Which setting primarily controls the amount of light reaching the sensor?

• A. Aperture
• B. Shutter speed
• C. Iso
• D. White balance

Answer: (A)

Aperture directly controls how much light enters the camera by changing the size of the lens opening. A wider opening (lower f-number) lets more light reach the sensor, brightening the image; a narrower opening (higher f-number) reduces light and darkens the image. While shutter speed and ISO also affect exposure—shutter speed by controlling how long the sensor is exposed, and ISO by adjusting sensitivity—they influence brightness in different ways and aren’t the primary means of limiting or admitting light. White balance affects color, not brightness. So, the setting that primarily controls the amount of light reaching the sensor is the aperture.