# CFL's - Lumens vs. CRI rating



## triprey (Jul 27, 2007)

OK here is a question for all of you lighting experts. I know that HPS is the best way to go, so I do not need info on that in this thread. I will get their when I can. That being said, I have looked all over this forum and have not found the answer to this one yet. When getting a CFL, do you think it is more important to get more lumens or a higher Color Rendering Index (CRI) rating?:confused2: 

For example:

Between these two choices for the veg stage, which do you think would be better.


Choice #1
Energy Used 26 Watts
(hr) 10,000 Light 
Output 1,700 Lumens 
Finish Bright White CRI 82
Color Temperature (Kelvin)5000K

Choice #2
Energy Used 24 Watts
(hr) 8,000 Light
Output 1,650 Lumens
Finish Bright White CRI 85
Color Temperature (Kelvin)5000K


The first one has more lumens and wattage used, but not as much CRI, the second one has less lumens and less wattage used, but more CRI.

So what do you think gang, pay for more watts to get the lumens or less watts for higher CRI?:headbang:


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## DLtoker (Jul 27, 2007)

CRI isn't all that important... What really matters is the color temp when it comes to growing.  If I were to choose one of these bulbs, I would choose the 24W bulb because it puts out more lumen per watt.


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## Bubby (Jul 27, 2007)

A quick google: http://www.sizes.com/units/CRI.htm



> A figure of merit, on a scale of 0 to 100, used by manufacturers of fluorescent, metal halide and other nonincandescent lighting equipment to *describe the visual effect of the light on colored surfaces*. Natural daylight and any light source approximating a blackbody source (see color temperature) is assigned a color rendering index (CRI) of 100.
> 
> To determine a CRI value, observers view 8 standard pastel colors under the light source being rated and under light from a blackbody source (such as an incandescent lamp) having the same color temperature. The CRI is calculated, roughly speaking, by averaging the observers' estimation of the extent of the differences in the appearance of the colors under the two lights. Although the *CRI is intended to apply only to the visual quality of light*, photographers have also used it in choosing light sources.
> 
> The CRI can only be used to compare two light sources that have the same color temperature. A 5000 K, 80 CRI light source is not necessarily superior to a 4000 K, 70 CRI light source.



Can we conclude CRI isn't useful to know?


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