Certified Professional Photographer (CPP) Practice Exam

What factor also influences exposure aside from the light present?

1. Shutter speed

2. Sensor size

3. ISO

4. Aperture

The correct answer is: ISO

The correct choice emphasizes that ISO plays a significant role in influencing exposure within photography. ISO indicates the sensitivity of the camera's sensor to light; a higher ISO value allows the camera to capture images in lower light conditions without requiring a longer exposure time. This sensitivity can dramatically affect the overall exposure of an image. For example, doubling the ISO number effectively increases the sensor's sensitivity, allowing it to register more light and resulting in a brighter image under the same lighting conditions. While shutter speed, sensor size, and aperture are also essential components of the exposure triangle—each affecting exposure in unique ways—ISO specifically pertains to the image sensor's sensitivity. This means that while the other options impact how much light reaches the sensor over time (shutter speed) or alter the amount of light entering the lens (aperture), ISO is distinct in its function of adjusting the sensor's response to that light. Therefore, understanding ISO's influence is crucial for photographers looking to manage exposure effectively, especially in varying lighting situations.