How many main factors control depth of field?

• A. Focal length of lens, aperture, and camera to subject distance
• B. ISO, shutter speed, and white balance
• C. Sensor size, megapixels, and aspect ratio
• D. Color temperature, contrast, saturation

Answer: (A)

Depth of field is shaped by three factors: the lens aperture, how close you are to the subject, and the focal length of the lens. A larger aperture (smaller f-number) gives a shallower depth of field, while a smaller aperture (larger f-number) increases it. Being closer to the subject reduces the depth of field, and moving farther away increases it. A longer focal length also tends to produce a shallower depth of field for the same framing, whereas a shorter focal length increases it. The option lists these three controls directly, which is why it’s the best choice. The other groups—exposure settings like ISO and shutter speed, or color adjustments like white balance and saturation—affect exposure or color, not depth of field.