Certified Professional Photographer (CPP) Practice Exam

Which size of lens opening contributes to a shallower depth of field?

1. Smaller

2. Larger

3. Medium

4. Variable

The correct answer is: Larger

A larger lens opening contributes to a shallower depth of field because it allows more light to enter the camera, which in turn results in a more pronounced background blur. When the aperture is wide open (represented by a smaller f-stop number, such as f/2.8), it focuses more light onto the image sensor and decreases the area in front of and behind the subject that appears in focus. This effect is often desired in portrait photography, where isolating the subject from a blurry background enhances the subject's prominence in the composition. In contrast, smaller lens openings increase the depth of field, making more of the scene appear in focus, while medium and variable openings can produce varying results that don't necessarily favor a shallower depth of field. Understanding the relationship between aperture size and depth of field is crucial for photographers aiming to achieve specific artistic effects in their images.