A bird photographer’s options for dealing with low light are pretty limited. There are only two options: (1) work with the low light and live with the tradeoffs, or (2) add more light.
Let’s look at the second choice first. More light generally means flash. But flash has all kinds of drawbacks. Low light pretty much means winter, which in Alaska means snow and cold temperatures. Snow – especially the kinds of flat, crystalline snow we get in Interior Alaska – operates as a mirror, reflecting all kinds of light back at the camera. The result is often highly distracting, bright speckles all over your photo. Hundred or thousands of little mirrors reflecting the light back at you. Not good.
Flash also means batteries, and as we all know most batteries don’t perform well at low temperatures. Basically, the chemistry that makes the juice comes to a halt as the chemicals in the battery freeze. Often, you get only a few shots. In the best case, you spend all of your time moving batteries between a warm inner pocket and the cold flash unit.
And flash often spooks the bird. That’s bad in two ways. You only get one shot. And you’ve altered the behavior of the bird which, for many of us, is a no-no. Winter birds in Alaska have it tough enough without being spooked, too. For WC, this is the deal breaker.
WC has tried a wool sock over the barrel of the flash lined with a handwarmer to keep the flash warm. It doesn’t work as well as theory would suggest.
One of WC’s buddies reported his strobe flash shattered when it fired off at -45° F. That hasn’t happened to WC. But the velcro fastener for WC’s flash extender has turned to little plastic fragments.
So flash is generally less that successful and sometimes potentially harmful. What about just dealing with the low light. The inescapable laws of physics limit your choices.
You can increase the aperture, letting more light through the lens. This has its limits. Really wide aperture lenses are more expensive because they involve more expensive glass. A good 300mm lens with a maximum aperture of 5.7 might cost you $200. A good 300mm f2.8 lens, letting in three times as much light, will cost you close to $7,000. Ouch. No one makes a faster 300mm telephoto lens than f2.8, because (a) you’d have to rob a bank to buy one and (b) you’d need a forklift to haul it around. So for letting in more light with a bigger aperture, you options end at a spendy f2.8.
You can increase the time the shutter is open. Longer exposure mean more light. But the problem there is that birds are hyperactive little buggers, and you need a pretty fast shutter speed if you want to avoid motion blur. The world has enough blurry photos of birds. WC has taken many of them. Longer exposures than about 1/250th will show blurring in the chest from breathing. So shutter speed is a limited solution.
You can increase the sensitivity of your camera’s sensor. Back in the old days of film, you bought “faster” film, a more sensitive emulsion. And, if you could, you processed it as if it was even faster. Film speed – sensitivity – was measured by ISO. “ISO” is too complicated to explain here, but the film speed principles were mostly carried over to the digital camera era as a measure of the sensitivity of a digital camera’s sensor. A high end digital camera can offer ISO200000 – 400000. That’s not a typo. WC’s Canon 1D-X will actually crank up to ISO204800. But as with high speed film, high speed digital ISO means a lot of noise – speckling – in the photo.
That means you can’t get good photos at ISO204800. In fact, you get pretty crappy photos. The capability does not imply the quality. But digital sensors, in-camera processors and noise reduction algorithms have made amazing advances. The Canon 1D-X performs well at ISO2000 and adequately to ISO10000. Each new generation of cameras brings improvement. But every camera has a limit; you’ll need to experiment with various ISO settings on you camera to find yours.
And you’ll find noise is worse in darker areas. In a winter photo of a bird, the bird is usually the darker area. And the lower the light, the lower the resolution. To some extent, the camera has to “guess” to fill in the missing photons.
Yes, there is noise reduction software you can apply in post-processing, and in many situations it is astonishingly effective. But it does unkind things to bird feathers, which the software algorithms seem to interpret at noise.
And that’s all of your choices. Bigger glass for a larger aperture to get more light; longer exposure to get more light; or increased sensitivity to make more use of the light you get. All have limits and drawbacks.
|Technique||Limits and Drawbacks|
|Bigger Aperture||Increasingly expensive; increasing size; can’t get larger than f2.8; shallow depth of field|
|Shutter speed||Motion blur, from the camera if hand-held, from the subject even with a tripod|
|Increased ISO||Increasing noise, especially in darker areas; increasing loss of detail|
Of course, these three considerations can be combined. A wide aperture and be combined with a fairly slow shutter speed and the highest ISO at which your camera can reliably perform. In fact, that’s your best resource, short of waiting for more light. Experiment. Learn the highest ISO at which your camera can perform without unacceptable noise. Get a feel for the shutter speed you need to freeze the movement in your shot: a still life of a fruit bowl might be different than a foraging Red-backed Vole.
Let’s look at a specific example. Here’s a Common Redpoll WC photographed last weekend, in late afternoon under heavy overcast.
This photo was taken with a 500mm telephoto cranked to its maximum aperture of f4.0. Handheld, WC didn’t dare use a shutter speed of less than 1/400. As a result, the ISO had to be pushed up to ISO20000. The wide aperture resulted in a very shallow depth of field; the eye is reasonably sharp but the tail and even the belly are blurred. There’s significant noise in the whole photo, especially noticeable in the branch and dark colors in the bird. But those are the trade offs when shooting in low light. WC’s old Olympus E-5 would have produced a speckled mess if it could operate at ISO20000, and it could not.
So, if you want to photograph in low light, especially moving critters, learn the capabilities of your camera, the demands of the shot you want to take and a little bit about the physics of light and camera sensors.
Because spring and decent light is still a long ways off.