Three-point lights |
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Three-Point Lighting
Key Light
Used as the main illumination and defines the main angle of the lights. This light will have the highest intensity of the three lights and casts the darkest shadows.
This light should never be centered on the object of focus. A better position would be to offset the light from the center and raise it up above the head.
Using a lower position, lower than the head, can create an unnatural appearance in illuminating the face.
Using a high position, almost straight down, can create the appearance of sunken eyes or more commonly known as “raccoon eyes”.
Positioning the key light behind the figure will highlight the profile which gives a heavier sense of the scene.
The key light is typically positioned 15-45 degrees relative to the camera. If you are planning to create a profile of the figure, the key light is usually 80-120 degrees center of the camera.
Fill Light
Softens and extends the illumination of the key light. This light can also simulate the effect of reflected light from other objects in the scene.
The fill light is dimmer than the key light and usually in opposite position of the key light. This usually simulates indirect illumination.
As a general loose guideline, the fill light should be 15-60 degrees left or right of the camera. With the same rule, the fill light should be 0-30 degrees above the camera in ‘normal’ lighting situations.
Another general loose guideline for placement of the fill light to direct it in the general direction of the bounce light from the nearby wall.
Third general guideline: when the key light is high, the fill light should be low.
Key-to-Fill Ratios
One of the important factors for using fill lights is to keep a proper ratio of fill to key light to maintain a good tonal and contrast balance. Too much fill light can compete with the key light and too little fill will leave the dark side undefined. Key-to-fill ratios measures are meant to maintain the scene’s contrast level.
Do not confuse high-key and low-key with key-to-fill terms. High-key and low-key describe the level of overall brightness in the scene, not the intensities of the individual lights.
Key-to-fill ratios are expressed in numbers values as 3:1, 2:1, 10:1 as for example. The first number of the ratio divides the intensity of the fill light. Example: if the ratio is 4:1, then the intensity of the key light is 100% and the fill light intensity is 25%.
Low Key-to-Fill
White highly reflective interiors naturally have a low key-to-fill ratio.
Cloudy, overcast or any other lighting situation that blocks direct sunlight produces more scattered light which in turn will create a very low key-to-fill ratio.
Using low key-to-fill ratios also help lighten the mood or make it appear happier.
If your output will end up in print or film, a low key-to-fill ration is preferred. Standard televisions have a harder time displaying the full range of tones.
Don’t allow the fill light to have a ratio lower than 2:1. At this point, the fill light will be competing for the main point of light source.
- If you are using multiple fill lights, make sure the total
of the fills don’t upset the key-to-fill ratio balances.
High Key-to-Fill
For more dramatic lighting situations, use higher key-to-fill ratios such as 8:1 or more. High key-to-fill ratios will have a darker shadow and high contrast between light and dark areas.
Nighttime have high key-to-fill ratios. Consider your light sources: either moon light or an artificial light but either way, there won’t be any fill light from the sky.
Film noir use little or not fill light to obtain its dramatic and suspenseful scenes.
When rendering for film, use a key-to-fill ratio of 8:1 to get a greater sense of brightness. If you are rendering for television, use a ratio of 16:1.
Although high key-to-fill ratios are more attention grabbing, don’t assume that this lighting scheme is better. Use your artistic license to determine which lighting setup works best for your scene.
Backlight
Backlight is also known as rim light because it is often used to highlight the rim of the surface it is illuminating.
This light defines the edge of the figure. Often, this light will be used to highlight the hair and shoulders.
Don’t confuse the backlight with background light. The background light is used to illuminate the background elements in the scene.
Backlighting has its roots in black and white film. To draw the actors away from the gray backdrops, a light would be placed behind the actors.
Often, backlighting is unnecessary if you have low key-to-fill ratios.
Sometimes, it is okay for your backlight to be brighter than the key light. Because this light is going to be used to highlight the rim of the surface, the angle of the backlight will only illuminate a small portion of the surface that will be visible to the camera.
The backlight is usually placed directly opposite of the camera. If you do place the backlight directly opposite of the camera, be careful with the light’s intensity. More often than not, this backlight position will have blocked lighting to some or all the surface you are trying to backlight. To gain better control, offset the backlight’s position so that it doesn’t sit exactly 180 degrees of the camera.
There is not specific formula to using backlighting. Use as many lights as you need to obtain the backlit look and position as needed to illuminate the rim of the surface.
General Rules About CG Lighting
Symmetrical lighting positions tend to be unnatural.
Don’t let your models lose visual value by being poorly lit. Model your surfaces with light!
Three-point lighting is a flexible guideline. Be ready to experiment!