Diagonals have more energy than the horizontals and verticals, they reach across images pulling the viewer’s eye with them. Diagonals lead the eye. They gives a sense of movement and can be used to creat direction and tensions. In the first of the above series the diagonal of the fence leads to the door. In the second there is a tension created by the perspective and converging lines of the handrail and the point of the satellite dish. The eye is drawn along the rail. This is a strong element, the eye is pulled to the left. The point of the satellite dish is also strong and the eye is drawn between the elements. The third picture has the angle of roof, the kerb and the railway lines. The eye follows the roof down and then along the tracks toward the distance. The kerb line also directs us toward the tracks. The road in the fourth pulls us along, there is a sense of journey and movement that follows the road.
Diagonals are easy to construct, the rules of perspective fill images with diagonals. Diagonals give photographs depth, they reach into the background.