Lighting: Supplementary Lighting System from Eye Lighting
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Understanding CRI

What does CRI tell us? CRI tells us how accurately a light source displays specific colors. They are listed below.

cri test colors

If a light source displays these 14 colors perfectly the corresponding CRI would equal 100.  If the light source did not display any color correctly its CRI would be 0 (zero).

Why was the CRI index created?  To help companies sell product!  As an example, if a light source does not accurately display colors, the carpet that you purchased in the store may look completely different at home.  A red shirt may look orange or pink.  A white car may look grey or creamy.

Do your plants care about CRI?  Only if they are buying carpet, shirts, or cars.

Some horticulture lighting brands publish the CRI values.  However, CRI value has little to do with lamp spectrum or its ability to grow plants.

The Color Rendering Index (CRI) is a rating system that measures the accuracy of how well a light source makes colors of an object look.

R9 or strong red is one of 14 test colors used to calculate a color rendering index. The higher the R9 number, the more accurate and vivid the illumination (perceived color of the object).

Since some percentage of the color Red can be found mixed into the various hues of most processed colors, the ability to accurately reproduce Red is key for accurately rendering colors of displayed objects.

Lamps with high R9 values produce the most vivid colors.

Color Rendering Characteristics of Common Light Source Lamps

Lamp CCT (Kelvin) Ra (CRI) R9
Metal Halide 4220 67 -113
High Pressure Sodium 2100 21 -197

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EYE HORTILUX® offers grow lamps and ballast for indoor gardening applications. Our grow lamps are made in the U.S.A.

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