Beneath the stars

Gary Hart Photography: Bristlecone Star Trails, Schulman Grove, White Mountains, California

Bristlecone Star Trails, Schulman Grove, White Mountains, California
Canon 1Ds Mark II
36mm
22 minutes
F/4
ISO 200

October 2012

I lead photo workshops in lots of beautiful, exotic places, but I particularly look forward to the Eastern Sierra workshop for the variety we get to photograph. Mt. Whitney and the Alabama Hills, Mono Lake and Yosemite’s Tuolumne Meadows, lots of fall color in the mountains west of Bishop and Lone Pine, and the ancient bristlecones in the White Mountains, east of Bishop.

It’s the opportunities to photograph the mountains surrounding Bishop that most stimulate my creative juices. Each fall the small lakes, sparkling streams, and steep canyons west of Bishop are lined with aspen decked out in their vivid autumn yellow. Contrast that with the arid White Mountains east of Bishop, where virtually nothing thrives except the amazing bristlecone pines. The bristlecones are among the oldest living things on Earth, and they look it. The character they’ve earned by enduring up to 5,000 years of cold, wind, thin air, and water deprivation makes them ideal photographic subjects. There’s wonderful texture in the bristlecone’s twisting trunk and branches, but sometimes I like to turn off the texture with a silhouette that emphasizes the gnarled shape.

The bristlecone here clung to a steep hillside in the Schulman Grove of the Ancient Bristlecone Pine Forest. I was there with three friends on a moonless, late September night in 2007. They wanted to light-paint the tree, but I wanted something that just emphasized the tree’s shape against the stars. With our shots set up, I delayed my exposure for a few seconds while they hit the tree with a bright flashlight, clicking as soon the world went dark. Then we just sat and waited in the chilly air, enjoying the sky, laughing quite a bit, but sometimes just appreciating a silence that’s impossible to duplicate anywhere in our “normal” (flatland) lives.

As we waited we scanned the sky, thick with stars, for a rogue airplane that might threaten to soil our frames. Only one appeared, and when it did I held my hat in front of my lens, holding it there for about fifteen seconds, until the plane moved on. (If you look closely you can actually see a small gap in the same place on the otherwise continuous star trails.)

We had long exposure noise reduction turned on, so we couldn’t see our results until our cameras finished their processing. The pictures didn’t pop up on to our LCDs until we were halfway back to Bishop, but I was driving and had to wait until we got back to town. We pulled into Bishop, tired and hungry, so late that we had a hard time finding anything open, but everyone was so pleased with their images that even Denny’s tasted good.

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Riding the celestial carousel

Gary Hart Photography: Star Trails, Desert View, Grand Canyon

Star Trails, Desert View, Grand Canyon
Canon EOS-5D Mark III
28 mm
31 minutes
F/4
ISO 400

It’s pretty difficult to feel important while reclined beneath an infinite ocean of stars, peering into the depths of the Grand Canyon. Below you unfolds a cross-section of Earth’s last two billion years, chronological layers of landscape sliced by gravity’s inexorable tug on the Colorado River; overhead is a snapshot of the galaxy’s (perceived) pinwheel about the axis of our planet’s rotation.

From our narrow perspective, at any given time, the Universe appears fixed. But observe the night sky for a few hours and you soon realize more is at play. Those points of light overhead all follow the same east to west arc across the celestial sphere, ultimately disappearing beneath the horizon (or behind the glow of daylight). Most return to the same place twenty-four hours later, but a few shift relative to the stellar background. For millennia explaining these wanderers while maintaining our position at the center of the Universe required convoluted solutions that defied scientific scrutiny. Then Copernicus, in one elegantly simple paradigm shift, removed Earth from the center of the universe and set us spinning about the Sun, pouring the foundation for humankind’s understanding of our place in the Universe. The humbling truth is that we inhabit a small planet, orbiting an ordinary star, on the outskirts of an average galaxy.

Thanks to Copernicus, Galileo, and others who followed, we now take for granted that Earth revolves about the sun, secured by gravity’s invisible string. And while it appears that our star-scape spins above our heads, it’s actually you and me and our seven billion Earth-bound neighbors who are spinning. (It helps to imagine Earth skewered through our north and south poles and spinning around a pole of infinite length.)

For those of us in the Northern Hemisphere, the centerpiece of this nightly show is the North Star—Polaris. Conveniently (and coincidentally) positioned less than one degree from the northern axis of our spin, Polaris is a white-hot ball of ionized gas six times the size of our Sun. (It’s so distant that when the light we see tonight left Polaris’ surface, Copernicus was less than a generation dead and Galileo was a teenager.)

