I made a test of vision under the illumination of 200 H. Lux using incandescent lamps and de luxe daylight fluorescent lamps as the light-source.
Fourteen kinds, 140 sheets of Landolt's test-card in various color-contrast with black, white, green, blue, red and yellow were used as the test material. (1) In all cases de luxe daylight fluorescent lamps gave better vision than incandescent lamps. (2) The difference was 1.78% at the minimum, 26.08% at the maximum, and 9.67% in the average. (3) The marked differences were 26.08% in white object on yellow background, 25.04% in yellow object, 24.10% in red object, 11.74% in green object and 10.48% in blue object each on white background. (4) These differences are considered mainly due to the color rendoring properties of both light-sources. (5) The relation between color-contrast and vision is affected by the nature of light-sources in various degree according to the variety of coor-contrast.