What feature of a camera allows for adjustability of light entry?

The feature of a camera that allows for adjustability of light entry is the aperture. The aperture is an opening in the lens that determines how much light passes through to the camera's sensor. It is measured in f-stops, where a lower f-stop number indicates a larger opening and more light entering the camera, while a higher f-stop number denotes a smaller opening and less light.

By adjusting the aperture, photographers can control the exposure of their images and also influence the depth of field, which affects how much of the scene appears in focus. Therefore, understanding how to manipulate the aperture is crucial for photographers seeking to achieve a desired artistic effect in their images.

The other options, while related to exposure, serve different functions. ISO pertains to the camera sensor’s sensitivity to light, and shutter speed controls the duration the sensor is exposed to light. The viewfinder, on the other hand, is simply the component that allows the photographer to frame and compose their shot, without influencing the actual light entry into the camera.