In this article, I’ll give you an idea of how I handle exposure control, in the context of nature and wildlife shooting. There’s no one correct way to assess and set exposure, of course, but I’ll explain what I’ve found works for me, and the reasons for it. I’m targeting this article at serious photo enthusiasts, and will assume you already understand fundamentals of camera operation, metering, and so on. Hopefully, one or more points will resonate with you, and help you get even better results in your photography!
Determine the Optimum Exposure
An excellent exposure will produce outstanding color, preserve highlight detail, and reduce noise, especially in the shadows. How do you know when the exposure is optimum? Many photographers assume that viewing the image on the camera’s LCD allows them to accurately judge the exposure. The LCD monitor brightness greatly influences how the image appears, and is adjustable with an in-camera control called LCD Brightness. It can be set to Auto to provide optimal viewing for varying ambient light levels, or Manual to one of several brightness levels. Monitor brightness helps you view the image, but does not indicate that the optimum exposure is obtained. For instance, if an image looks too bright (overexposed) on the LCD, the monitor brightness can be darkened to make it appear much better. Conversely, if the image appears dark, the monitor can be made brighter to make the image look much better for viewing. In either case, though, the image’s appearance on the LCD monitor alone does not mean the exposure is ideal. Instead, use the camera’s histogram display or highlight alert to arrive at a suitable exposure.
Histogram or Highlight Alert
There are two in-camera tools I rely on constantly for exposure control, and many other experienced wildlife photographers do as well. For years I used the histogram to make a worthwhile exposure. I shoot RAW Canon files, but there is nothing wrong with shooting using the in-camera processed JPEG images if you wish. I favor the greater processing capability that is offered by RAW files with Canon’s free Digital Photo Professional (DPP) version 4 software.
Exposing to the right (ETTR) is a well-known strategy for preserving highlight detail, minimizing shadow noise, and collecting the largest amount of data that is useful when processing the image. It’s especially effective when you know some parts of the image, even if it’s only small highlights or a tiny part of the scene, should reproduce as pure white tones with a hint of detail. Simply set the exposure to make the right-most data on the histogram almost touch the right wall of the histogram graph if shooting JPEGs, and let it actually touch the right wall a little if shooting RAW files. This method works well, but in many scenes the right-most data representing the brightest tones in the image are few, and so this small area on the histogram is difficult to see. Nevertheless, monitoring the histogram’s right-most data and where it appears at the right wall of the histogram is an excellent method for monitoring the exposure.
Another tool I use to verify exposure of the bright highlight areas is the Highlight Alert, during image playback on the LCD monitor. No matter how I am metering – Manual exposure or any auto-exposure mode — I set the exposure to produce a few “blinkies” in the highlights when shooting RAW. If shooting JPEGs, set the exposure to produce the first “blinkies,” and then darken the exposure by 1/3-stop.
Let me clarify why I work a little differently with the Highlight Alert, depending on whether I’m shooting RAW or JPEG files. The reason you can view a RAW image on the camera’s LCD is because all RAW files have a small JPEG contained in the file. From this camera-produced JPEG image, the histogram and highlight alert are derived. However, RAW files contain far more data than a JPEG, so the camera-produced JPEG always indicates overexposure before the RAW data is truly overexposed. Accordingly, if I am shooting RAW, I’ll let a few blinking highlights exist when I check those exposures.
First, Let’s Make a Few Settings to Your Canon Camera
1. Enable the Highlight Alert
The camera’s default settings have the highlight alert disabled. Look in the camera’s menu (on most Canon EOS DSLRs, it’ll be in the blue Playback Menu area) and turn the highlight alert to Enable. If the camera “thinks” certain areas of the image are overexposed, when you view the image on the camera’s LCD, these areas flash off and on. I and most other photographers call them “blinkies.” The highlight alert makes exposure incredibly easy to determine because the flashing highlights are obvious, whereas a small amount of highlight data on the right side of the histogram often is difficult to see.
2. Reverse the Dials
Most Canon cameras let you reverse the dial direction for adding light with the shutter speed and aperture dial. The control is called Dial direction during Tv/Av; it’s typically in the camera’s orange Custom Functions menu area. With the default dial operation, as viewed from the rear of the camera, rotating the dials counterclockwise adds light and clockwise subtracts light when the camera is set to Manual exposure.
