Light will travel forever.
It is why we can see light from stars. They are millions of light years away and yet those light beams travel all that way only to hit our eyes when we look up at it. We know that those stars are powerful- like our sun if not more so, yet we see them only as a glimmer. Uninterrupted, the beams will go on forever.
This is the basic idea of the Inverse Square Law. (Yup, more physics) The further away an object is from a light source the more the light will drop in power. So only twinkles from the sky. The image above makes sense of it visually.
How does this affect painting? Well, lets say you are studying a model that has a flood light near them and it is cascading light down on their head. This rule of light means that the top of their head will be more “lit” than the rest of their body. The head is closer to the light source and then the inverse square law takes hold. However, I see paintings all of the time that are copying photos, (or the artist is not paying attention) that show the top of the head, the shoulders and the lap as all having the same strength in power from the light. Same color. Same value. Can’t happen. Its just physics. Because even in a shallow space of only a few feet it takes affect. The skin on the forehead (with this model under a floodlight scenario) will be lighter than the skin on the shoulder and the shoulder will be lighter than the skin on the top of the legs. Light has a “fall off” effect.
The values have to change. The color then has to change. Then the temperature will start to change. In this situation it is all the same local color- the models skin- yet to portray reality accurately it has to shift due to the inverse square law. An essential Rule of light.
If you are not watching for it and aware of it then you may have errors in your work. Thanks for keeping us on track Physics!
I will not be posting a blog over the next few weeks while I am attending my daughters wedding in Antigua. Trust me, I will be studying the light there too….
Hope this helps everyone! Chat soon!