Objects on the wall can be illuminated with an angle of incidence of 30° to 45° to the vertical. The steeper the incident light, the more vivid the object appears. On reflective surfaces, e.g. artworks behind glass or oil paintings, care must be taken that the angle of incidence does not cause secondary glare in the observer's line of vision. In addition, unwanted shadow, e.g. cast by the picture frame onto the picture surface, should also be avoided.