For me, and most of the photo students who have attended my field workshops, this is confusing. Turning the dial left (counterclockwise) to increase the exposure and make the histogram data move right is counterintuitive — and also, because the analog meter scale in the viewfinder “moves” in the opposite direction from the dials’ rotation. It is easier to remember to turn the dials the same direction you want the histogram data to move.
3. Exposure Level Increments
Your camera may allow you to set full, 1/2, or 1/3 stop increments for the shutter speed, aperture, and sometimes the ISO. I suggest 1/3-stop increments for precision, and this is the factory-default setting for shutter speeds and apertures with Canon cameras. Some cameras only allow full stop increments with the ISO. I could live with it easily, but still prefer 1/3-stop increments for all three exposure controls.
4. Use the Evaluative Metering Mode
Canon cameras offer metering modes that usually include evaluative, spot, partial, and center-weighted averaging. These options were important in the film days, but far less so today. I once used spot metering exclusively, but with the histogram and highlight alert, I find evaluative metering is sufficient for all the images I shoot. Evaluative reads most of the picture area, and performs numerous calculations to arrive at the ideal exposure much of the time. Even when it isn’t optimum, evaluative is seldom very far off.
5. Don’t hesitate to deliberately make exposures brighter or darker than the standard exposure as needed
If the exposure requires compensation, do it manually if using Manual exposure by turning the aperture, shutter speed, or even the ISO while watching the indicator on the exposure scale seen in the viewfinder. If using any auto-exposure mode, then use the camera’s exposure compensation control (EC) for ambient light. With most Canon EOS models, this is by turning the large Quick Control Dial on the back of the camera. EOS Rebel models require pushing a +/- button, holding it in, and turning the Main Dial on top of the camera. Either way, the analog scale in the viewfinder shows the amount you’ve altered exposure.
Excellent Methods for Exposing Wildlife
Wildlife photos usually demand focal lengths of 300mm and longer to make the subject large enough in the image. Both camera and subject movement make capturing sharp images far more challenging with these longer lenses. Of the exposure controls — ISO, aperture, and shutter speed — shutter speed is usually the most critical factor among wildlife photographers, because fast shutter speeds deliver the sharp images we seek. Even if we must raise the ISO considerably, or shoot with less depth of field than we would like, shutter speed still is the priority.
Although cameras offer wonderful automatic modes for focusing and exposure, accomplished wildlife photographers commonly use Manual exposure in many situations, especially when the ambient light is fairly steady in brightness. Manual exposure is simple, precise, and most of all, this exposure mode maintains the set exposure in difficult shooting situations.
For example, I frequently photograph water birds in my floating photo blind early in the morning and late in the evening. I use Manual exposure exclusively for this, because many subjects have large areas of white feathers, and the amount of white appearing in the image varies considerably and quickly — this causes exposure problems with automatic exposure modes. Plus, the background against the bird can change from light blue reflected sky to dark green reflections of shoreline vegetation in an instant as it swims along. This throws auto-exposure off.
In the Manual mode, I set the exposure scale seen in the viewfinder to the zero or null setting, point the lens at the target and fire a quick shot. I look for blinkies on the LCD. If none are present, I know I must add a little light so I might rotate my dial two clicks (2/3-stop) and shoot another image. If only a few blinkies show up, then I call that a fine exposure and concentrate on composing and focusing the subject. If too many blinkies appear, then I reduce the exposure a little and try again. Normally, I get the preferred exposure dialed in with two or three sample shots.
Of course, when using Manual exposure, the photographer must be aware if the ambient light level changes and compensate for this change when it does. With my wildlife photography at dawn, naturally the sun is a little weaker at first light and slowly becomes brighter. Over an hour, I gradually get to use more shutter speed, stop the lens down more, lower the ISO, or any combination to maintain the ideal exposure. I merely monitor the highlight alert as the ambient light increases at dawn and decreases in the evening. It is not difficult to do and all my exposures are exactly what I want.
Here is how and why I use Manual exposure much of the time for wildlife. First, I set the shutter speed I want, and then I also set the aperture and ISO to give me the exposure I desire. Shutter speed is critically important and varies with the situation. When shooting on a bean bag supported on the door of an open car window, or the roof of a safari vehicle in Kenya, I feel confident I can make a sharp image even with a super-telephoto lens such as the Canon 600mm f/4.0 with a shutter speed of 1/250th second. For flying birds, I select at a minimum 1/1000th second and often use faster shutter speeds when bright sun makes that option viable.
