Motion and Depth of Field
When it comes to creating compelling photographs, there are usually a number of factors at play—subject matter, location, composition, light. But there are two constants that will play a role in every image you take: motion and depth of field.
We know that shutter speed controls the length of time that light is allowed to hit the camera’s sensor, but what we haven’t talked about is how it also controls how we capture motion within an image. The less time that light has to enter the camera, the less time your subjects have to move around and become blurry. This lets you do things like freezing the motion of objects (Figure 2.9) or allowing the motion to become part of your image (Figure 2.10).
Figure 2.9. By using a fast shutter speed, you can stop motion in its tracks, such as this falling piece of glacier.
Figure 2.10. By using a slow shutter speed and moving the camera while shooting, you can create motion blur in your images.
Aperture controls the amount of light that hits the sensor, but it also controls depth of field, which is the distance between the sharp and out-of-focus areas of your image. With a smaller aperture (meaning a larger f-stop number, like f/22), you can bring more of your image into focus, giving you a greater depth of field (Figure 2.11).
Figure 2.11. I wanted sharpness in both the foreground and background of the image, so I chose a small aperture.
With a larger opening (meaning a smaller f-stop number, such as f/2.8), you can create more separation between the object of your focus and the background of the image (Figure 2.12).
As we progress through the chapters of this book, you will learn how to utilize the elements of exposure to capture not only properly exposed images, but creative and unique ones as well.