knna

I want to explain the difference between both concepts.

Radiance data relates to the light emission point (bulb or better, the whole fixture). The sheet analyces this. It measures absolute units: total lm emited (or uE, or light watts).

We usually just has the radiance data. How many lm we have installed. And we know the space it lights. Suppose you has 55000 lm in 0,7m2 (7,8 sq ft). You can refer it in absolute average terms: 55000lm/0,7m2=78571 lm/m2 (or 55000/7,8=7051 lm/sq ft). Although expressed in lm/m2, or lm/sq ft, still is an absolute data, wich gives a reference of the light used in any space.

Irradiance data relates to the surface receiving the light. Its very relative, because although it relates directly to radiance, depends fully of the point its measured: varies a lot with distance (square law refers to irradiance, not to radiance, wich is absolute), but too with type of reflector, walls reflectance, etc. The only way to measure it accurately is with a luxometer.

The sheet compute the PPF/Klm and PUR/Klm to obtain this data from lux measurements. This is the data growers might be more interested.

Another concept is the difference between photometric measurements/units (lumen, cd), human related, and radiometric measurements/units (watts, uE) wich are objetive and not human perception weighted. There is a direct conversion between, so when i explained the radiance/irradiance concept, you can change lm by uE perfectly. I prefered to explain it with photometric units due to people used to them.

Hope this explanation helps people to understand better the thread.

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Bulb Analyzer Tool

Quantrill

phillips ceramic metal halide 400 watt

Attached Thumbnails

 

Attached Images

 

Attached Files

Phillips ceramic metal halide.zip (17.6 KB, 51 views)

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Each man must for himself alone decide what is right and what is wrong, which course is patriotic and which isn't.

~Mark Twain

knna

Thanks, Quantrill. hope the guys debating about this bulb appreciate your effort, too

An explanation of results:

-Low capacity of induce photosynthesis: just 0,76pur/w, 30% less than a typical 400w HPS bulb (Phillips SONT plus).

-Spectrum itself very blue, thus the low relation PPF/PUR:65%, while HPS are between 69 and 75%. This parameter shows how is the spectrum for using the photons emited into photosynthesis. R/B ratio is 4, very adecuate for vegging.

-But the difference in spectrum against HPS is little (10%), while the main difference is in the bulb efficiency: just 26%, while the SONT have 33,6%, wich is near 30% more light emited per watt consumed.

So potential yield using this bulb is about 30% less than flowering with a HPS. Of course, there is qualitative advantages not shown, wich can compensate partially: more compact plants (better light usage, less light losses), healthier grow, better CO2 absortion. But its very difficult this compensate for 30% less photons avalaible, wich is very much.

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Bulb Analyzer Tool

Quantrill

redid it with 5 nm increments




some one may want to check it for accuracy

I think bluebloodletter has some questions for you knna, over in AB's cheap bulb thread.

Attached Thumbnails

 

Attached Files

phillips CMH with 5 nm increments 2.zip (19.6 KB, 23 views)

__________________
Each man must for himself alone decide what is right and what is wrong, which course is patriotic and which isn't.

~Mark Twain

Profound

pardon me....(BUMP)

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knna

I upload a newer version of the sheet, just minor modifications to make its results coherent with avalaible data (now it just compute uE in PAR, without taking into account far red in the final results)

Attached Files

BulbsComparision_v2.zip (103.8 KB, 62 views)

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Bulb Analyzer Tool

Quantrill

ummm...

so it uses 300-700 nm?

and far red is what nm?

__________________
Each man must for himself alone decide what is right and what is wrong, which course is patriotic and which isn't.

~Mark Twain

knna

The sheets now calcalates the same, from 380 to 770nm. This is the visible range of humans, although human's eye sensibility is very low below 420nm and over 700nm.

In fact, you can find many info saying UV starts at 410nm and below and infrared starting at 700nm. But i use the CIE parameters, and the photopic curve, wich shows eye's sensibility from 380-780nm. So tecnically, near IR starts at 780nm.

The 380-400nm range is often included both in the UV and the visible range.

The far red range goes from 700nm to 780nm.

But definition of PAR (photosynthetically Active Radiation) is defined mainly between 400-700nm, so i choosed to make the sheet compatible with this definition. The only difference is i included the 380-400nm, because this range has still photosyntetic capacity, although its low, but enough to be considered. As photons in this range carry very high energy, including it varies very little results agains pure accepted PAR range (400-700nm), i decided to include it.

Unfortunatelly, many SPD graphs only shows the 400-700nm range, so results are incomplete. But it not affects in a noticiable way the accuracy of the sheets on the data showed, because photometric effect of other visible wl (380-400nm and 700-780nm) are very, very little.

What i changed is including the far red (700-780nm) in the final results, although the raw data is still avalaible in the sheet, in order to make possible calculate R/FR ratios. But like the info provided for manufacturers are PPF between 400-700nm, i choosed to eliminate far red in the resume.

It make sense in the mean that wl over 700nm has very little photosynthesis capacity itself, although its proved that the 700-720nm still has some noticiable effect, but mainly due to Emerson's effect, wich shows that 700nm light can enhance photosyntesis of red light. But this effect is dependent of the light density, because its caused by a best sincronization between PSI and PSII, so its not a easily computable effect. I didnt included any sinergy effect like this in the sheet, and choosed to make it coherent with most botanist data and way of presenting results.

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Bulb Analyzer Tool

amine

SPD of Aquarium Metal Halide Bulbs:
(these are originally from Advanced Aquarist's Online Magazine - Advanced Aquarist's Online Magazine and has been taken without their permission).
Original SPD's. (They're higher resolution).
Advanced Aquarist's Online Magazine - Product Review: Spectral Analysis of 400W Metal Halide Lamps: Giesemann, Krystal Star, South Pacific Sunlight, BLV, Catalina

Quantrill

We have tryed to keep the collection of SPD's in a seperate thread that was started a couple years back. http://www.gardenscure.com/420/light...ous-bulbs.html

Some of the ones you posted may already be archieved there.



Please do input the data for the lamps that you are interested in into the bulb comparison tool spreadsheet, and post the results for discussion here.

If you need help with the data entry please ask, and I or certainly knna will gladly help as best we can.

__________________
Each man must for himself alone decide what is right and what is wrong, which course is patriotic and which isn't.

~Mark Twain