Like a prism, the triangular edge of a lens bends blue light more than red light. Blue light is therefore brought to a focus closer to the lens than red light resulting in a color distortion called CHROMATIC ABERRATION. Mirrors do not exhibit chromatic aberration.

Giant Lens
Rainbow Edges in a Lens
Rainbow Edges in Your Eye

Aberration - Astigmatism
Aberration - Barrel
Aberration - Coma
Aberration - Curvature of Field
Aberration - Pincushion
Aberration - Spherical

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