Certified Professional Photographer (CPP) Practice Exam

What is the relationship between ISO and shutter speed in photography?

1. ISO has no relationship

2. Lower ISO requires longer shutter speed

3. Higher ISO requires longer shutter speed

4. Higher ISO requires shorter shutter speed

The correct answer is: Higher ISO requires shorter shutter speed

In photography, the relationship between ISO and shutter speed is essential for properly exposing an image. ISO measures the sensitivity of your camera's sensor to light. When you increase the ISO setting (making it higher), the sensor becomes more sensitive, allowing it to capture images in lower light conditions more effectively. With a higher ISO, the camera requires less light to achieve a correct exposure, which means that you can use a shorter shutter speed. This is particularly useful in scenarios where you want to freeze motion, as a faster shutter speed will reduce the risk of motion blur. Thus, the interplay between higher ISO settings and shorter shutter speeds allows for better results in dynamic situations with limited light. In contrast, when using a lower ISO, the sensor is less sensitive to light, leading to the necessity of using longer shutter speeds to capture enough light for a proper exposure. The relationship is grounded in the need to balance light sensitivity and the duration the shutter remains open, ensuring the final image is well-exposed. Understanding this relationship helps photographers make informed choices to achieve the desired exposure regardless of lighting conditions.