A: Aperture Priority Mode
Probably the mode most widely used by professional photographers, Aperture Priority is one of my personal favorites, and I believe that it will quickly become one of yours. Aperture Priority mode is also deemed a semiautomatic mode because it allows you to once again control one factor of exposure while the camera adjusts for the other (Figure 4.11).
Figure 4.11. Use Aperture Priority mode when you need to control depth of field. This is my favorite shooting mode.
Why is this one of my favorite modes? It’s because the aperture of your lens dictates depth of field. Depth of field, along with composition, is a major factor in how you direct attention to what matters in your image. It is the controlling factor of how much area in your image is sharp. If you want to isolate a subject from the background, such as when shooting a portrait, you can use a large aperture (low f-stop number) to keep the focus on your subject and make both the foreground and background blurry. If you want to keep the entire scene sharply focused, as with a landscape scene, then using a small aperture (high f-stop number) will render the greatest amount of depth of field possible.
When to use Aperture Priority (A) Mode
- When shooting portraits or wildlife (Figure 4.12)
Figure 4.12. The lizard was very still so I was able to use a tripod and zoom in tight. The large aperture helped create a smooth, blurry background, also known as bokeh.
- When shooting most landscape photography (Figure 4.13)
Figure 4.13. The smaller aperture setting brings sharpness to near and far objects.
- When shooting in bright skies consider silhouetting an image (Figure 4.14)
Figure 4.14. Using a very small aperture on a clear blue day, I was able to create this sunburst. Typically f/16 or higher will do the trick! Give it a try. The key ingredient is a clear sky, because clouds will diffuse the sun.
- When shooting cityscape photography, which often benefits from a large depth of field (Figure 4.15)
Figure 4.15. I wanted the foreground as well as the background in focus, so I used a wide-angle lens combined with a small aperture to maintain focus throughout the image. This is called a deep depth of field.
I strongly recommend knowing your lens’s aperture rating. Every lens has a marking on it with a number; f/1.4, f/2.8, or f/5.6 are all very common maximum aperture sizes. This number simply means the largest aperture your lens supports is f/1.4, f/2.8, or f/5.6, respectively. The D7100 kit ships with a standard 18–105mm lens with an f/3.5–f/5.6 variable maximum aperture (Figure 4.16).
Figure 4.16. It’s important to know the focal range and maximum aperture of your lens.
Knowing the limits of your lens aperture is crucial when using Aperture Priority. As a general rule, the lower the number on the lens, the “faster” it is (because it allows more light in to expose the image, thus reducing the amount of shutter time) and the sharper the image is. Typically, fast lenses are heavier and more expensive, but they’re well worth the investment if you find yourself shooting in low-light conditions. The larger the aperture is, the better the exposure without having to increase ISO and introduce digital noise.
On the other hand, bright scenes require the use of a small aperture (such as f/16 or f/22), especially if you want to use a slower shutter speed. That small opening reduces the amount of incoming light, and this reduction of light requires that the shutter stay open longer.
Setting Up and Shooting in Aperture Priority Mode
- Turn your camera on and then turn the Mode dial to align the A with the indicator line.
- Select your ISO by pressing and holding the ISO button on the back left of the camera while rotating the main Command dial with your thumb.
- The ISO will appear on the top display. Choose your desired ISO, and release the ISO button on the left to lock in the change.
- Point the camera at your subject and then activate the camera meter by depressing the shutter button halfway.
- View the exposure information in the bottom area of the viewfinder or by looking at the top display panel.
- While the meter is activated, use your finger to roll the Sub-command dial left and right to see the changed exposure values. Roll the dial to the right for a smaller aperture (higher f-stop number) and to the left for a larger aperture (lower f-stop number).