Last August Daniel J. Cox spent 21 days in the Svalbard islands in the Arctic Ocean aboard a 45-foot diesel sailboat modified for Arctic exploration, working with the conservation group Polar Bears International on a book project to document the Arctic over the next three to five years.

"We're trying to collect pictures of what it's like now—the environment, the polar bears and other wildlife—so we'll have a point of comparison in the future," Dan says. "This is for history. Things in the Arctic are changing very quickly, and there's a strong chance we may not see the Arctic in ten or 20 years as we have in the past decade. It's going fast."

For safety, Dan did most of his shooting from the boat, which at first presented a bit of a photographic challenge. "For the first time, I had to shoot almost entirely without using a tripod," Dan says. A combination of factors proved to be more than an adequate solution: the quality of D700 and D300 images possible at high ISO settings and the VR steadiness of his two main lenses, the AF-S VR Zoom-NIKKOR 70-200mm f/2.8G IF-ED and the AF-S VR Zoom-NIKKOR 200-400mm f/4G IF-ED.

Dan was able to hand hold the lenses and, as he says, "crank the ISO up to keep my shutter speeds high." How high? Well, when it comes to that, Dan is decidedly old school. "My rule of thumb for sharp pictures has been around since I started, and probably long before that: set a shutter speed equal to or greater than the focal length of the lens."

Right, it's the old "make a fraction of the focal length" guideline. "So when I was shooting with the 200-400mm lens—and on the D300, the magnification factor makes that a 600mm focal length—I knew I'd need 1/600 second as a minimum shutter speed."

Did he also factor in the effect of VR (Vibration Reduction)? "Oh, I recognize that, and I shot with the VR on, but I figured that whenever possible 1/600 second was the way to go. And that speed wasn't going to be difficult to achieve when I could set 1000 or 2000 ISO."

Because he could now confidently choose from a range of ISO settings, Dan found himself, for the first time, thinking of ISO in the same way he considered f/stops and shutter speeds. "If I was on land, and had a stable platform, I'd dial the ISO down to 400 or 200. When I got in the boat, I'd dial it up to 1000 or 1200, and when the sun came out, I'd dial it back down to 400. I was changing ISO as often as I was the aperture and shutter speed, and I'd never used ISO like that before. Sure, you want the lowest ISO you can shoot, but the high ISO shots were so good, so clean, I didn't think about it very much. It became a variable, a flexible setting, just like f/stop and shutter speed."

When I spoke with Dan he'd just completed another trip in the Arctic project, this one aboard an icebreaker in the southern Beaufort and Chukchi seas on the Alaska coast. He has mixed feelings about the work. "As difficult as it is to witness some of the changes, as a photographer I realize I'm documenting history. I know there's a natural cycle taking place, but there's additional data that we've added a huge chunk of warming trend to what's naturally going on.

"What's scary is that we've seen the changes happen so quickly—last year and this year the Arctic has been nearly ice free—that in a lot of cases we don't know what's going to happen next."

Dan's website, at www.naturalexposures.com, features an extensive archive of photos and reports on his environmental activities. Visit www.polarbearsinternational.org for information about Polar Bears International.

Daniel J. Cox has been an NPS member since 1981.