What is the relationship between aperture size and depth of field?

The correct answer highlights that a smaller aperture increases depth of field. When the aperture size decreases, such as when you use a higher f-stop number, more of the scene, both in front of and behind the point of focus, becomes sharply in focus. This effect is crucial in situations where you want maximum sharpness throughout the frame, such as in landscape photography where everything from the foreground to the background should be clear.

In practical terms, when you use a smaller aperture (like f/11 or f/16), the lens creates a greater range of distances that appear acceptably sharp. This is because the smaller opening allows for less light to enter the camera, which increases the sharpness of the image across a broader range of distances due to the way light diffracts.

This principle plays a significant role in photography as it allows photographers to control how much of the scene is in focus, thereby influencing the mood and composition of the image. In contrast, larger apertures (like f/1.8 or f/2.8) yield a shallower depth of field, which is often desirable for portraits or subject isolation but does not serve the same purpose as a smaller aperture does in expanding the depth of field.