Abstract

Field experiments show that a wire may be seen against a sky of high brightness when its diameter subtends only half a second of visual angle. For this the wire must be at least one degree long. Shorter wires must be thicker. Silhouetted squares may be seen at angles of only 18 seconds. Considering length and width, squares are more efficient visual targets than fine lines by about a factor of 3.

© 1947 Optical Society of America

Size, Shape, and Contrast in Detection of Targets by Daylight Vision. I. Data and Analytical Description1

Edward S. Lamar, Selig Hecht, Simon Shlaer, and Charles D. Hendley
J. Opt. Soc. Am. 37(7) 531-545 (1947)

Photographic Granularity and Graininess*III. Some Characteristics of the Visual System of Importance in the Evaluation of Graininess and Granularity

Loyd A. Jones and George C. Higgins
J. Opt. Soc. Am. 37(4) 217-263 (1947)

The Change in Refractive Power of the Human Eye in Dim and Bright Light

George Wald and Donald R. Griffin
J. Opt. Soc. Am. 37(5) 321-336 (1947)

The Relation of the Configuration of a Brightness Contrast Border to Its Visibility

Glenn A. Fry
J. Opt. Soc. Am. 37(3) 166-175 (1947)

The Two-Quanta Explanation of the Dependence of the Threshold Values and Visual Acuity on the Visual Angle and the Time of Observation

M. A. Bouman and H. A. van der Velden
J. Opt. Soc. Am. 37(11) 908-919 (1947)