1. | Opening for light to enter | Aperture | Pupil |
2. | Control the amount of light entering camera/eye | Diaphragm control size of aperture | Iris muscles control size of pupil |
3. | Refract light | Glass biconvex lens | Mainly cornea ; lens, aqueous & vitreous humor |
4. | Object of light action to form image | Photosensitive chemicals on film | Photo receptors(rods & cones) in retina |
5. | Absorb excessive light to prevent multiple images formation | Dark internal surface | Pigmented, dark choroid |