Certified Professional Photographer (CPP) Practice Exam

Which type of distortion occurs when a lens cannot focus the wavelengths of all colors to the same point?

1. Focal distortion

2. Chromatic aberration

3. Barrel distortion

4. Pincushion distortion

The correct answer is: Chromatic aberration

Chromatic aberration occurs when a lens fails to focus all wavelengths of light to the same convergence point, leading to a discrepancy in how colors are rendered in an image. This phenomenon typically arises because different colors of light have varying wavelengths and therefore different focal lengths within the lens system. As a result, this type of distortion manifests as fringes of color along the edges of high-contrast subjects, most commonly seen in areas of light and dark contrast in the photograph. For instance, a white object against a dark background may show a noticeable halo of color around the edges, illustrating chromatic aberration. Understanding chromatic aberration is crucial for photographers as it impacts image quality, particularly in high-contrast scenarios. The ability to recognize and mitigate chromatic aberration—through lens selection, careful focusing, or using software correction—can enhance the overall clarity and professionalism of the photographic work. Other types of distortion mentioned, like barrel and pincushion distortion, refer to geometric distortions related to lens shape rather than color focusing issues.