observation zone, size of picture and optimal viewing angle (fig. on left) are the parameters defining
the optimal position of a wall-lighting luminaire. The upper edge of the picture determines the spotlight
opening angle (B: 30°, C: 60°) with a constant angle of inclination of 30°. Angles less than 30° can
result in reflections at the upper edge of the picture (critical observation zone). The mathematical
formula for calculating the distance “x” between spotlight and wall for illuminating a picture with the
height “y” is: x = y tan 30°