How do compound lenses reduce image distortion?

A compound lens reduces image distortion—referred to in physics as aberrations—by combining multiple individual lens elements into a single, precisely aligned unit.1

Single lenses often fail to focus light into a perfect point, instead creating a small, blurred patch of light. To correct these innate imperfections, designers combine several elements that may vary in shape (convex or concave) and material properties, such as refractive index or dispersive power. By carefully calculating the separations between these elements or cementing them together, the system can counteract the aberrations produced by individual lenses.1

For example, compound lenses are specifically engineered to address chromatic aberration by using different materials to bring various colors of light to a common focal point. This precise coaxial arrangement ensures that the final image achieves the sharpness and resolving power required for high-precision instruments like cameras, microscopes, and telescopes.1