A classical art training has many advantages, among which is to learn to see and understand light as it falls on objects. By accurately portraying these values, form and depth are created. One of the ways this is taught is to analyze light on a ball. Begin by acquiring a good size white ball, place it on a flat surface, and position a bright spotlight to strike it from one side. Darken the room to intensify the contrast between light and dark. Then, stand back and study the way the light hits the ball. Identify these areas: the highlight (the shiny spot of light); the area of illumination (the shape that receives the direct light from the source); the halftone (the point where the light begins to bend into shadow); the core shadow (the area where light can’t reach); the reflected light (the place where the light travels beyond the object and reflects back); and finally, the cast shadow (the shadow being cast from the shape of the object).
After these initial observations, slowly walk around the ball and pay attention to how the highlight travels across the surface of the ball while the other value shapes stay put. More or less of one value area may be visible but they aren’t moving; you are. The shiny highlight, though, seems to follow you until the ball is in silhouette. This bit of information provides one of the most profound insights into how light works. It strikes an object, falls across its surface, and creates the appearance of form but the highlight reflects off the surface and comes directly back to you. There are three factors to keep in mind: the angle of the light source, the surface or topography of the objects it is striking, and you. You are part of the equation. Highlights travel to you. To better understand this, try standing by a body of water when sunlight is sparkling off its surface. Look at your feet and you will observe that the highlights are coming to you. Walk along the shore and look again, and you’ll notice that the highlight has followed you. Just as we are always in the middle of our visual space, so too is the viewer of our paintings. Depending on where the light source is in relationship to the objects within our paintings, highlights will reflect off surfaces towards the middle.
If you spend time observing and studying the light on the ball, you will never look at a tree or rock the same way. This is why most plein air painters, who race against the moving light, start by placing the shadow shapes in their paintings. By representing the shadows, the position of the light and the surfaces it is striking will be easier to understand. Then you’ll know where to place the highlights.