Controllable Properties of Light

Four controllable properties of Light:
	- Intensity
	- Distribution
	- Color
	- Movement

INTENSITY: brightness of the light.
	Affected by:
	- Brightness of the source
	- Distance of the source, inverse square law

Inverse square law
	Light emitted in all directions, spreading over ever-larger area.

	Illumination decreases as the square of the distance

Measuring Intensity:
Candela: once called candle-power.  Light from one candle measured 
	at one foot on the inside of a sphere (12.57 sq. ft.)

Lumen: amount of illumination produced by one candela on one square ft. 
	at a distance of one foot.

Foot-candle: brightness of a standard candle on one sq.ft. at one foot.

One LUMEN per SQUARE FT. is therefore one FOOT-CANDLE.


Lets put these together.

Assume a source producing 48 candela.
	48 candela = fc x dist. sq.
	48 cand/1 sq.= 48 foot-candles at 2 ft.:
	48 cand/2 sq.) = 48/4 = 12 ft.-candles at 4 ft.:
	48 cand/4 sq) = 48/16 = 3 ft.-candles

Therefore, how far your lights are from the stage will have a 
	large effect on how bright they are.

Brightness a "relative" term.
We judge brightness in context.  
	Single spot in darkness looks brilliant.
	Same spot in a wash may be unnoticed.

Brightness can also be varied by dimmers.


DISTRIBUTION:
Ddirections light comes from.
	Front light-  enhanses visibility
	Side light-  enhances plasticity
	Back light and rim light:  separates the actor from background.
	Top light-  similar but less effective than back lighting.
	"McCandless"  45-45 blending of the front and side light; 
		visibiltiy and plasticity with a minimum of equipment.

COLOR:
The color of the lights.  
Usually achieved with  color media.  
Usually used in combinations, moving towards white.

MOVEMENT:  Illuminate different parts of the stage in turn.  
Makes the audience look where you want them to.  
	Obvious: follow spots or wiggle lights
	Subtle; crossfading from one look to the next.