Module 2B - Properties and Quality of Light

Cameras reproduce colors by adding values of red, green, and blue (RGB).
Daylight is white light, typically measured around $5500 K°$ . Represented by the sun icon on cameras.
Color perception results from light reflecting off a surface.
Under white light, a white sheet of paper appears white.

Every light source has its own color value (e.g., candlelight at $1000K$ , shade at $10000K$ ).
Photographers must be aware of how a light's color value impacts recorded colors.
Light sources at $2800K$ produce warmer (orange/yellow) light.
Brains try to interpret colors as known, but cameras record actual reflected light.
A white sheet of paper under $2800K$ light appears orange/yellow in a photo if the camera is set to daylight white balance.
To correct the color, adjust the white balance setting to match the light source (e.g., the light bulb icon for tungsten light).
Cameras with a Kelvin option allow setting the white balance numerically (e.g., $2800K$ ).
Color temperatures range from $1,000$ to $10,000K$ .
Kelvin white balance options typically range from $2200K$ to $10000K$ in $100K$ increments, offering 79 distinctive options.
White balance icons are less precise than using the Kelvin setting.

Accurate color is often important for commercial work.
It can also be vital for capturing specific hues, like the subtle warmth of an off-white wedding dress.

Photographers may intentionally shift colors for artistic effect.
Examples: Warmer skin tones, cooler tones in snow scenes, warmer tones in summer scenes.

The angle at which light strikes a surface equals the angle of reflectance.
Normal is the line between the camera and the subject.
If the light source is behind the camera, the angle of incidence is $0°$ . At a $45°$ angle, the angle of incidence and reflectance are both $45°$ .
Glossy surfaces reflect more light than matte surfaces.
Reflected light takes on the color of the reflecting surface.

The size of the light source relative to the subject determines hardness or softness.
It affects the size and intensity of highlights and the hardness of shadows.
Smaller light sources create specular highlights and hard transitions between highlight and shadow.
Larger light sources create diffused highlights and softer transitions.
Example: strong specular highlights from a small portable flash versus diffused highlights from a softbox.

States that the intensity of light on a subject is inversely proportional to the square of the distance from the light source.
Doubling the distance loses two stops of light.
Halving the distance gains two stops of light.
Formula: If distance is doubled (2X), intensity is reduced to 1/4 (two stops): $(1/2)^2 = 1/4$
Example: Light measures F11 at 10 feet, it will measure F5.6 at 20 feet.
If distance is halved (1/2X), intensity is increased by a factor of 4 (two stops): $2^2 = 4$
Example: Light measures F11 at 10 feet, it will measure F22 at 5 feet.

Light falls off more rapidly at closer distances.
Depth of light describes the consistency of exposure and the rate of falloff.
To light a 15-foot car: A softbox at 5 feet from the front may result in F16 at the front bumper and F4 at the rear.
Moving the light back to 15 feet from the front reduces the falloff (e.g., F16 at the front, two stops less at the rear).
The further the light, the slower the falloff. The closer the light, the quicker the falloff.