Varying image size is more associated with which type of chromatic aberration?

• A. Lateral chromatic aberration
• B. Longitudinal chromatic aberration
• C. Spherical aberration
• D. Coma

Answer: (A)

Varying image size across colors is a hallmark of lateral (transverse) chromatic aberration. Dispersion makes different wavelengths have slightly different magnifications at the image plane, so a point can be imaged at different sizes depending on color. Longitudinal chromatic aberration shifts focal points along the optical axis with wavelength, causing axial color fringes and blur rather than a color-dependent change in image size at the image plane. Spherical aberration and coma are primarily geometric or off-axis distortions and don’t produce the wavelength-dependent magnification that changes image size.