The beauty of Manual exposure is that the camera can’t change the exposure without your permission, unlike all other auto-exposure modes. Why is this important in wildlife photography? Imagine a bald eagle with a brilliant white head and tail is soaring overhead against a blue sky while using any of the automatic exposure modes. Automatic modes are designed to produce a standard exposure close to middle-tone. If the eagle is properly exposed against the medium blue sky, but suddenly a white cloud becomes the background as it flies onward, the meter instantly recalculates the exposure to meet the standard exposure and underexposes the eagle. Should the background become a dark forest, once again the camera averages the scene and now overexposes the eagle’s white feathers. With Manual exposure, once it’s been set properly, the exposure remains optimum no matter what the brightness of the background becomes! Changing background brightness values are a common wildlife photography problem when photographing flying, running, or swimming animals.
Another problem solved with Manual exposure occurs when the size of the subject relative to the background changes. Bison are plentiful in Yellowstone during winter and their chocolate brown fur is much darker than the clean white snow around them. With any automatic exposure mode, if the optimum exposure is set while the dark bison fills 1/3 of the image, and it walks closer to fill the image more, the camera changes the exposure without any input from you to make the exposure too light. Once again, it is averaging out the tones measured by the exposure meter. Should the reverse happen and the dark bison gets smaller in the image, the camera “sees” more white tones and reduces the exposure with an underexposed bison as the result. With Manual exposure, once the optimum exposure is set, the camera continues to shoot excellent exposures no matter how much or little space the dark bison occupies in the snow scene.
Drawbacks to Manual Exposure
- You must learn how the three manual exposure controls — aperture, shutter speed, ISO — work together.
- You must learn where these controls are on your camera.
- Unlike auto-exposure modes, such as Aperture- or Shutter-Priority, Manual exposure does not adjust the exposure when ambient light levels change. If the light dims due to a passing cloud diffusing the sun, or if the light brightens, you must notice this change and manually change the exposure.
In the field, changing ambient light levels aren’t that much of a problem. Most of the time, wildlife photography is done in steady light. For example, you might visit a national wildlife refuge early in the morning to photograph the geese flying out to a nearby cornfield. It is a sunny clear morning, so you start photographing when the sun is bright enough to let you use the exposure controls desired. As the sun rises, it will get a little brighter, but this increase is gradual over a couple of hours. As you photograph, monitor the histogram or the highlight alert as I do, and make exposure adjustments when the exposure aids indicate that is necessary. It is simple to do. In my case, if my exposure was set to f/5.6, 1/1000th second, at ISO 800, and I noticed I was getting more blinkies appearing on the camera’s LCD, I reduced the exposure by stopping down to perhaps f/6.3 to gain a little more depth of field. Of course, I could also increase the shutter speed or reduce the ISO 1/3-stop if I thought either of those two options were more desirable.
Manual exposure works tremendously well for most wildlife photography, but not all. There are times when ambient light levels vary significantly and quickly. When photographing on a windy, partly cloudy day where the sun continually moves in and out of the clouds, the ambient light levels rapidly become lighter or darker. This is a time to use an automatic mode because these modes adjust for changing light levels, but here again there are many worthwhile options. Light levels also change rapidly when photographing from a boat or safari vehicle as you move from shady to sunny spots. In each case, what commonly happens is you may be photographing an animal in the dawn sunshine, but then move and go around a corner of a cliff or behind a tree and find another worthy subject in the shade. The exposure instantly becomes two or more stops darker than it was in the sunshine. In these cases, auto-exposure modes work far better than manual.
Automatic Exposure Modes and Options
Shutter-Priority is beneficial when ambient light levels change quickly. This exposure mode keeps the shutter speed you select, while the aperture automatically varies to produce the desired exposure. This has been my preferred way to photograph Kenya wildlife from a bean bag on a safari vehicle. I manually set the shutter speed to 1/500th second, sometimes more or less depending on the focal length in use, and start with the standard exposure produced by the camera. If the overall scene is brighter or darker than normal, then I adjust the exposure compensation value. A scene with a herd of zebras in light-colored grass, for instance, may need an exposure compensation (EC) of +1-stop of light to achieve the optimum exposure. When ambient light levels change, the camera adjusts the aperture to compensate. The important thing is the shutter speed is maintained to produce sharp images.
