What is the camera's sensitivity to light called?

• A. Aperture
• B. Exposure
• C. F-Stop
• D. ISO

Answer: (D)

Sensor sensitivity to light is called ISO. ISO describes how sensitive the camera’s sensor is to the light that hits it. Higher ISO numbers make the sensor more responsive, so you can shoot in dimmer conditions without longer exposure, but the trade-off is more digital noise. Lower ISO numbers keep noise down but require more light or a longer shutter to achieve the same brightness. For contrast, aperture is the opening in the lens that controls how much light enters and also affects depth of field (often described by the f-number, or F-stop). Exposure refers to the overall brightness of the image, which results from a combination of ISO, aperture, and shutter speed. In short, since the question asks about how sensitive the sensor is to light, ISO is the correct term.