</noinclude> [[Image:Spherical aberration 2.svg|thumb|300px|Spherical aberration. A perfect lens (top) focuses all incoming rays to a point on the optic axis. A real lens with spherical surfaces (bottom) suffers from spherical aberration: it focuses rays more tightly if they enter it far from the optic axis than if they enter closer to the axis. It therefore does not produce a perfect focal point. (Drawing is exaggerated.)]] Lenses with surfaces that are spherically shaped are easier to manufacture, but they have a flaw that the light that travels through the lens near the center focuses at a different point than the light that travels through the lens near the edge.
