FAQs
LED is the abbreviation for “Light Emitting Diode”. This is a semiconductor device that emits light when direct current flows through it. The color of the generated light depends on the structure of the LED chip and the materials used. LEDs are temperature-sensitive dimmable point light sources that emit their light with hemispherical distribution towards the front.
Lumen measures brightness & watt measures consumption of energy or electricity (power).
Candela Represented by the symbol l (cd) Unit of → luminous intensity, the basic unit of measure in lighting technology. 1 cd is defined as the luminous intensity emitted by a monochromatic light source with a radiant power of 1/683 W at 555 nm at a solid angle of 1 steradian
The Quality of the reproduction of colors under a given light. The degree of color distortion in comparison with a reference light source is classified by the color rendering index Ra, or by the color rendering category
The SDCM (Standard Deviation of Colour Matching) value describes the colour consistency (colour location deviation) of light sources using the MacAdam ellipses as defined by David MacAdam.
Illuminance Represented by the symbol E (lx) Illuminance is defined as the ratio of the amount of luminous flux falling, represented by the symbol L (cd/m2) Luminance describes the brightness of a luminous surface which either emits light through auto luminance (as a light source), → transmission or → reflection. The luminance is accordingly defined as the ratio of → luminous intensity to the area on a plane at right angles to the direction of beam
Luminous efficacy describes the luminous flux of a lamp in relation to its power consumption, (lm/W).
It is Represented by the symbol (lm) Luminous flux describes the total amount of light emitted by a light source.
Luminous intensity Represented by the symbol l (cd) Luminous intensity is the amount of lumi- nous flux radiating in a given direction (lm/sr).
Photometry is a measuring method to determine photometric quantities.
The human eye is the visual organ processing the incoming light stimuli of the environment.
Angle of view Angle at which an object under view is perceived, measure for the size of the image of the object on the → retina & the Beam Spread is the angle between the limits from which the axial value of a → light intensity distribution curve decreases to 50%. The beam spread is the basis for calculating the diameter of light beams emitted by symmetrical luminaires
Ambient light provides general lighting of the visual environment. Architecture, objects and people in the environment are visible, which allows orientation, work and communication
Generic term to describe the depreciation of → visual performance or the disturbance felt by perceivers through excessive → luminance levels or → luminance contrasts in a visual environment. A distinction is made between disability glare, which does not depend on luminance contrast, and contrast related relative glare
The Light source has a colour temperature which will dictate whether the light emitted is either of a warm colour, an intermediate or neutral color, a cool colour or a cold colour. The higher the color temperature, the cooler white, the color appearance of the light source. The Color Temperature is a description of the warmth or coolness of a light source. It is most simply, a method of demonstrating the color characteristics of light, usually either as warm (yellowish) color or a cool (bluish) color.
To adjust the light output as per the scene or place, the beam angle is the point at which the light output Lumens drop below 50% of the total light output. LED beam angles typically vary between 10° – 120°. The beam angle is the area where the light is at its most intense.
All light sources degrade over time. LM80 is the method for measuring how much lumen depreciation the light source will suffer. This is not to be confused with an estimation of life. LED’s typically do not fail as they have no filament to burn to end their life, rather degrade beyond useful life output.