Spring 2012 Studio: Lighting Lecture One
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Light and Optical Properties
How light is effected by materials and surfaces
What all light sources have in common
Ways to control light
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Light Fixture
Electric Sources
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LampBulb
Electric Sources
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Wiring Basics
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Basic Wiring
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Basic Wiring
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What Makes Light: The Sun
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What Makes Light: Fire
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What Makes Light: Electric Sources
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Points
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Blobs
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Lines
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Optical Properties of Light
Light Travels in a Straight Line Light Bounces and Reflects Light Refracts and Bends Light is Comprised of Many Colors
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Sunlight
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Sunlight
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Projected Patterns of Light
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Sun Angle
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Light Direction
Light travels in a straight line…radiates out from the source
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Light Direction of Clear Lamps
Light travels in a straight line…radiates out from the source
…. add a clear enclosure or envelope around the source, the light will still travel in a straight line.
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Projected Patterns of Light
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Shadows
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Kumi Yamashita
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Fabrizio Corneli
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Larry Kagan
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James Turrell “Wedgework”
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James Turrell “Wedgework”
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James Turrell
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Projections
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Light in Art
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Light in Art
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Shadow Terminology
Shading
Attached Shadow
Inter-reflection
Cast Shadow
Penumbra
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Light Direction
Light travels in a straight line…radiates out from the source
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A Shadows Penumbra
Small light source
Full Light
100%
0%
No light
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Light Direction of Frosted Lamps
Light travels in a straight line…radiates out from the source
…. add a coated or frosted enclosure or envelope around the source, the direction of light will bend and radiate from the surface of the enclosure
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A Shadows Penumbra
Large light source
Full Light
100%
0%
No light
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Steven Holl Architects
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Shadows in Science
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Shadows Teach Us
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Shadows Teach Us
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Shadow Recognition (identification)
We see a shadow, then activate a recognition process that triggers the category of the object
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Shadow Recognition (identification)
We see a shadow, then activate a recognition process that triggers the category of the object
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Shadows Proofs
Typically shadows hide. But, a shadows can also reveal. In this case, the round shadow cast from some object out of view can sharpen the contrast of the small shadow , and make it more visible.
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Losing Shadows
The image of a face is seen on the left – shadows reveal the contour,But, outline the shadow, and the effect is lost.
The outlining turns the shadow into a non-shadow, and prevents vision from using it to reconstruct the 3-D structure of object.
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Famous Shadows
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Famous Shadows
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Famous Shadows
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Famous Shadows
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Grazing Effect
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Reflected Light
Optics Absorption Reflection Light
100%
80% 80%
The material absorbs 20% - reflects 80%
Typical Materials:MetalMirrorWood
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Reflection
For “specular” reflectors, the angle of incidence equals the angle of reflection
Light Source
Incidence
Reflection = the light that exitsIncidence = the light that enters
Reflectance
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Reflected Light Luminaires can shape light by
reflection Reflectors finishes may be
Specular – shiny, polished Semi-Specular Diffuse – dull, matte
Light Source
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Julio Le Parc
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Dan Graham
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Reflected Light Luminaires can shape light
by reflection Reflectors may be
Specular – shiny, polished Semi-Specular Diffuse – dull, matte
Light Source
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Uršula Berlot
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Joost van Santen
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Joost van Santen
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Joost van Santen
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Reflector Contours
Parabolic
Reflection Rays are Parallel
Parabola or Parabolic Reflector
Typically Specular Finish
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Reflector Contours
Ellipsoidal
Rays converge
2 foci
Ellipse, Ellipsoidal, or Elliptical Reflector
Typically Specular Finish
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ReflectionRays are Parallel
Parabola or Parabolic Reflector
Typically Specular Finish
Rays converge
2 fociEllipse, Ellipsoidal, or Elliptical Reflector
Typically Specular Finish
Reflector Contours
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Refracted Light
Optics Absorption Transmission
Light100%
80% 80%
The material absorbs 20% - transmits 80%
Typical Materials:GlassPlasticFabric
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Optical Lenses
Plano-Convex: diverging rays are refracted to make a parallel beam
Fresnel: Flattened Plano-Conex lens
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Refraction
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Refraction
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Refracted Light
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Controlling Light
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What is Light?
Light is a form of energy that is part of the electromagnetic spectrum visible to the human eye.
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Light = Color
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Light = Color
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Light = Color
Colors by AdditionMixture of Light
Colors by SubtractionMixture of Pigments
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Color Mixing
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What is Light?
There are two different ways of talking about light:
There is the "particle" theory, expressed in part by the word photon.
There is the "wave" theory, expressed by the term light wave.
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Light = Energy Waves
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Light = Color
Spectral Power Distribution Curves (SPD) provide the user with a visual profile of the color characteristics of a light source. They show the radiant power emitted by the source at each wavelength or band of wavelengths over the visible region (380 to 760 nm).
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Color Spectrum
Incandescent Lamps and Natural Daylight produce smooth, continuous spectra.
Night Morning Afternoon Late Afternoon Night
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Passenger(stills), video projection, 2004Jutta Strohmaier
For Passenger, Strohmaier photographed the same spot every minute for three days. “The private, insular room opens up to the outside world under certain light conditions, blurring the boundaries between the inner and outer worlds,” she explains. “It’s like looking out the window of an airplane – time and space pass by.”
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Color Spectrum
Fluorescent Lamps produce a combined spectrum… a non-continuous or broad spectra with gaps from their phosphor, plus UV from the mercury discharge.
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Light = Color
Daylight at Noon Afternoon Sun
Candle
Full Moon
Incandescent CompactFluorescent
TubularFluorescent
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Metal Halide High Pressure Sodium
PC Laptop
PC Monitor(indigo nightlight)
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High CRI light makes virtually all colors look natural and vibrant.
Low CRI causes some colors to appear washed out or even take on a completely different hue.
Color Rendering Indexhow a light source renders the color of objects
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Rufus Knightwebb
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Dan Flavin
Light sculptures that illuminate space around them. They inhabit space. They bathe space -and visitors - in a warm and completely artificial glow
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Dan Flavin
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Dan Flavin
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Dan Flavin
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http://www.gelighting.com/na/business_lighting/education_resources/learn_about_light/color_lamp.htm
Seeing Color
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The higher the color temperature (CCT), the “cooler” the color of the lamp is in appearance.
2700 o 4100 o2200 o
The lower the color temperature (CCT) the “warmer” the color the lamp is in appearance.
This color temperature is measured in Kelvin.
Correlated Color Temperaturecolor appearance of various light sources
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9000850080007500700065006000550050004500400035003000250020001500
Kelvin TemperatureCool
Warm
North Blue Sky
Direct Sunlight
Overcast Day
Fire / Candle light
Hot Embers
HalogenIncandescent
Mercury
High Pressure Sodium
Metal Halide
3000K Metal Halide
Daylight FluorescentCool White Fluorescent
4100K Fluorescent
3500K Fluourescent3000K Fluorescent
Warm White Fluorescent
Correlated Color Temperature
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Correlated Color Temperaturecolor appearance of various light sources
5000 deg Kelvin 4000 deg Kelvin 3000 deg Kelvin
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Color Rendering Indexhow a light source renders the color of objects
The color rendering of a light source is an indicator for its ability of realistically reproduce the color of an object.
Following the CIE (International Lighting Commission), color rendering is given as an index between 0 and 100, where lower values indicate poor color rendering and higher ones good color rendering.
The color rendering of a light source is compared a continuous spectrum source, such as incandescent - to daylight if its CCT is >5000K.
Comparing the colour appearance under different light sources (left);Test swatches under different light (right)