21. The distortion includes chromatic and spherical aberration and diffraction, as well as structural flaws in the outer lens. 22. These tests correctly reported spherical aberration , but were dismissed since the reflective null corrector was considered more accurate. 23. If the mirror is made parabolic, to correct the spherical aberration , then it must necessarily suffer from astigmatism. 24. It had almost no flaws, except for a bit of oblique spherical aberration , which could lower peripheral contrast. 25. The asphere's more complex surface profile can reduce or eliminate spherical aberration and also reduce other collimating diode lasers. 26. The spherical aberration of the cornea is usually positive whereas the young crystalline lens exhibits a negative spherical aberration. 27. The spherical aberration of the cornea is usually positive whereas the young crystalline lens exhibits a negative spherical aberration . 28. The geometric collecting area of each telescope is about 25 cm2, with spherical aberration limiting resolution to about 0.25�s. 29. Of thin positive lenses with n = 1.5, four are necessary to correct spherical aberration of the third order. 30. The caustic formed by spherical aberration in this case may therefore be described as the evolute of a Cartesian oval.
