SkyHarvest

I just spent 8 hours doing nothing but smoking cigarettes, drinking coffee and reading about every type of light mentioned on this site as well as the subject of light its self. People are equating the high lumen output of the HPS as meaning the HPS puts out more "power" or "energy" overall. This might not be so true. Lumens as a unit of measurement is based on the area of the spectrum that the human eye sees best: yellows. HPS simply pumps out more yellow light than anything else.

Check it out:

Quote:
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Sodium Lamps
Figure 4 shows the spectral power distribution of a typical HPS lamp, drawn to the same wavelength scale as the photopic eye-sensitivity curve. The reason for the high lumen output of the HPS lamp immediately becomes apparent. The maximum energy output of sodium lies in a yellow region where the eye sensitivity is very high.

Because the lumen is defined as the amount of light perceived by the eye under photopic conditions (the 'light adjusted eye' curve in Figure 3), HPS lamps have high lumen ratings. It is not so much that the sodium lamp produces a high output of energy but rather its energy peak is near the maximum photopic sensitivity wavelength of the eye.

Note that very little energy output of the HPS lamp occurs at wavelengths shorter than the peak. Therefore the effective lumens for scotopic conditions (the 'dark adjusted eye' curve in figure 3) is greatly reduced. Sodium produces very little blue and green light and therefore its effectiveness under low light levels is considerably reduced.
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I can give the link to the rest of the article to anyone who wants it, I just don't want to put a direct link here.

I also found two spectral power distribution charts...if anyone wants the links, I'll be happy to provide them.

One is for HPS and the other is for generic full spectrum floros. The HPS peters out below 100 (relative energy) at around 650 nm- right where orange turns to red. Thats why light from an HPS can make red things look orange. The generic full spectrum floro is 390 (relative power) at 650nm at which point it begins a slow downward curve, maintaining a relative power of at least 200 up to 700nm where it dips to 190 and continues its decline but never going beneath 100 until it is at 800-nm, well into the violet end of the spectrum. In other words, once into the red, full spectrum floros are always at least 100 relative energy more than HPS.

I gather that HPS has a kelvin of around 200 because it blows so much energy (peaks) through the mid-high spectrum (yellow/starting orange- all those lumens) and has little to offer in the low-mid spectrum (450-500). On the other hand the floros have such a high kelvin (over 500) because for One they are at least 250 (relative) for 2/3 the spectrum- much more consistent even output of the whole spectrum- and for Another they peak at 1000 (relative) way down around 440nm.

Sp what the hell does all this mean? It means (theorecticaly) that HPS is still way better for flowering simply because it pumps out so much orange light, but that if you get enough full-spectrum floros together you will outgrow any light at any stage of the plants life. Think of what that means though....a standard full-spec tube puts out about 2000 lumens of light that is actually better for growing than an HPS. BUT even a 400watt HPS puts out 50,000 lumens all on its own. So to equal the mid-high nm output of an HPS with full-spec floros you would need what...25 of them? At 40 watts a pop you are looking at 1000 watts......

However- you can't put an HPS very close to your plants AND lumenousity does decrease with distance AND you can put a floro right up against your plants...hmmmm, if lumens decrease with distance they must then also increase the closer the light source gets.....

""""A lumen is defined as the quantity of incident luminous flux (flow of light)which will, when distributed uniformly over a one square foot surface area, produce an illumination of one foot-candle on every point of the surface. One foot-candle is the equivalent of light output of one candle measured at a distance of one foot from the center of the flame."""""

So I guess the concept of "lumen" no longer applies when you are within 2 inches as opposed to one foot? Especially if you have a battery of lights and that one square foot is a space now occupied by one third the legnth of six floro tubes. One ft is 1/4 of a 4 foot tube, but with 4 tubes occupying that foot you actually have the energy output equivilent to 1.5 tubes covering each foot. 1.5 x 2000 'lumens' is 3000 'lumens', not even counting the energy multiplied by the close proximity of the tubes to the plant. If we are to use agent86's light-meter measurements of a floro 1' away as opposed to 1" away

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40 watt floro tube at 1' = 2,268
40 watt floro tube at 1" = 4,662
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Then we roughly double the lumens at that one inch point:

6000 lumens per square foot. Pretty close to ideal without using c02.

And I'm not even mentioning the possbilites inherint in compact full-spec floros: envirolites.

Bad ideas? Am I crazy? Tell me if you think this sounds like disaster waiting to happen because I am extremely tempted to go this route.

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late Bloomer

SkyHarvest
well put and well thought out. I wonder how I missed it the first time. I was looking in the space needed between plant and bulb and found this on a search. Good info! Would you, or any one, have some 'rules of thumb' for distance? I'll be doing the hand test, just looking for a ballpark number.

peace II

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"can you tell i'm a person who lives with lists? as a stoner, it's the only way i get things done." schreck
not me, but it is my life
I feel like I'm diagonally parked in a parallel universe

plainsman1963

SkyHarvest, by all means, post informational direct links. We just don't want commercial links "look at this company!" but for information or articles- link away!
For instance, this is a good link for artificial lighting.

Peace,
Plains

'eadStash

Help me, I'm broken......


Where'ju go??---

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plainsman1963

Well, at one time it was a good link...

Plains

Maninthebox

With that floro idea you get the hole spectrum, but intencity has a lot to do with it too. As I understand it, 400w will penatrate the canopy better. Try to think of it like heat. If you cook somtihng at 400 deg. for 2 hours to get it done, you can't just cook it at 200 deg for 4 hours and expect it to be done. You can't substitute intencity no matter how close you put the lights to the plant. I'm really interested in how that works out for ya cause I'm in the same boat as you. I've been though sevrail packs of smokes and at least an ounce of weed trying to figure the best way to light my next grow room. I did my first one with 8 4foot floro cool whites and swiced to full spectrums for flouring and it did ok, but its nothing like the pics in the mag. I'm really not sure how I'm gonna go, but I'm also lookin into the usefull ness of UV in the flowering stage..... It wouldn't be so bad if I had unlimited funds, I'd just get the best of everything out there and push the button. I think it all comes down to what you can do, and what your willing to do, but as a genaral rule, more light, better spectrum, any of that stuff helps, I just wanna know whats worth it for the $.