Every experienced photographer will have his or her own preferred exposure mode and reasons for the preference. Most novices will be comfortable with shooting in fully automatic or Program mode. In the field of bird photography, however, the fast-moving subjects and challenging, varying lighting conditions will reduce your chances of taking outstanding photos when shooting in a mode that lets the camera make all the decisions.
Learning to take control of your exposure settings will help you create consistently beautiful bird photos. You'll first need to understand the three elements of exposure and how they work together. If you're not familiar with them, we highly recommend starting by learning the Exposure Triangle. You'll find a full explanation of it in this article.
There are three basic shooting modes that give you the most creative control. Each of these modes can have advantages in a particular shooting situation. Let's look at each mode and how it can provide an advantage when photographing birds. First, here's how each mode works:
NOTE: If your DSLR camera offers an Auto setting for ISO, we recommend that you do NOT use it for bird photography. This will ensure that you avoid ISO ranges above those where noise is kept to a manageable level in your camera. It's important to know the limitations of your camera and stay within them for the best results.
Full Manual (M): You select ISO, aperture size and shutter speed.
Aperture Priority (A or Av): You select ISO and aperture size and the camera selects the shutter speed.
Shutter Priority (S or Tv): You select ISO and shutter speed and the camera selects the aperture size.
As you can see from the basic explanations above, Av and Tv modes rely on the camera's metering system to calculate the proper exposure. There are ways to bias the metering system, including exposure compensation, which we'll outline later in this lesson.
As explained above, each of these exposure modes can be effective in certain situations. Here's how they're most useful:
Obviously the most challenging exposure mode in any genre, manual (M) exposure mode is the most difficult to master and the slowest to adjust. There is one particular instance in which manual exposure settings can work to your advantage. When lighting conditions are fairly constant and you're shooting the same subject or subjects with roughly the same level of brightness, locking in the correct exposure setting will avoid fluctuations in settings from slight shifts in lighting caused by using one of the automatic exposure modes. This allows you to maintain your settings for exposure to the right.
For example, let's say you're shooting a number of egrets in one location. You've got a great spot to shoot from and the birds aren't moving away. You can select the optimum ISO, aperture and shutter speed settings for your needs and continue shooting without worrying about metering for each shot. If the sun drops a bit lower, you can make a minor adjustment and resume shooting.
This method leaves the least margin for error, but it's important to know your equipment and how to set your exposure manually very well to use it efficiently.
This might seem to be the first choice for a genre with subjects that often move fast. Unfortunately, that's rarely the case.
In theory, you simply select a high enough shutter speed to freeze the action of your subject, then an ISO setting that won't create too much noise in the image and let the camera adjust the aperture setting. In low light however, there will be times when the aperture setting required to balance the exposure will be wider than your lens is capable of. With many digital cameras, this underexposure condition will prevent the shutter from operating and give you a visual and/or audible warning. For those that don't prevent the exposure, missing the warning may result in images that are too dark to use. This situation means pushing the ISO setting higher, which may result in too much noise in the image.
When using this mode in bright conditions, aperture settings will shift toward the higher (smaller) end of the scale. While this may not seem to be an issue, it's important to know at what aperture setting your lens is prone to diffraction, which can reduce the sharpness of your image. Smaller aperture settings may also extend the depth of field of your image to the point that your subject isn't well isolated.
Shutter priority mode is best used only when lighting conditions are optimal for best results.
For speed and consistent results, this is the preferred mode for many professional and amateur bird photographers. Aperture priority lets you select an acceptable ISO setting, then adjust the aperture for the depth of field you want to produce in the shot, while avoiding the aperture ranges that produce diffraction effects. You then let the camera select the shutter speed to maintain proper exposure.
The obvious drawback to this method is the possibility of shutter speeds that are too low to avoid motion blur from the movement of a subject and/or the camera. Image stabilization will help somewhat with camera shake, but little can be done about the movement of your subjects.
When shooting in this mode with moving subjects, it's important to keep your eye on the selected shutter speed when you press the shutter button halfway and adjust if it falls beneath 1/160s. Remember, however, that some blur may enhance certain shots, for instance, a little blurring in the wings of a bird in flight.
When shooting in aperture priority or shutter priority mode, you have the option of using exposure compensation on your DSLR camera to adjust the camera's metering system. While the best usage of this setting is to adjust for those lighting conditions that can “fool” your camera, such as strong back-lighting, it can also be used to push the setting your camera is selecting up or down to adjust for the scenarios mentioned above.
When you use exposure compensation to adjust for these scenarios, you'll need to understand that you'll be creating an image that's too dark or too light and will need to correct it in post processing. That means this method is only useful within a certain range, before the image will be beyond correcting.
It's possible in some bird photography supplemental lighting to help expose your shots properly. The most practical source of that lighting is a flash head, and we'll discuss using flash in the next lesson.