Here everything is clear without words.
In this short video story clearly shows the difference in the light of sodium lamps with HPS 400W, by issuing 48,000 lux meter readings Lm and induction lamp induction lamp with a power of 250W, outstanding on the testimony of 20 lux meter 000Lm. Here one can see very clearly the difference between the brightness of recorded modern appliances — Light meters and the apparent brightness, measured in lumens effective PLum.
When replacing old lighting induction, people are faced with an interesting fact, the new induction lights shine for many visually brighter than the light meter says about it. What's the matter? Scientists have figured out in this matter, and to facilitate the selection of induction lighting introduced a new concept — "visually effective lumens."
All luxmeters filters, lighting, filling lamps, phosphors compounds are produced and adjusted according to the color model CIE XYZ, this model shows the human eye to perceive color
The model was developed by the International Commission on Illumination in 1931, bearded and corrected, not less bearded, 1964. Since then, she has not changed. However, science has stepped forward, and the study of human ocular apparatus show that things are different.
Anatomy of a school course we remember what we see through the special cells found in the retina of our eyes, it's the rods and cones. Contrary to popular belief, night vision (black and white), which is responsible for the sticks, will not turn off during the day. At full expansion of the rhodopsin in the cells, night vision shifts to the blue part of the spectrum. This property of our eyes have not considered in the construction of color model, and a new color model — it is long and expensive. It is also associated with this well-known effect, the effect of the Purkinje
How do we calculate the coverage if lux meter readings do not reflect the whole picture objectively? In this matter, we were helped by Dr. Francis Rubinstein of the Department of Building Technology, National Laboratory. Lawrence Berkeley, California. Kindly give us the measurements lux meter is configured on the color model of twilight. These values were used to obtain the coefficient of S / P.Koeffitsient S / P ratio is a measurement suite meters corrected for the color curve daylight to measurement suite meter is configured on the night of the curve. Take an ordinary light meter, measure and multiply this value by this factor. While the International Commission did not carry out a new investigation, we will use yet, this coefficient.
Below is a table of conversion factors in light of indications Lm (lumens) in a visually effective lumens (PLm).
|Type of light source||S / P ratio|
|Induction lamp 6500K||2.22|
|Metal halide lamp||1.49|
|Lum. Lamp "warm white"||1|
|High pressure mercury lamp||0.8|
|Low Pressure Sodium||0.35|