Certified Professional Photographer (CPP) Practice Exam

What does a larger f-stop number indicate about the lens opening?

1. Wider opening

2. Narrower opening

3. Most versatile setting

4. All settings equal

The correct answer is: Narrower opening

A larger f-stop number indicates a narrower opening in the lens. The f-stop scale is a way to express the diameter of the aperture opening, which controls the amount of light that enters the camera. As the f-stop number increases, the size of the aperture decreases, resulting in less light hitting the camera sensor. This is because the f-stop value is a fraction, with larger numbers representing a lower ratio of the lens diameter to the focal length, meaning the lens opening itself is physically smaller. This understanding is essential for photographers as it affects exposure and depth of field. A narrower opening (higher f-stop number) not only restricts light but also increases the depth of field, allowing more of the scene to be in focus. In contrast, a smaller f-stop number indicates a wider aperture, which lets in more light and creates a shallower depth of field, often used for portraits to blur backgrounds. Recognizing how f-stop numbers correlate to aperture size is crucial for effectively controlling exposure and artistic impact in photography.