Drawing and painting fire lit scenes is a difficult challenge for most aspiring artists. I remember struggling with it — mixing all sorts of warm colors, using white for the hot spots, but never quite getting it right. I admit it is still tricky to this day, but knowing the basic principles takes away most of the confusion. Although we are discussing firelight in this article, the majority of concepts can be translated to any kind of point-source illumination. For instance fantasy light orbs or any sort of sci-fi light effects.
Back in the days before electricity people lit their candles at dusk while they could still see enough to find the matches. Artists were a lot more familiar with fire lit scenes since it was their main source of light. I believe our alienation from firelight stems from the fact that we were born and raised in an electricity powered society and while firelight still has a psychological effect on us, we get in contact with fire on very rare occasions. Most of us are not exposed enough to those circumstances in order to pay attention to the visual details and principles. This is why almost every single time artists use photographic reference when painting fire or fire lit scenes. Cameras however, do not replicate the world exactly how the human eye sees it. There are important details lost that makes an image truly sing with emotion.
Firelight is a Yellow-Orange weak light. You can notice its true power only once the sun starts to move below the horizon. It is a very frequent mistake to make fire light stronger than it really is. Furthermore, its tonal value is significantly darker than usually depicted in amateur art. If we are to define it on a 12 step value scale with 12 being the absolute black, firelight would be around 5 to 4.5 — with 2 being the highest tones in the fire itself. Another very common mistake is depicting the fire lit object with overly high tonal values, or even going as far as starting the gradation with white followed by the colors of the light source.
Firelight creates a warm halo around itself making it impossible to see details around and beyond it. This is good to keep in mind even when using photo manipulating techniques; the details around and beyond the source are best removed.
Smoke often scatters the light and fills the neighboring darks with a warm glow creating many smooth edges. There are no deep darks around the light source. When working from photographic reference one might see the darks much deeper than they actually are — but don’t be misled, to the eye the shadows around the source do not appear black and they often seem to have a warm glow.
The brightness of a light source diminishes rapidly with distance. Artists often call this weakening of light Fall-Off.
Inverse Square Law
According to the inverse square law, the effect of a light shining on a surface weakens at a rate comparable to the square of the distance between the source and the surface. This law is used in several areas of science, not only to describe the behavior of light but also the pull of gravity, the push-pull of charged particles and the intensity of sound.
The above diagram shows how at twice a distance the light is only one fourth as bright, because the same rays have to cover four times the area; and at three times the distance the intensity drops to one ninth of the initial.
Maybe this seems a bit too technical for some, but once you get the idea it is really simple stuff. Again, just to summarize:
- Firelight is a weak light
- Firelight does not have a high tonal value. Do not use white or bright yellow on matt surfaces when illustrating fire lit objects.
- You cannot see through the halo of the light source. Do not show details in the vicinity of the flame or source.
- Darks are not black around the light source. They glow with warm light and have mostly soft edges.
- The brightness of firelight diminishes rapidly with distance.
- Using the inverse square law you can calculate the intensity of light.
Next time you go out camping or find yourself around a fireplace make sure you pay attention to how firelight really works and try to find these ideas at work in the environment around you.
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