When I first photographed bears at Katmai, I was using a Nikon 8008 and shooting Fujichrome Velvia 50 and Provia 100. I’d bite my nails, hoping the weather would be nice. If we had clouds and low light, my ratio of usable shots would be embarrassingly low. Photographing a 1,000-pound brown bear running in murky low light at ISO 100 was an Olympian feat. Even with wide-open apertures, my shutter speeds were really slow. I could push (increase the ISO) my 100-speed film to 200, but this only added one stop of light. So instead of shooting at 1?30 sec., I could shoot at 1?60 sec., resulting in grainy, blurry shots. I like to think of this part of my wildlife photography career as my “abstract period.” I produced a lot of abstract motion-blur images, but few tack-sharp shots.
How times have changed. Today’s cameras are technological wonders, and all photographers benefit using these advanced features. The default ISO for many cameras today is ISO 200, and pushing this number higher is the norm, not the exception. I use a Nikon D3 and regularly shoot at ISO 800, 1600 and even 3200, five stops faster than ISO 100. So instead of photographing those bears at 1?30 sec. in low light, I can shoot at 1?1000 sec. Bring on the charging grizzly!
There are lots of ways to take advantage of the high-ISO performance of today’s cameras. But before we explore high-ISO techniques, let’s look at how camera sensors work and what affects their ISO performance.
Camera sensors consist of an array of photosites where light is captured. Sensors capture light (photons) and convert this into an electrical charge that’s eventually converted to a digital value by the analog-to-digital converter. The camera processes this digital value into the final image. Most camera sensors today are either CCD or CMOS. The big concern with high ISO and long exposures is noise. Two kinds of noise cause problems for photographers. Luminance noise appears as gray (varies from white to black) speckles that pop up in your image, most easily seen in the solid colors and dark areas of your shot. Luminance noise in digital shots is the equivalent of grain in film. Color noise appears as colored specks that show up randomly in your image.
What’s important to the photographer is the sensor size and the camera software used to process the image. The rule of thumb is the larger the sensor size, the better the camera will perform at high ISO and long shutter speeds. For a set amount of photosites, larger sensors will have a better signal-to-noise ratio, resulting in less noise.
Another aspect that affects ISO performance is the camera software. Camera companies are continually improving their image-processing software to produce cleaner digital images with less noise. With sensor size being constant, if I compare an image shot from one of my early digital cameras to one I recently bought, the new camera produces dramatically less noise. The good news for photographers is that sensors and software continue to improve with each new camera release, so expect even less noise in the future. If you really want to see how your camera’s sensor stacks up, take a look at DxO Labs’ analysis of raw image quality (www.dxomark.com).
The ISO Advantage
I remember talking to Dave Black (www.daveblackphotography.com) when the Nikon D3 first came out. This was Nikon’s first large-sensor (FX-format) camera. He told me this camera would change the way I photographed and open up new possibilities in low-light photography. Dave is an incredible photographer, and this was a huge statement coming from him. ”Change the way I photographed…” He was right.
When I started out in photography, aperture and shutter speed were used to control your exposure. ISO was a constant, except on rare occasions when you pushed film one or two stops. Photographers just didn’t think about changing ISO because the side effect of increased grain quickly degraded image quality.
But with today’s cameras, I’ve had to adopt new shooting habits. ISO is equally as important as shutter speed and aperture in controlling the light. Some cameras offer an “auto ISO” function that allows you to maintain a constant aperture or shutter speed shooting in variable light. The camera simply changes the ISO to maintain your shutter speed or aperture. ISO performance is so good that it’s no longer taboo to change it. So dial up your ISO and try one of the following techniques to experience the ISO Advantage.
1. Freeze The Action. One of the obvious ways to use high ISO is to freeze the action, even in very low light. While photographing bears in Katmai, I really wanted to freeze their “salmon-strafing runs.” The bears would plow down the middle of a stream chasing salmon, splashing water and literally chasing fish up onto the rocky beach. To capture this scene, especially freezing the water droplets, I needed a fast shutter speed, 1?1000 sec. or faster. Even though we had decent light, I still dialed my ISO up to 800 to get fast shutter speeds.
2. Leave The Tripod At Home. Well, not exactly. Tripods are a great tool and result in tack-sharp images (I use one whenever I can). But what if you’re in a small boat, bouncing in the waves, trying to photograph a black oystercatcher. You can’t use a tripod because your shooting platform is too wobbly. Simply dial up your ISO to increase your shutter speed to a level at which you can create sharp images. Another benefit is that you can handhold long telephoto lenses, especially if you have image stabilization. Last summer in Alaska, I was photographing bald eagles from a skiff in the ocean. Almost everyone in our boat was handholding a 400mm or 500mm ƒ/4 lens and using high ISO to shoot fast. The resulting images were incredible—tack-sharp bald eagles soaring against the snowy peaks. Handholding 400mm lenses? Amazing!
