Question

All eyeglass lenses have chromatic aberration. This is usually expressed as dioptric spread. For a typical +6.0 D lens, the focusing power for red light is +5.90 D, the power for green light is +6.00 D, and the power for blue light is +6.10 D. This gives a dioptric spread of 0.20 diopter. Suppose a myopic person is observing a distant object through this lens, and the green light of the image is in perfect focus. Assume a distance s′ = 1.7000 cm.

a] How far in front of or behind the retina is the point of sharp focus for red light? (answers 1.889, -1.889 do not work)

b] How far in front of or behind the retina is the point of sharp focus for blue light? (answers .004 or 1.893 do not work)

Answer 1