Question

The main reason for axial chromatic aberration in the formation of images by a lens is/are:

• A. focal length of lens is different for different colors.
• B. the material used to make the lens is not uniform.
• C. different sections of the lens are of different thickness.
• D. all of the above.

Answer 1

Answer: (A)

Chromatic aberration, also known as “color fringing” or “purple fringing”, is a common optical problem that occurs when a lens is either unable to bring all wavelengths of color to the same focal plane, and/or when wavelengths of color are focused at different positions in the focal plane. Chromatic aberration is caused by lens dispersion, with different colors of light traveling at different speeds while passing through a lens. As a result, the image can look blurred or noticeable colored edges (red, green, blue, yellow, purple, magenta) can appear around objects, especially in high-contrast situations.
SO the maain reason is focal length of lens is different for different colors.