Visual acuity in light of different colours

Publisher Website
Google Scholar
Abstract
Previous work on visual acuity has shown that there is a different law relating intensity of illumination to acuity of vision for lights of low and of high intensities. Hecht has recently discussed this problem (1) basing his discussion on the measurements of König (2). König obtained poor acuity of vision with “blue” light. In view of the importance to the study of colour vision of any method of quantitative measurement, the following experiments were undertaken.Method. A bright light (A, fig. 1) was concentrated by means of a condenser (B) on a colour filter (C) and the light was concentrated on a ground-glass screen (F) by means of a lens (E). Close to the lens was a shutter (D) consisting of two sectors, each with three apertures of 60°, so that when the two sectors were superimposed with the open parts opposite to each other half the lens was exposed to light, but when one shutter was rotated so that the opaque parts of it coincided with the apertures of the other, all the light ought to have been cut off. As a matter of fact some stray light found its way past when the shutter was supposed to be entirely closed, but the amount so passing was slight.