depth of field

The size (or depth) around the focal point that the camera remains in focus—or, the distance between the closest and farthest objects in a photo that remain acceptably sharp. A shallow, narrow, or thin depth of field results in a faster growing blur from the focal point; while a deep, wide, or large depth of field reduces incremental blurring and produces a sharper image even for items that are out of focus.

The point at which the subject of a picture is considered acceptably within focus is known as the circle of confusion. Clearly defined intersections of cones of unfocused light that are captured in the final image are known as bokeh.

The size of the aperture and overall lens construction determine the depth of field. A larger aperture results in a deeper depth of field, as more light is able to enter the lens, including more direct light from the surrounding objects. Conversely, a shallower depth of field receives less direct light from surrounding objects, making them blurrier, and increasing depth of field.