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)