Researches in colour vision and the trichromatic theory (1913)
Abney, William de Wiveleslie, Sir, 1843-1920 · London : Longmans, Green · leaf 194
174 RESEARCHES IN COLOUR VISION increased 100 times, we have only to diminish the dia¬ meter of the aperture to one-sixteenth, and it will again disappear, or if to one-sixty-fourth, the light may be increased 1000 times. There must, of course, be some … Fig. 59. lower limit to this when the image, that of the small disc of light, which a point such as a star subtends in the retina. When the angular aperture exceeds 4°, apparently the upper limit is reached, all extinctions being the same beyond it.
Color Perception · Color blindness · Color vision
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