Observe these spots of light and note the following:
- Some spots are more luminous than others;
- When the spots overlap, their intersection is more luminous;
- The light spots have a soft edge rather than a hard edge;
- Spots of lights are subject to the law of perspective and are seen as ellipsis from a distance.
But why are these spots round when the holes between the leaves are not? The answer is that these round spots of lights are the sun projected on the ground. The physics is the same as for the pinhole camera.
So, if each spot of light is a projection of the sun, their shape would be different during a solar eclipse. This is correct: the spots become crescents of light.
Image of the sun during a solar eclipse through the leaves of a tree. October 3, 2005, St Juliens, Malta – picture by User:Ellywa - Source: Wikimedia Common
Dapple light is a good way to bring variety to a landscape or a scene. You can selectively bring some elements of the subject under the spotlight. The difficulty is to avoid having a patchwork of colours and tone without any focus. Renoir used dapple light in an effective way in his painting Bal du moulin de la Galette.
Bal du moulin de la Galette by Auguste Renoir (Oil on canvas - 1876) Musée d'Orsay – Source: Wikimedia Common