However, keep in mind there is a problem if the ambient light diminishes too much. If you are using the popular Canon EF 500mm f/4L IS II USM lens, for instance, and the ambient light declines requiring an aperture larger than f/4.0, there is no way for the camera to keep opening the lens aperture further. The camera will shoot, and warn you with a blinking aperture display in the viewfinder. Of course, if you notice this has happened, then you could reduce the shutter speed, increase the ISO, or a combination of both. But, from a tremendous amount of experience, I know most don’t remember to do any of this when a subject unexpectedly appears and you must react instantly. Most folks shoot away and find out later their images are underexposed.
To overcome this problem, an option that forces the camera to compensate properly is Safety Shift. If the camera must change the shutter speed since the aperture cannot be opened any more, an activated safety shift will slow the shutter speed to produce a desirable exposure. Of course, if the shutter speed slows too much, many images may not be sharp.
Manual exposure and Auto ISO
Is it an auto or Manual exposure mode? I call it an auto mode. True, the aperture and the shutter speed are manually set and locked to that value, but the ISO varies to produce the standard exposure.
Many accomplished wildlife photographers use Manual exposure in conjunction with Auto ISO. Why? This method lets you select the most desirable shutter speed and f-stop and lock that in. The ISO automatically varies to produce the standard exposure, if and when lighting changes. This system is effective, and I use it frequently for wildlife where exposure compensation is not that critical, because my former Canon cameras did not allow me to use exposure compensation with this combination. In places where exposure compensation is often necessary — polar bears in the snow, penguins perched on ice, or dark birds against cloudy skies — being unable to intentionally lighten and darken final exposure is a problem.
However, lately I frequently use manual exposure and Auto ISO. And my new Canon cameras, the EOS-1D X Mark II and 5D Mark IV, permit exposure compensation while using this combination. If I set the exposure compensation (EC) to +1-stop, for example, the camera doubles the ISO to produce an image one stop brighter than otherwise. Remember, the aperture and shutter speed are set manually and remain there unless you change it, but the Auto ISO allows the ISO to vary as conditions change.
A quick note: on cameras like the EOS 5D Mark IV, to apply exposure compensation with Auto ISO in the Manual exposure mode, you have to change the function of a button, using the “Custom Controls” feature in the camera’s Custom Functions menu. You then press that re-configured button, hold it in, and turn the Main Dial on top of the camera to lighten or darken exposure deliberately.
If your camera model does not allow exposure compensation when setting the shutter speed and aperture manually while using Auto ISO, another highly effective option might be available.
Aperture-Priority and Shutter Speed Limits
Aperture-Priority keeps the selected aperture while the shutter speed varies to maintain a suitable exposure. The big problem with this exposure mode for wildlife is a shutter speed that slows too much for sharp images. There is a way to use Aperture-Priority and not let the shutter speed slow down too much. If you feel, for example, that a shutter speed of 1/500th second is sufficient, then some newer, high-end Canon cameras let you Set Shutter Speed Range. Again, it’s usually a setting located in the Custom Functions menu area.
Merely setting the camera so the slowest shutter speed selectable is 1/500th second does the trick. Of course, in many cases the light isn’t sufficient to optimally expose the subject with a shutter speed of 1/500th second and your preferred aperture of f/8.0. To counteract this, set the camera to Auto ISO and all is well, though, some images may be noisy in dim light when very high ISOs are selected. Helpfully, both Shutter-Priority and Aperture-Priority allow exposure compensation with all Canon cameras.
Let’s summarize this exposure method.
- Set the camera to Aperture-Priority and f/8, or whatever aperture you prefer
- Go to the in-camera menu, find Set Shutter Speed Range, and set the minimum shutter speed to 1/500th second
- Set Auto ISO
- Use the exposure compensation control to adjust the exposure when necessary.
Master exposure so you can concentrate on focus, composition, shooting angle, and finding great wildlife subjects. The digital tools offered by the histogram and the highlight alert makes it quick and easy to arrive at the exposure that will produce fine images.