Demo 22-21 Spherical Aberration

A lens that has a spherical shape will exhibit spherical aberration; the position at which parallel light rays focus is closer to the lens for rays further away from the optic axis. When a stop is placed over the outer part of the lens and the distance between the lens and the image slightly adjusted, the aberration is significantly reduced, as shown in Figure 1. If a stop is placed on the center of the lens, leaving the outer part of the lens open, and the position of the lens again adjusted, the image is again clearer than that with the entire lens open, as nicely shown in the video