Certified Professional Photographer (CPP) Practice Exam

Which filter would you use to darken a blue sky?

1. Neutral density filter

2. Polarizer

3. Graduated filter

4. Color correction filter

The correct answer is: Polarizer

Using a polarizer filter is an effective way to darken a blue sky. This filter works by reducing reflections and glare from surfaces, which enhances color saturation and contrast in the sky. When a polarizer is rotated, it can selectively filter out light waves that are scattered, resulting in a deeper, more vibrant blue in the sky while also helping to create more defined clouds. In contrast, while other filters have their specific uses, they would not provide the same effect on the blue sky. A neutral density filter is primarily used to reduce the overall amount of light entering the lens without affecting color balance, making it less effective for enhancing sky colors specifically. A graduated filter is typically employed for balancing exposure between the sky and the foreground but does not enhance the blue in the same way a polarizing filter does. A color correction filter is used to adjust color temperature and correct color casts rather than specifically darkening or enhancing specific hues in a scene.