Which parameter controls depth of field in a typical camera exposure?

• A. Shutter speed
• B. ISO
• C. Aperture
• D. Focal length

Answer: (C)

Depth of field describes the range of distances in a scene that appear acceptably sharp. The camera exposure parameter that directly controls how much of the scene stays in focus is the aperture. A wider aperture (smaller f-number) gives a shallower depth of field, blurring anything outside a narrow plane of sharpness. Stopping down to a smaller aperture (larger f-number) increases depth of field, bringing more of the scene into focus. Shutter speed and ISO affect brightness and motion or noise, not the extent of sharpness across depths. Focal length and subject distance also influence depth of field, but for adjusting it in a typical exposure, the aperture is the primary tool.