Photo - Optics Note Book 20. Optical Formulary

EYE - (continued) Resolution Minimum resolution depends upon: (1) retinal location of the image - (resolving power decreases with distance from the fovea); (2) nature of the image - (size, shape, color, illumination and contrast); (3) adequate time for stimulation. Two small objects can be recog-nized as two when their images fall no nearer on the retina than on two non-adjacent cones providing the diffraction patterns are sufficiently separated. See "Experiments in Seeing" by Harry Asher, Basic Books, Inc. (or Fawcett publications paperback). The average eye resolves details subtending 1 minute of arc at the eye (subtending 75 u at 250 mm).