Reflected light is light that comes from a source other than the primary light source. When you’re talking about art and drawing or painting, reflected light is the light that bounces off something else and strikes whatever object you’re painting.
No matter what subjects you draw or paint or how you draw or paint them, what you’re really working with is light.
The most noticeable light is direct light, whether from an artificial source or a natural source. But that’s not the only type of light.
Inanimate Objects and Reflected Light
Here are a few reference books. A natural light source (the sun) in an outdoor setting, illuminates the books and their surroundings.
The light source is from the upper right and almost directly to the right of the books, so if you could see highlights, you’d see them on the front covers.
The Merck Manual is getting the most direct light, but since the brightest light is on a side that isn’t visible, you can’t see the brightest highlights anywhere but along the edge where the spine curves around to meet the front cover.
But there is plenty of reflected light.
Take a look at the edges of the pages on the top most book lying on its side immediately to the right of the Merck Manual. Light is bouncing off the cover of the Merck Manual onto that edge. The two books are close enough to each other and the light is intense enough that not only does it light the edges of the pages; it tints them red.
If the light source is strong enough and the object off which light is being reflected is close enough to the object onto which light is being reflected, the second object will reflect color as well as light.
Now look at the other side of the Merck Manual. See the strip of light on the left side of the spine? That is light bouncing onto the Merck Manual after striking the middle book. It’s much dimmer than the reflected light on the horizontal books because the source light is less intense. The two surfaces are also further apart.
The angle between the two books is also different. They are closer together at the top than at the bottom, so the reflected light on the Merck Manual is strongest at the top (where the two books are closest together) and fades away completely at the bottom (where the books are furthest apart).
The bricks are also illuminated by reflected light from two directions: Red-tinted light from the cover of the Merck Manual and orange-tinted light from below off the orange book.
Reflected Light and Horses
Reflected light affects more than smooth or shiny objects. It affects all subjects, animate and inanimate. Take a look at this photo, for example.
This horse is well lighted, with strong sunlight from the upper right of the image. The cast shadow is directly beneath the horse and stretches out behind. The shadows are all exactly where you expect them to be.
But note that his belly and the downward facing planes of the chest are light. The darkest part of the shadows is not on those surfaces but partway up the horse’s side and chest.
The light areas light bouncing off the sandy ground and illuminating the underside of the horse. The affect is especially noticeable because the primary light source is very strong, the horse’s coat is smooth, and the ground is flat, bare, and reflective.
If the horse was also wet, the reflected light would be more noticeable.
If the primary light source was dimmer (as in a cloudy day or indoor light), if the horse had longer hair, or if the ground was covered with grass or mud, there would be less reflected light on the horse’s undersides.
Also take a look at the top slope of the horse’s rump. Note that it’s well lighted even though that part of the horse doesn’t face directly toward the light source. Compare it to the shadow on the ground.
The light across the top of the rump is another form of reflected light. This time, the light being reflected is from the sky, hence the bluish tint.
Not drawing or painting reflected won’t make your art bad. I painted portraits for years without understanding or using reflected light.
But a good understanding of how reflected light functions and knowing how to draw or paint it will make the subjects you paint or draw look more three-dimensional. It is a valuable addition in your art toolbox no matter what your preferred subject.