lawns in the center of the village of Mammoth Hot Springs. Young elk are grazing in the background of this image. I made this image a few yards from our hotel. Rangers made us keep our distance for our own safety. As a result, I used a long 280mm telephoto focal length for this shot.

50,000 years ago, a meteor slammed into the desert not far from Winslow, Arizona. Tourists visiting it crater via the now abandoned Route 66 would often stop at this trading post, built in 1938. Still in business, it has the world's largest dream-catcher looming high over the speeding traffic on Interstate 40. A pair of special Route 66 flags commemorating its route from Chicago to Los Angles flanks the dream catcher. The wind roars across the open desert here with such ferocity that these flags are soon reduced to tatters. I wanted to get them to stand straight out against the rich clouds in the background. I made this image at 1/500th of a second, insuring that the flags would be frozen in mid flight.

Like two ships that pass in the night, these pedestrians slip past each other, yet they offer no acknowledgments whatsoever. Not even a nod. And nobody else was in sight to spoil this moment. I have stopped time to take normal behavior out of context and make it incongruous. I was riding in a car at the time, and we were stopped for a traffic light. I could see both of these people walking towards each other. I knew I had enough time to wait for them to get within less than a foot of each other – traffic lights in China often have a countdown feature. As you can see, I made this image with plenty of time to spare – it would be eighteen seconds before we had to get moving again. Using a shutter speed of 1/400th of a second, I rolled down the window and was able to stop each of these people in their tracks, their feet only inches apart.

By standing behind this waterfall at Zion's Lower Emerald Pool, I was able to portray the flow of water flying past my camera in an extended form. They appear here as a curtain of speeding droplets. I used a shutter speed of 1/125th of a second to achieve this effect. The image required more than a rain of water to make it express meaning. I include a diagonal branch for context. It makes the waterfall droplets appear to moving even faster.

At first glance, this photograph reminds me of a rainstorm battering a mountain valley. But it’s not. This is the impact point of the Big Slap, the highest waterfall in Plitvice National Park. The Plitvica River plunges 250 feet over a cliff, and this is where it lands. The amount of water may vary by season, but it always makes a big splash when it strikes bottom. I was able to get fairly close to this point, needing only about 100mm of telephoto reach to fill my frame. I used a medium shutter speed of 1/250th of a second to extend each drop of water into a streak of flying liquid. The grasses bend under the weight of the deluge, while the huge rocks become miniature waterfalls in themselves. This image harnesses a moment in time expressing the fury and force of nature in all of its energy.

A Vientiane commuter roars past a display of umbrellas on the city's Fa Ngum, a road that runs along the Mekong River. I was able to blur the cyclist even at the very fast shutter speed of 1/500th of a second, because of the angle at which I made the picture. When a subject is moving very fast at right angles to the camera it will show blur in some way at even very fast shutter speeds. (Slower shutter speeds can show even more blur, but under these conditions, the camera I was using would not allow me to go much slower than 1/250th of a second, which probably would not have added a significant amount of additional blur to heighten the illusion of speed.) The key to the motion expressed in this image is the contrast in definition between the sharp umbrellas and blurred cyclist. I was fortunate that she was wearing a loose jacket that was blowing behind her, and that she picked up her hand to keep her hair out of her face at the moment of exposure. Both bring a sense of additional movement to this image, as does the flow of pattern in the two umbrellas behind the motorbike.

Surrounded by offerings that she and others have carried to this temple, a woman bows again and again at the conclusion of her prayers. The room was dark, which mean using a very slow shutter speed, in this case 1/6th of a second. A tripod is out of the question – as part of a tour group, I am moving and shooting at a pace that simply will not allow such time-consuming tools. I never use a flash either. I find it intrusive, harsh, and unnatural looking. I did not increase the ISO because I did not feel it was necessary. Given the self-imposed limitations of my decisions, I still must try to make the most stable images I can with hand held exposures. My Panasonic FZ-20 has image stabilization, which gives me the same kind of stabilization here that I could expect if I was shooting at 1/25th of a second. My goal is to keep the surroundings sharp, yet also express the devotion of this woman by blurring her as she bows deeply, again and again. I achieved this goal in this image – the woman seems to flow through space as she moves her body back and forth, yet the flowers, candles, tiles, and even her purse on the floor next to her remain sharp. To do this, I cradled the camera in my palm and gently applied pressure to the shutter button. I never pushed it, simply squeezed it.

While driving through the Sierras in a pouring rain we saw this soaked Great Pyrenees protecting his flock of sheep. Using a 432mm telephoto lens from the open window of our parked car, I photographed this sheep dog as it stared back at me through the sagebrush. None of the sheep even knew I was there. But this dog did. The key to the shot is the dog’s expression and the fact that none of the sheep are looking my way. Only the dog sees me, and it never let me out of its sight. It was doing its job, and using my camera to capture this particular moment in time, I was able to do mine.

I used a slow exposure, less than 1/15th of a second, to shoot these people waiting for a bus in front of an elegant illuminated advertisement. Since these people were travelers, I wanted to use an extended moment in time to express a feeling of transition and movement. The incongruity of the large scale woman in the ad contrasted against the smaller commuters was also fascinating. I had no idea that I would also pick up the red reflection in the glass over the ad – it provides a curtain lifting on a drama. The two men in this picture are faceless because they moved while the shutter was open – another bonus for me. The blurred faces of those men only add to this mysterious flow of travelers crossing paths on a Shanghai evening.

