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Characteristics of Light

Intensity-(How bright the light is)

Color
•The color of reflected light is dependant upon the color of the surface from which it is reflected.
•Time of day affects color: early morning and late afternoon the color of light is warmer than during mid-day.

Quality
•Hard light (direct light with defined shadows)
•Soft light (diffused or bounced light with soft edge shadows)

Direction
•Where the light comes from
•Angle of the light (high or low)

Intensity

The Inverse Square Law:
An object twice the distance from the light source will receive a quarter the amount of illumination.


This diagram shows how the law works. The lines represent the flux emanating from the source. The total number of flux lines depends on the strength of the source and is constant with increasing distance. A greater density of flux lines (lines per unit area) means a stronger field. The density of flux lines is inversely proportional to the square of the distance from the source because the surface area of a sphere increases with the square of the radius. Thus the strength of the field is inversely proportional to the square of the distance from the source.
Standing 3 feet away. Subject is shot at key.
Standing 6 feet away. Subject is 2 stops under exposed as only 1/4 the amount of light is now reaching him.
Standing 6 feet away. Exposure compensated 2 stops.

Two subjects, one illuminated more than the other. How to fix this?

If possible move the subjects away from the light or the light further back.
Color

Electro Magnetic Spectrum

Visible Light
Reflected Light

Hard and Soft Light


Hard Light
Soft Light
Softer Light
 

White Balance

Most light sources are not 100% pure white but have a certain "color temperature”. For instance, the midday sunlight will be much closer to white than the more yellow early morning or late afternoon sunlight.
Normally our eyes compensate for lighting conditions with different color temperatures. A digital camera needs to find a reference point, which represents white. It will then calculate all the other colors based on this white point. For instance, if a halogen light illuminates a white wall, the wall will have a yellow cast, while in fact it should be white. So if the camera knows the wall is supposed to be white, it will then compensate all the other colors in the scene accordingly.

Most digital cameras feature automatic white balance whereby the camera looks at the overall color of the image and calculates the best-fit white balance. However these systems are often fooled especially if the scene is dominated by one color, say green, or if there is no natural white present in the scene.

Most digital cameras also allow you to choose a white balance manually, typically sunlight, cloudy, fluorescent, incandescent etc. Prosumer and SLR digital cameras allow you to define your own white balance reference. Before making the actual shot, you can focus at an area in the scene, which should be white or neutral gray, or at a white or gray target card. The camera will then use this reference when making the actual shot.

Daylight White Balance
Shade White Balance

Tungsten White Balance
Fluorescent White Balance

 
Here you can see that the color and quality of light changes during the day

 

Direction
3/4 Frontal Lighting or Rembrandt lighting
Frontal Lighting or Butterfly Lighting
Under Lighting
Side Lighting
Back Lighting
Top Lighting
These images illustrate the use of multiple lights in several directions used to bring out the three dimensional qualities of a subject. This formulaic lighting is called Three Point lighting.
Qualities of Natural Light
Sunny afternoon
Midday sunshine
Late afternoon/early evening
Sunset
Dusk
Open Shade
Overcast
Bright overcast
Broken cloud, stormy light, dappled light
Night


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