By using actual sightlines of desk worker, we investigate mounting positions of the lighting equipment on ceiling and the contrast rendering ratio of task on desk. The results show that we make wrong estimates of visual conditions of desk worker if binocular condition is not taken into consideration and a fixed eye point is assumed. Luminance difference threshold measured under binocular condition differs from the one under single eye. However, if there is significant difference in stimulus between left and right eye, the visibility may be almost determined by an eye that has better sensitivity.
