均一な背景の下における順応輝度とランドルト環視力

Abstract

The purpose of this study is to investigate the visual acuity as a function of the adaptation luminance within the range from 0.005 to 4, 000 cd, /m2. A room with sufficiently wide background visual field and with uniform background luminance illuminated diffusely is set up to provide a visual environment for acuity test. The test objects are the Landort rings with luminance contrast of 92% and with in the deviations of size less than ±3% from the standard values. The obsevers are five male students with normal vision and they judge the break orientations of the Landort rings by guessing. Visual experiments are carried out according to the standard method of the visual acuity test.Results obtained are as follows.1. The equation approximating the resolutionable visual angle as a function of the 1/4th power of the adaptation luminance was obtained by the method of least squares.2. This equation shows that the visual acuities are lower than those of Moon and Spencer over the whole range of adaptation luminance, and seems to be more practical and more suitable than that of their's.3. The visual acuities in the vertical and the horizontal directions are slightly higher than those in the oblique directions.