A simple formula for taking perfectly exposed pictures of the most challenging bird subjects

Photographing white birds is a challenge. Often the bird’s image winds up looking either washed out with no detail in the white feathers or drastically under-exposed, making the bird appear gray instead of white. For many photographers, creating true-to-life pictures of white birds seems like a mythical ideal that is seldom achieved. But actually, anyone can consistently take perfectly exposed pictures of white subjects. All it takes is a basic understanding of how to use your camera’s built-in spot meter to determine the best exposure for the film you’re using.

Modern cameras are the most sophisticated ever made. Some not only measure exposure values in segmented matrixes but also recognize color values. Using these cameras in the automatic exposure mode, you can take accurately exposed pictures 95 percent of the time without touching the shutter-speed or aperture settings. But there’s the rub: for the other five percent of your picture taking—which includes white birds and other difficult subjects—a camera’s automatic-exposure mode is completely inadequate. When it comes to photographing a white bird, no light meter in existence can determine an accurate exposure—unless the photographer makes some type of exposure compensation.

American White Pelicans

Because white birds lie outside the range of a light meter’s automatic exposure capability, you should set your camera to manual exposure and use a spot-metering system. Many, and perhaps most, single-lens-reflex (SLR) cameras now have three built-in light-meter modes: matrix, center-weighted, and spot. If you set it in the matrix or center-weighted modes, the meter takes readings from different areas of the film plane and averages them together to determine the exposure. But in many cases, an average (midtone) exposure may be the last thing you want. A spot meter solves this problem by taking a reading only in a small area at the center of the frame. And when you use a long telephoto lens—the norm for most bird photography—the spot-meter-sensor area is even more closely defined.

Each camera model has its own method of indicating the proper exposure when it’s in manual exposure mode. Some use lights in the viewfinder to indicate a proper midtone exposure. Usually a small light along the right- or left-hand side of the viewfinder will turn green when you set the exposure to the correct shutter speed and aperture combination. Red lights above and below the green light indicate by how many f/stops an image is over- or under-exposed. Some have a match-needle system. Others use an analog scale. For demonstration purposes here, I will refer only to an analog scale.

Snowy Egret

In most modern cameras an analog scale appears at the bottom of the viewfinder when you select manual exposure. It usually consists of a line with a zero point at the center and plus-and-minus, 2-f/stop increment indicators on either side. The plus-and-minus indicators are usually further divided into 1/2- or 1/3-f/stop increments. The zero indicates the correct midtone exposure setting; the plus and minus marks indicate values above and below a midtone.

A spot meter allows you to measure the brightness of the light in various parts of a scene and compare them with each other (and with the midtone exposure) on the analog scale. Areas of the image that you wish to be lighter than a midtone should appear on the plus side of the zero, and areas you wish to be darker than a midtone should appear on the negative side. Using an analog scale allows you to check how many f/stops certain areas in a scene fall above and below the midtone. Where you should set your exposure depends on the latitude of your film.

Slide film is the least forgiving with a latitude of only 3 f/stops—you can successfully take a picture exposed at as much as 1 1/2 f/stops above or below a midtone. Color print film has a latitude of 5 f/stops, but black-and-white print film has the greatest latitude, providing a full 7-f/stop margin of error. Because most bird photographers use slide film, I will base my example on this.

It is important to understand that a light meter bases all exposures on midtones. A midtone is any value that reflects 18 percent of the light that falls on it. It can be red, blue, green, or any combination of these colors. The only requirement is that it reflects 18 percent of the available light.

Camera light meters are calibrated in such a way that no matter what your photographic subject is, the meter will ndicate an aperture and shutter-speed combination that will produce a midtone exposure. This is great if you’re actually photographing a midtone subject. But if your subject is lighter or darker than a midtone, you’ll get a false reading, and your picture will be either over- or under-exposed. For example, if you take a meter reading of a white subject, your camera will give you an exposure setting that will render white as a midtone—basically a gray. To reproduce a white subject accurately on film, your exposure setting must be adjusted. You have to open up the aperture (or slow down the shutter speed) to allow more light to reach the film. This will move the exposure to a proper, lighter value. How far the metered white value should be moved depends on the latitude of your film.

So how does this relate to photographing white birds? White birds are as much as 3 1/2 f/stops lighter than a midtone. Therefore when you photograph white birds with slide film—which has a latitude of 3 f/stops—you must adjust the exposure accordingly. But before adjusting the exposure, you have to determine what a midtone exposure would be for the subject you’re photographing. This is where all the mumbo jumbo about latitude and manual-exposure spot metering comes into play.

With your camera in the spot-metering mode, point your lens toward the white bird and place the spot-meter sensor on the lightest portion of the bird where you want to retain feather detail. Take a meter reading and adjust the aperture (or shutter-speed) setting so that the exposure indicator is on the zero mark of the light meter’s analog scale. If you took the picture now, using this exposure setting, you would end up with a picture of a gray bird. To get the detail you’re after in the white feathers, open up the aperture to allow more light to reach the film. The exposure indicator of the analog scale will move to the plus side as you do this.

Remember that the latitude of slide film is 3 f/stops—1 1/2 f/stops above and below a midtone. Opening the aperture 1 1/3 f/stops above the midtone or zero point on the analog scale will give you an exposure that will make the bird’s feathers white in your picture. But why increase the amount of light by only 1 1/3 f/stops if the latitude of slide film is 1 1/2 f/stops above a midtone? Because this sets the exposure at the threshold of the film’s ability to produce a white with detail. The white feathers would be white if you used an exposure setting 1 1/2 f/stops above a midtone, but the feather detail would be lost.

It’s really simple: spot meter the lightest feather of the white bird, and then set the exposure to 1 1/3 f/stops above the midtone mark on the analog scale. You now have the perfect exposure for a white bird, capturing complete detail in its feathers. It works on sunny days, cloudy days, and rainy days—every time. If you’ve made the move from film to a digital camera, no sweat—exposing a digital flash card is just like shooting slide film. This method will render a perfect exposure in a digital format.

What if your camera doesn’t have a spot meter? Just choose any midtone value in the same light as the white bird you want to photograph. Set the shutter-speed and aperture combination that will give you the best exposure for that midtone, then close the aperture by 1 1/3 f/stops. This moves the midtone to a darker value, but it also brings the white feathers of the bird into the latitude range of your film, giving you a perfect exposure.

That’s it, pure and simple: the myth is debunked, the truth about photographing white birds is exposed. It’s time to get out and start taking great images of white birds, confident that every exposure will be perfect.