Locked into our terrestrial frame of reference, distracted by the problems of life, we stay generally oblivious to the celestial dance overhead. But I can think of no better way to get some perspective on our place in the universe than to look up on a moonless night, far from city lights. On these nights our planet’s rotation, too slow to be perceived at any given instant, is captured beautifully by a fixed, Earth-bound camera that rotates with us, blending multiple, sequential instants into a single frame. This long exposure stretches each star, a discrete point to our eye, into continuous arc of light, the length of which is determined by the duration of the shutter’s opening—one degree of arc for every four minutes of exposure.

From our perspective the northern sky appears to circle the north celestial pole (occupied by Polaris). Images that include celestial north are etched with concentric arcs—if there were some way to continue the exposure for twenty-four hours (say in the dead of winter at the North Pole), our image would show Polaris like a brilliant gem ringed by full, perfectly symmetrical circles. To a camera centered on the celestial equator (the halfway point between the north and south axes of rotation), a long exposure reveals divergent arc, with the stars north of the celestial equator bending around the north celestial pole and stars south of the celestial equator bending the other direction, around the south celestial pole.

A few words about this image

The above image was captured during my 2012 monsoon trip to the Grand Canyon. Don Smith and I had spent the day chasing (and dodging) lightning, but because we didn’t feel we’d taken enough risks, we thought it might be a good idea to stumble about with the mountain lions, in pitch dark, on the rim of a one mile deep chasm.

While photographing late afternoon and sunset from Desert View, we scouted potential starlight locations in daylight, and returned to the car to eat sandwiches and wait for darkness. And dark it was. Dark enough that I couldn’t really see the canyon’s edge, which was about two feet from my tripod.

Also dark enough that focus was a real challenge. Using my fastest lens, a 28mm Zeiss f2, I found the brightest star and centered it in my viewfinder, then switched to live-view, magnified the view 10 times, and manually focused on the star, which was faintly visible near the center of my LCD. (My Zeiss doesn’t have autofocus—if you try this with an autofocus lens, don’t forget to switch it to manual focus before shooting.)

With focus set, I tried some test frames to get the exposure and composition. It was too dark to compose the canyon through my viewfinder, so I bumped my ISO to 24600 and took a series of wide open (f2), 30-second exposures, tweaking the composition after each until I got it right. Knowing that increasing my exposure duration from 30-seconds to 30-minutes would add six stops of light, I subtracted six ISO stops (25600 to 400). (I’m still learning this lens’s capabilities—next time I’ll stay at f2 and go all the way down to ISO 100 for a 30-minute exposure.)

Waiting for our exposures to complete, Don and I just kicked back and admired the night sky. We saw several meteors cut the black, and several satellites drift by. The city of Page, sixty-five miles north, was a faint glow to our eyes (but much brighter to the camera). Sporadic lightning flashes illuminated clouds to the northwest, well beyond the North Rim and probably as far away as Utah. And the Milky Way, the community of billions of gravitationally connected stars to which our Sun belongs, spread from horizon to horizon.

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Photographic reality: Expand time

Cascading Ferns, Russian Gulch Fall, Mendocino
Canon EOS-5D Mark III
81 mm
.6 seconds
F/11
ISO 400

“Photography’s gift isn’t the ability to reproduce your reality, it’s the ability to expand it.”

(The fifth installment of my series on photographic reality.)

There’s probably no better example of the difference between a camera’s reality and yours than the way we handle motion. In my previous post I compared the camera’s ability to accumulate light to the serial, real-time processing of seamless instants we humans do. In a static world, given the right exposure a photographic image can be rendered fairly literally (missing dimension notwithstanding). But photograph a world in motion and wonderful things start to happen.

A slow shutter speed allows a sensor to record the position of everything it “sees” during the exposure, expanding one frame into a recreation of every instant of its capture. When the capture includes objects in motion, the result a scene very different from the human experience: Rushing water smoothes to white, wind-whipped flowers blur to color, and Earth’s rotation renders stars as parallel streaks of light.

Blurred water

Labeled as cliché and unnatural by people who don’t understand photography, blurred water gets a bum rap. The cliché part ignores the fact that most rapidly moving water photographed in the best light (shade or overcast) is virtually impossible to not to blur. The “unnatural” label just cracks me up—when asked, detractors reply that freezing the motion (the only other option) would be more natural, to which I reply (usually to myself only, tongue firmly clamped between teeth), how many times have you seen water drops frozen in midair? The truth is, the camera and human eye handle motion differently, and photographers need to accept and appreciate it. Once you can accept that blurring water is often the best way to imply motion in a static medium, the fun begins.