3. Shoot At Night. Just when you thought your shooting day was over, now you can shoot all night long. Night photography is popular, especially light painting. No doubt this is due, in part, to improved ISO performance and instant feedback on your LCD. Long exposures used in night photography was the one advantage film had on digital until the improved sensors arrived. I shot star trails recently, a one-hour exposure, and had minimal noise, very similar to results I get when using film. Even better, now I can dial up my ISO to 3200 and shoot the Milky Way and stars at short shutter speeds with stunning results. This wasn’t a reasonable option a few years ago; ISO 3200 had way too much noise. One important camera feature to turn on is “long exposure noise reduction.” This will reduce noise in long exposures greatly (although not all cameras have this option).
4. Capture A Live Performance. Most of us want to photograph a live performance at one time or another. Maybe it’s a concert, a high-school basketball game or a birthday indoors at home. Flash gives us one option of tackling these low-light situations, but sometimes you miss a candid moment waiting for your flash to recycle. Some venues don’t allow flash photography. Once again, the ISO Advantage comes to the rescue. Dial up your ISO, and shoot away. I attended a tango performance in Buenos Aires last year, and flash photography wasn’t allowed. The scene was very dark, so I dialed up my ISO to 6400 and got the shot.
5. Give Your Flash A Break. TTL flash photography has advanced as much as sensors have improved in the last few years. Many flashes work wirelessly, and output can be controlled by a transmitter on the camera. Numerous light modifiers and accessories have cropped up, allowing even beginning photographers to create dramatic portraits. All you need is one or two TTL flashes. A downside to using TTL flash is that shooting full-power bursts results in long recycling times, and you can go through AA batteries quickly. One solution for this problem is increasing your ISO a few stops, making your camera more sensitive to light and requiring less flash output to get your shot. Imagine if I’m shooting a scene at ISO 200 using ƒ/11. If I set my ISO to 800, two stops more sensitive to light, I can shoot at ƒ/11, but use two stops less flash power to get the same results.
6. Increase Depth Of Field. I mentioned earlier how increasing ISO allows use of faster shutter speeds to freeze the action. But what about aperture in this equation? Since aperture controls depth of field in an image, now you can capture more depth of field in low-light situations and also when using long telephoto lenses.
Photographing sea otters recently, I discovered a perfect use of the ISO Advantage. We found a patch of kelp in which the otters had anchored themselves to keep from floating away with the strong tides. Not just a few otters, but more than 100 were resting in this kelp bed. I focused on an otter about 30 feet away with my 400mm lens and got a nice head shot. But I realized there were numerous other otters in the background, all out of focus because I was shooting at ƒ/4 at ISO 200. So I dialed up my ISO to 1600, gaining three stops, and shot at ƒ/11. The otters in the background were sharper.
7. Shoot From The Car. I shoot a lot of travel photography in some remote locations. I often spend hours, sometimes days, riding in vans and buses to get to the location. Even more frustrating than the long rides are some of the stunning images I watch pass by. Before better ISO/sensor performance, I’d miss these shots, but not anymore. I frequently shoot from the van window on road trips. In Mongolia last summer, we spent many hours in vans driving to different parts of the country. Not wanting to miss a shot, I dialed my ISO up to 800 and got some classic images of a lone horseman riding across the rolling green hills—images I would have missed in the past.
Dealing With Noise
Every camera (and sensor) performs differently in handling noise. Some cameras may have noise at ISO 400, while others don’t produce much noise until ISO 3200. Remember, it’s better to get the shot and deal with noise later than not get the shot at all. How do you reduce noise after the shot? Both Lightroom and Photoshop (and other popular imaging applications) now have tools to deal with noise.
In Lightroom, select your image and go to the Develop module. Scroll down on the right side and click on the Detail tab to list the options here. Below the Sharpening tool are the noise-reduction sliders. Choose which type of noise you need to reduce, and drag that slider to the right. I normally find I need to reduce luminance noise, so I pull the Luminance slider way to the right. Make sure you’re viewing your image at 100% on a high-noise area so you can see the effects. Reducing noise will soften the image, so I normally add a little sharpening after reducing noise.
In Photoshop CS4, go to the Camera Raw window and select the Detail icon (two triangles). Make sure to enlarge your image to 100% to see your progress. As in Lightroom, use either the Luminance or Color Noise slider to reduce the type of noise you have in your image.
For more control and impressive results, try a third-party plug-in to deal with noise. Most of these companies offer a free trial of their software so you can choose the one that works best for you. A few popular ones are Noise Ninja (www.picturecode.com), Noiseware Professional (www.imagenomic.com) and Dfine 2 (www.niksoftware.com).
The next time you find yourself in low light, don’t put your camera away. Just use the ISO Advantage and get the shot.
Tom Bol is a freelance editorial and commercial photographer based in Colorado. Visit www.tombolphoto.com.