- Sat May 06, 2006 1:47 pm
#150955
Some basic concepts about lighting to understand what we are talking about 
Luminous flux [Φ] Unit of measurement: lumen [lm] Luminous flux [Φ] is all the radiated power emitted by alight source evaluated with the spectral sensitivity of the eye and the photometric his radiation equivalent km.
Luminous intensity Unit of measurement: candela [cd] Generally speaking, a light source emits its luminous flux [Φ] in different directions and at different intensities. The visible radiant intensity in a particular direction is called luminous intensity.
Illuminance [E] Unit of measurement: lux [lx] Illuminance E is the ratio between the luminous flux and the area being illuminated .An illuminance of 1 lx occurs when a luminous flux of1 lm is evenly distributed over an area of 1 m2.
Luminance [L] Unit of measurement: candelas per square metre [cd/m2] The luminance [L] of a light source or an illuminated area is a measure of the brightness.
Luminous efficacy [η] Unit of measurement: lumens per watt [lm/W]. Luminous efficacy [η] indicates the efficiency with which the electrical power consumed is converted into light.
Colour temperature Unit of measurement: Kelvin [K] The colour temperature of a light source is defined in comparison with a “black body radiator” and plotted on what is known as the “Planckian curve”. The higher the temperature of this “black body radiator” the greater the blue component in the spectrum and the smaller the red component. An incandescent lamp with a warm white light, for example, has a colour temperature of 2700 K, whereas a daylight fluorescent lamp has a colour temperature of 6000 K.
Colour appearance The colour appearance of a lamp can be neatly defined in terms of colour temperature. There are three main categories here: Warm White < 3300 K Cool White 3300 to 5000 K Daylight > 5000 K. Despite having the same colour appearance, lamps may have very different colour rendering properties owing to the spectral composition of their light.
Color rendering Index CRI is a unit of measure that defines how well colors are rendered by different illumination conditions in comparison to a standard (i.e. a thermal radiator or daylight). CRI is calculated on a scale from 1-100 where a CRI of 100 would represent that all color samples illuminated by a light source in question, would appear to have the same color as those same samples illuminated by a reference source. To put it another way, low CRI causes colors to appear washed out and perhaps even take on a different hue, and high CRI makes all colors look natural and vibrant.
Some common bulbs
How to set bulb data in Maxwell
In Maxwell we can set the intensity of the emitters with two parameters:
-His color given by RGB, or better, given by his colour temperature in ºK
-His Luminance or luminous flux, given by:
1- Nominal power in W and efficacy in Lumen/W. The Luminous flux is Power(W) X Efficacy (Lm/W) = Luminous flux (Lm)
2- Luminous flux in Lm if we can know this value. When we bought a bulb, usually this data is written in the box: Colour code (not allways colour temperature), Watts, efficacy or Lumen
3- Illuminance in lux. It's a luminoux flux per m2
4- Luminous intensity in Candelas.
5- Luminance in Candelas/m2.
The most common data for emitters is 1 or 2, so the presets are made with these.
We have to think a bit of the right exposure in maxwell cameras to have a good illumination in our scenes.
Common 35mm or digital cameras need to adapt his setting to indoor lighting. Some usual configurations with a room lit with common bulbs (in incandescent bulbs 100W for a 5m2 room, 200-300W for a 10m2 room, 500W for a 25 m2 room) are ISO near 400-800, fStop 4 or 5.6, and Shutter speed near 15-30. Otherwise, we need some aditional light with a flash to take this kind of photos.
The default Maxwell camera settings are ISO 100, fStop 8 and sSpeed 125, very common for outdoor lighting with sunlight
I hope you can understand some of my english. Feel free to ask!
Luminous flux [Φ] Unit of measurement: lumen [lm] Luminous flux [Φ] is all the radiated power emitted by alight source evaluated with the spectral sensitivity of the eye and the photometric his radiation equivalent km.
Luminous intensity Unit of measurement: candela [cd] Generally speaking, a light source emits its luminous flux [Φ] in different directions and at different intensities. The visible radiant intensity in a particular direction is called luminous intensity.
Illuminance [E] Unit of measurement: lux [lx] Illuminance E is the ratio between the luminous flux and the area being illuminated .An illuminance of 1 lx occurs when a luminous flux of1 lm is evenly distributed over an area of 1 m2.
Luminance [L] Unit of measurement: candelas per square metre [cd/m2] The luminance [L] of a light source or an illuminated area is a measure of the brightness.
Luminous efficacy [η] Unit of measurement: lumens per watt [lm/W]. Luminous efficacy [η] indicates the efficiency with which the electrical power consumed is converted into light.
Colour temperature Unit of measurement: Kelvin [K] The colour temperature of a light source is defined in comparison with a “black body radiator” and plotted on what is known as the “Planckian curve”. The higher the temperature of this “black body radiator” the greater the blue component in the spectrum and the smaller the red component. An incandescent lamp with a warm white light, for example, has a colour temperature of 2700 K, whereas a daylight fluorescent lamp has a colour temperature of 6000 K.
Colour appearance The colour appearance of a lamp can be neatly defined in terms of colour temperature. There are three main categories here: Warm White < 3300 K Cool White 3300 to 5000 K Daylight > 5000 K. Despite having the same colour appearance, lamps may have very different colour rendering properties owing to the spectral composition of their light.
Color rendering Index CRI is a unit of measure that defines how well colors are rendered by different illumination conditions in comparison to a standard (i.e. a thermal radiator or daylight). CRI is calculated on a scale from 1-100 where a CRI of 100 would represent that all color samples illuminated by a light source in question, would appear to have the same color as those same samples illuminated by a reference source. To put it another way, low CRI causes colors to appear washed out and perhaps even take on a different hue, and high CRI makes all colors look natural and vibrant.
Some common bulbs
How to set bulb data in Maxwell
In Maxwell we can set the intensity of the emitters with two parameters:
-His color given by RGB, or better, given by his colour temperature in ºK
-His Luminance or luminous flux, given by:
1- Nominal power in W and efficacy in Lumen/W. The Luminous flux is Power(W) X Efficacy (Lm/W) = Luminous flux (Lm)
2- Luminous flux in Lm if we can know this value. When we bought a bulb, usually this data is written in the box: Colour code (not allways colour temperature), Watts, efficacy or Lumen
3- Illuminance in lux. It's a luminoux flux per m2
4- Luminous intensity in Candelas.
5- Luminance in Candelas/m2.
The most common data for emitters is 1 or 2, so the presets are made with these.
We have to think a bit of the right exposure in maxwell cameras to have a good illumination in our scenes.
Common 35mm or digital cameras need to adapt his setting to indoor lighting. Some usual configurations with a room lit with common bulbs (in incandescent bulbs 100W for a 5m2 room, 200-300W for a 10m2 room, 500W for a 25 m2 room) are ISO near 400-800, fStop 4 or 5.6, and Shutter speed near 15-30. Otherwise, we need some aditional light with a flash to take this kind of photos.
The default Maxwell camera settings are ISO 100, fStop 8 and sSpeed 125, very common for outdoor lighting with sunlight
I hope you can understand some of my english. Feel free to ask!
Last edited by jomaga on Sat May 06, 2006 1:56 pm, edited 1 time in total.
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