optical test of telescopes and camera lenses

from takashi suzuki

the more clearly the colors are separated from one another by a vertical central axis, the more a refractor tends for achromatic. The more the colors are crescent-shaped and the whiter the overall impression is, the more clearly a lens tends towards APO.

knife edge, or foucault tests:

The curvature of the Ronchi fringes mainly represent the amount of spherical aberration, but it increases in proportion to the F number.

If the amount of aberration is the same, the curvature of the Ronchi fringes of the F10 optical system will be twice as much as that of the F5 optical system . At first glance, the shorter focal ratio telescopes will appear to have less aberration, so take note .

from rohr

SLR or DSLR lens from ERphotoreview

有比較就有傷害，好不好

ronchi and foucault tests in rohr's website