Only a few minutes before I made the preceding photograph, I photographed a pair of women watching the never-ending march of the prayer-wheel spinners through the Jokhang Temple. I used a slower shutter speed for this shot, about 1/15th of a second, to blur the wheels, a pilgrim passing through the frame, and the hand of one of the watching women. The purpose of this blur is to increase the tempo of the picture, making things feel as if they are spinning, moving, and even watching ever more quickly.

Watching his mother quickly pack up a bag of Yak meat, this butcher's son is already learning his future trade. I used 1/40th of second to blur the hand and meat, and bring this image to life.

Days at sea on a cruise ship may be heaven for some, but frustrating for a photographer with nothing to shoot. Yet I quickly realized that expressive images could be found anywhere, even in the middle of an ocean. Gazing out to sea from the stern of the Marco Polo, I noticed that the waves made by ship’s own engines created rhythms and patterns of extraordinary beauty and turmoil. I spent over an hour shooting hundreds of digital images of those waves, trying to find the one instant in time when everything in the picture would coalesce into a marine tapestry of cohesive fury and exquisite beauty. And finally I did. After spending a half hour shooting with the camera held at horizon level, on impulse I tilted the frame, using the wake of the ship as a diagonal organizing force. Fascinated by the moving water cascading both above and below this line, I tried to time my shots to capture the most expressive water patterns both above and below this line. This is the instant in time that worked the best. At the top, streams of white water crackle in the green sea like static energy. At the lower part of the image, multiple mini-wakes rush below a series of feathery trails. A dark blue sea recedes in the distance, still white with froth, but no longer as agitated as the wake itself. This is one of those pictures where the photographer does not control much of what is captured. The movement of the sea, changing instant by instant, will determine the outcome. All I needed to do was to organize the overall structure of the image, and then just keep shooting the moving water until I found, completely by chance, the moment when everything came together.

The narrow streets of the Netherland's largest city are filled with pedestrians -- surging crowds crackling with energy. I wanted to make a picture that would best represent that energy. I put it together as I would a sandwich -- the couple in the left foreground have just come from the nearby Van Gogh Museum and are waiting for a tram that is slowly making its way towards them. The tram appears in the right background -- the curve of its track will carry it right to them. I needed something to happen in the middle zone of my sandwich to provide the "meat" -- something that would capture the eye and make my point about energy. Fortune smiled upon me as a woman pushed a stroller into the space I had reserved just for her, kicking her heel into the air as she sailed through the crowds. The camera stopped this action and recorded what some might call a "decisive moment" -- an instant where everything fell into place to tell a story.

Rush hour in Moscow's Metro is a spectacle of speed. Crowds surge along its platforms as trains roar in and out of its stations. I wanted to express a sense of speed, and did so by once again shooting at 1/30th of a second. Unlike the previous example, where the subject is entirely blurred, in this shot I contrast a blurred train to the stationary passengers waiting for it to come to rest. By contrasting blurred to non-blurred subjects in the same picture, this moment in time provides a bit of incongruity which helps tell the story. Because it is blurred, the train appears to be moving even faster than it is. And because the passengers are sharp, they appear to be all the more patient as they wait for it to stop. I chose this particular group of passengers because of the "x marks the spot" symbol created by the straps on the back of the woman in the middle of this picture. When will this train stop for her? That's the point of this picture.

Moments after I made the previoius image, the Samba band resumed its march up and down the aisles of Montevideo's Old Town Market, a huge shed crowded with large restaurants and bars. The noise was deafening, as hundreds of people clapped and sang in time to the beat of the drums and blare of the brass. I wanted to capture contrasting responses, and at one restaurant I struck gold. The light was low, and so was my shutter speed, down to a slow 1/20th of a second. Without using tripod or flash, I was able to blur the women seated in front, contrasting their spontaneous clapping and singing to the more sedate fellows behind them. The camera's ability to both extend and freeze this moment in time helps me tell my story -- some like to sing and clap, others don't.

A bull elephant, recently imported to Addo from Kruger National Park, claims his spot at a water hole with a gentle shove. When I shoot wildlife, I am interested more in how animals interact with each other and with the landscape than I am in merely describing their appearance. I trust my camera's ability to capture the moment of interaction, even when it takes place at a considerable distance. With telephoto converters and the ability to crop the image as needed, I am able to reach out across both space and time to tell the story I want to tell.

Dancing is all about motion and interaction. Both are expressed in this photograph I made of a performance at an Argentine Gaucho Ranch outside Buenos Aires. I do not use flash in my photography out of courtesy to the performers and because I want my colors to be as natural as possible. I wanted to incorporate the stage lighting into the picture because that, too, was integral to the performance. I selected 1/40th of a second -- a shutter speed slow enough to blur this particular kind of dancing, but fast enough to offer some detail for context. I included the singer at left who was accompanying the dancers, as well as some members of the audience in the background. Above all, I wanted to express the flow of the dance, and the way the dancers worked with each other. I took many photographs of this dance, but this was the moment that said everything I wanted to say about it.