Stopping down a lens cuts off rays that would pass through the lens' outer zones. Because all the Seidel aberrations come from the lens' effects on these outer rays, removing them or stopping them improves an image. The larger a lens is in relation to its focal length, the more non-paraxial rays appear. But there's a limit to how big a lens you can make. Large lenses are very expensive not because of the amount of glass needed, but because of the cost of grinding them precisely enough over a large surface.
Optical engineers can incorporate multiple lenses in an optical system to control aberrations.
These multi-element lens designs can precisely control all of the Seidel aberrations. These lenses cost a great deal, though, due to the number of precision optical surfaces that must be ground and held at just the right spacing. Designs may include half a dozen lenses. Finally, if all else fails, a designer can opt to use lenses with one or more aspheric surfaces. Aspheric surfaces, however, are difficult to grind, although high-precision, digitally controlled grinding machines have made producing them easier than before.