Lighting Components Flashcards
A layer of light-sensitive cells along the back wall of the eye
Retina
Two types of photo receptors in the retina
Cones
Rods
High-light-level receptors
Cones
Low-light-level receptors
Rods
A flat, colored, ring-shaped membrane behind the cornea of the eye, with an adjustable circular opening (pupil) in the center; kind of like a shutter mechanism
Iris
Protected by the iris from the bright light; a black, circular opening that allows light to pass to retina
Pupil
Adjusting to bright light; daylight vision, vision with sufficient illumination that the cones are active and hue is perceived
Photopic vision
Adjusting to dim light; night vision, the ability to see in reduced illumination (as in moonlight)
Scotopic vision
Three factors that influence the amount of light that will reflect off the object to the eye
Color
Texture
Surface
General type of color, texture, and surface that reflect more off the object to the eye
Light colors
Smooth textures
Shiny surfaces
Initial response and complete adaptation (in minutes) of an eye when shifting from low to high light levels
Less than a minute (initial)
7 to 12 minutes (full)
Complete adaptation (in minutes) of an eye when shifting from high to low levels
20 to 30 minutes
Measurement of illumination or quantity of light falling on a subject
Footcandle (fc)
European measurement of illumination or quantity of light falling on a subject
Lux
Approximate conversion of fc to lux
1 fc = 10.76 lux
Measurement of luminance or quantity of light reflected off the surface of an object; sees by the eye, rather than footcandles, making this measurement more important than footcandles
Footlambert (fl)
The amount of light reflecting off the surface of an object; takes into account the scattering of light as it reflects off a surface
Luminance
The relationship between luminances of an object and it’s background or between two areas in a landscape
Luminance contrast
The amount of light, seen by the eye, reflecting form the surface of an object; takes into account the state of adaptation of the eye
Brightness
A continuum of radiation, including all wavelengths of electric and magnetic radiation; much of the radiation is not seen by the human eye, and the portion that can be seen is called the “visible spectrum”
Electromagnetic spectrum
Basic parts of a lamp
Glass envelope or bulb Filament Electrodes or an arc tube Base Transformer (low-voltage incandescent lamp) Ballast (fluorescent/HID)
Type of glass which cannot withstand physical impact or temperature shock, and does not provide for maximum light output efficiency
Soda-lime or soft glass
Type of glass used for lamps rated for outdoor use in open fixtures; heat resistant and hard
Borosilicate glass
Typical incandescent lamp shape - S, F, G, T, PAR, R, MR, A
Straight side (S) Flame (F) Globular (G) Tubular (T) Parabolic aluminized reflector (PAR) Reflector (R) Multimirror reflector (MR) Arbitrary (A)
Typical HID lamp shape - BT, E, R
Bulbous tubular (BT)
Elliptical (E)
Reflector (R)
The number indicates the diameter of the lamp in eights of an inch at its widest point (ex. what is the measurement of the widest point of an R40?)
A reflector shape 40/8 or 5 inches at its widest point
Part of a lamp that connects it to the fixture socket and provides a path for electricity to reach the filament or arc tube
Base
The wire in an incandescent lamp that actually produces light; it heats up, producing light
Filament
Common material used today for filaments, which combines a high melting point and slow filament evaporation
Tungsten
A coating on the filament tube of some halogen lamps, which allows all the visible light to pass and redirects the infrared radiation back onto the filament
Dichroic coating
Three filament types
Straight (S)
Coiled coil (CC)
Coiled (C)
A filament type where there is more wire and is more closely spaced, which conserves heat and increases both efficacy and filament stability
Coiled filaments
Two basic categories of lamps
Filament lamps
Discharge lamps
Type of lamp that produces light by heating a tungsten filament in a vacuum- or gas-filled envelope
Filament lamps
Composed basically of a sealed glass containing a filament connected at its ends to the contact area in the base thereby completing an electric circuit
Incandescent lamps
Sometimes called quartz lamp, a lamp that offers a more balanced white color, higher efficiency, more compact size, longer life, and higher lumen maintenance than conventional incandescent lamps; have a halogen gas pumped in around the tungsten filament which picks up and redeposits the evaporated tungsten back onto the filament
Tungsten-halogen lamp
Most frequently used incandescent lamps
MR
PAR
R
An incandescent lamp that has a multifaceted-mirrored reflector surrounding a sub-miniature lamp; variations in the reflector permits many beamspread and wattage options in one lamp size; has a compact size which allows the fixture to be small; all are tungsten-halogen lamps, which provide improved color (over standard incandescent lamps); most are low voltage, and these are the ones used primarily for landscape
MR lamps
Type of lamp that creates light by sending an electric arc through a gas between two electrodes; all are more efficient than incandescent lamps at gross light output (lumen production); useful for floodlighting and accent lighting on large-scale commercial projects
Discharge lamps
An electrical device that provides a high-voltage pulse required to start a discharge lamp, then limits the amount of current to the lamp to prevent the lamp from drawing a destructive amount of current
Ballast
Four lamp families of high intensity discharged lamps, lamps that produce light by creating a relatively small electric arc (point sources); each of these lamp types requires a reflector to control its candlepower distribution, and all require an initial warm-up period when turned on, and if power is lost, require a cooling period before restriking their arc
Mercury vapor
Metal halide
High pressure sodium
Low pressure sodium
HID lamp that produce light by passing an electric arc through mercury vapor; produces light predominantly in the blue and green regions of the electromagnetic spectrum, and in the ultraviolet region; produces slightly fewer lumens per watt than the other HID lamps
Mercury vapor
HID lamp that produces light by passing an electric current through mercury gas, and scant quantities of specific combinations of metal halide; offer most balanced white color of all the HID sources; used for outdoor areas where color rendering is important; best choice for promoting plant growth; sensitive to voltage variation
Metal halide
Type of ballast that can aid in controlling color shift, can stabilize life, and prevent unwanted interruptions of light output
Electronic ballast
HID lamp that produces light by passing an electric arc through sodium vapor; produces most of its light in the yellow range of the spectrum. thus its color appears as a golden yellow; typically used only for lighting parking lots and freeways; the color it produces makes plants look dull and lifeless, and creates an eerie atmosphere
High pressure sodium
A lamp not technically grouped with the other discharge lamps; a monochromatic light source producing only yellow light; unable to render any colors well
Low pressure sodium
Consists of a tubular bulb with an electrode sealed into each end, and a combination of mercury (at low pressure) and argon (or a mixture of gases), which help in starting the lamp; the lamp walls are coated with fluorescent powders which are excited by the ultraviolet radiation to produce colors within the spectrum; temperature sensative
Fluorescent lamp
Three kinds of special fluorescent lamps that are used in landscape lighting
Jacketed
Aperture
Reflector types
A fluorescent lamp designed for low temperature operation
Jacketed (J)