First you need to understand that you can’t just blur every moving river, stream, or wave. Motion blur requires a slow shutter speed, impossible with water in full sunlight without a neutral density filter to cut the light. So you need to start by finding moving water darkened by overcast or shade (any sunlight in the frame at all will overexpose and likely ruin the image). Whitewater is best; if you find yourself photographing whitewater in shade or overcast, the question isn’t how to blur, it’s how much?

Unfortunately there’s no magic shutter speed for motion blur. The amount of blur you get depends on the speed of the water, how close you are to the water, how much you’re zoomed, and the angle of your capture relative to the direction of motion (and maybe some other things I’ve overlooked). And while there isn’t a ideal amount of blur, I find that there’s sweet spot (that changes with all the variables above) between very slight blur that’s not quite enough and just appears scratchy, and extreme blur that’s pure white. In some tight compositions of extremely fast water you get beautiful slight blur at 1/1o second; with wider compositions and/or slower water, the same amount of blur requires 3/4 second or longer. And achieving noticeable blur in a wide capture of a distant waterfall may require several seconds of exposure. My advice is to bracket your shutter speeds, varying your ISO and/or f-stop (take care that you don’t choose an f-stop that compromises your depth of field)—you’ll find the more you do it, the more you’ll get a sense for what works.

In the image of Russian Gulch Fall near Mendocino (at the top of the post), I arrived early enough to allow a full two hours to work the scene before sunlight blighted the forest floor. And work it I did, starting wide and trending tighter as I became more familiar with the scene. The dense forest dark didn’t allow a fast enough shutter speed for effective slight blur without severely compromising ISO and aperture (depth of field), so I just went with the extreme blur. Even though the air seemed perfectly still, I was a little concerned about slight wind motion in the ferns, so I bumped to ISO 400 and f11 (at 80 mm, f11 gave me about a 15 foot range of front-to-back sharpness–just enough). This resulted in a one second exposure that caused extreme blur (I call it extreme because I didn’t notice much difference between one second and five seconds) that, as it turned out, made the delicate strands of water quite lovely.

One other often overlook component of a forest water scene is a polarizer: I wouldn’t even attempt a scene like this without the glare reducing benefit of a polarizer. (And a polarizer has the added bonus of reducing the light by a couple of stops.)

Bristlecone Star Trails, White Mountains, California

Star trails

Star trails—parallel streaks of light caused by Earth’s rotation during a long exposure–are an extreme example of the same motion effect that blurs water. I find that moonless nights work best for star trails—a moonlit sky is usually too washed out for effective star trail photography, while the limited light of a moonless night maximizes the motion by allowing even the dimmest stars to shine through.

On a moonless night, a large aperture and high ISO can record enough light to allow a relatively fast 30-second shutter speed that records stars as near pinpoints of light, but doesn’t allow enough light to fully eliminate the foreground. On the other hand, a slower shutter speed that accumulates enough light to reveal the foreground also results in streaking stars—star trails. An added advantage of star trail photography is that the exposures are long enough to enable a smaller aperture (more DOF and better image quality) and lower ISO (less noise).

Some people have great success combining a series short-exposure frames to create a single star trail image, but all of my images are single-click capture (that’s just me, I have no problem with those who choose to blend multiple captures) using a trial and error approach I’ve worked out over the years. I start by taking a test (throw-away) exposure at my camera’s highest ISO and lens’s widest aperture, then tweaking the exposure and repeating until I get it right. I’ve also found that in the near total darkness of a moonless night, these test exposures are the best way to ensure my composition and focus are okay. Once I have my exposure, composition, and focus right (it usually takes two or three images), I figure out how many stops of light my desired shutter speed (usually around thirty minutes) adds to my successful test exposure, then subtract an equal amount of light through a combination of aperture and ISO reductions. (I’ll try to post a more thorough tutorial on my approach to star trails soon.)

I photographed the above bristlecone pine against backdrop of streaking stars with three friends who were light painting the tree—sweeping the beam of a bright flashlight across the trunk and branches for the first few seconds of exposure to illuminate the tree’s weathered wood enough for their cameras to capture the exquisite detail. But all my images use only natural light, so I opted for a silhouette, positioning myself as low as I could get to juxtapose as much of the tree against the sky as possible.  I started my exposure as soon as the others’ light painting ended (no more than ten seconds), and for the next twenty-two minutes the four of us reclined there at nearly 11,000 feet, watching the sky and waiting for the exposure to complete. We talked and laughed some, but mostly we just appreciated a sky dense with stars and silence so complete (and foreign) that it almost hurt my ears. We were well down the road toward our hotel in Bishop before my camera finished its processing, and it wasn’t until I was able to view the image on my laptop that I knew I’d had a success.

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