Controlling SA
Since spherical aberration is caused by the difference in focal length between the center and the edge of a lens, why don't we just make all the light pass through the center? In fact, when you stop a lens down to, say f/ 32, you're doing exactly that.
In practice, homemade lenses can produce unexpectedly sharp images when stopped down to f/ 16 and beyond.
These two images should give you a sense of this. Both were shot using the same simple homemade lens made from a 75 mm achromat.
The image on the left was shot at f/ 1.5.
The one on the right was shot at f/ 10.