Ceramic Metal Halide (CMH)

[JohnnyToke]

lumens are useless to confront bulbs with different spectrums, but are quite useful with bulb of the same spectrum.


You can see this way (very simplified):

F(x) is a function, where x is the frequency of the light and F(x) is the output of the lamp at that frequence.

Then a lumen meter sample the light over 256 different frequencies, and mutilply the value of each frequencies for a different number T(i) and then divide for the sum of all the T(i) numbers.

By this way, some frequencies count more than others: the greater the associated T(i), the more important the frequence will be.

This is done because to the human sight some frequencies are brighter than others, therefore we can think as if it is introduced a correction vector T, i.e.:

Lumen=L(F, T)=<F(X.i), T(i)>/||T(i)||

l

where F is a function that represent the source of light that varies over the spectrum and efficiency of the lamp, L belong to the positive real, T the correction vector, and i the n-th sampled frequency.

But we are thinking lamp for plants, and and not for human sight. We know just the Lumen and not the function F, therefor T become an error vector and not a rescalation, making Lumen an useless factor when dealing with lamps with a different F, but it will be still useful when confronting lamps with the same F, since the error vectors will delete each other.


Conclusion: A CMH with 182 L/w and the same spectrum, is twice as better as a CMH with 90 L/w, since the efficiency is doubled.

very well written. It makes more sense now. Excellent post.

thanks

JT

 

[simba]

dito very well put..e definitely couldn't/didnt say it better myself

 

[SatoriSOG]

would a cmh bulb, or even an hps be effected if there was a speaker magnet near it?

 

[chicalyx]

Are the ballast kits on advancedlighting compatible with the CMHs? Ready to grab a 400 watt bulb and ballast kit and give the CMH a run.

 

[simba]

satori, hps doesnt care about oriantation.. so i would say no mag force wont affect HPS
MH, i doubt it..
Both within reason..

chica, yes as long as you grab the HPS 400 ballast not the MH-P ballasts (depending on bulb wattage)

 

[SatoriSOG]

alright, iwas just wondering since im gonna be runnin the cmh in a bass cab with large speaker magnets

thanks man

 

[simba]

that may pose an issue as subs are Stronger magnets then a standard woofer in a speaker (home speakers)

id say 12" away.. would be good.. (take one sub to a TV or something old and how far it is without interfering is the distance (each magnet is diff. .it could be close or far depending)

 

[SatoriSOG]

another thing im wondering, is what particular threat it might pose?possible fire hazard? bulbs burning out quicker? reduced power?

 

[gramsci.antonio]

heat dissipation and efficiency lost.

Go to your hardware store and buy some fine iron powder. Trow some where you suppose to place the lamp or the core. If the iron fall in a random way, it's okay. If it assumes the shape of the magnetic field, than it's too close.

 

[Hawk]

Back to lumens for a second....I get that lumens are useful for comparing lamps of the same spectrum and less useful for comparing lamps of different spectrums. That makes sense given lumens are weighted to a specific spectrum.

So what do we use to compare the intensity of lamps with different spectrums?

 

[gramsci.antonio]

Back to lumens for a second....I get that lumens are useful for comparing lamps of the same spectrum and less useful for comparing lamps of different spectrums. That makes sense given lumens are weighted to a specific spectrum.

So what do we use to compare the intensity of lamps with different spectrums?

up to today the only thing working i've seen is a system of Partial Differntial Equation. So i think that your best bet would be the direct experience.

 

[Hawk]

up to today the only thing working i've seen is a system of Partial Differntial Equation. So i think that your best bet would be the direct experience.

Thank you. I suspected there was no simple answer.

 

[BonsaiBud]

I'm sure it has been said before. The only true measure of a light bulb's output is an SPD. In long hand that is a spectrum power diagram. Combine this with the bulb's heat output relative to the task at hand. i.e. a lizard would appreciate all the infra-red coming from his incandescent heat lamp, although I have seen people breed Bearded Dragons in cages with 150 watt MH bulbs. But for plants, you need the SPD and the ratio of useful radiant energy to energy consumed.

Just in case anyone was wondering, light energy is measured in electron volts per photon. The the formula is energy/wavelength so hard UV (270nm) is super energetic compared to gentle HPS and incandescent.

I must also add that as the wavelength gets shorter, it takes more energy to produce each photon.

Perhaps we need to go back to the quartz prism and thermometer for want of a reference-grade SPD analyzer.

 

[knna]

I think i linked it before, but anyway ive released a new version of the Bulb Analyzer Tool. You need to enter the SPD to be analyzed (Phillips CMD is already digitalized, you can find it on the hand digitalizer sheet), and the power of the lamp and lm output to obtain the results.

Yelow cells are for introduce required info, while results are given in the blue cells. It calculate bulb (and system) energy efficiency, PAR watts micromols of photons delivered (PPF) aswell as many more parameters usefull to understand bulb's perfomance.

Enjoy it

 

[simba]

Knna, Thanks.. again for all the hard work ya do.. Great Technical skills.. and can communicate easily it to boot.

 

[romantiikka]

I have already four Philips cmh bulbs but when i search something else i found these:
http://www.drillspot.com/products/434467/General_Electric_CMH400_U_830_R_CMH_Lamps
Price for case of six:
GE #49910 CMH400/V/940PA/O $103.10 400w Clear High-Watt CMH SPXX ED37 Bulb EX39 Base 3600(k)
In here:
http://www.alldaylighting.com/HID_Lamp.html
Are these as good or something completely different kind of cmh bulbs?
Im going to wait generation 2 of Philips bulbs but these ones price would be nice before that.

 

[hoosierdaddy]

$103.10 each

 

[trichburner]

I have already four Philips cmh bulbs but when i search something else i found these:
http://www.drillspot.com/products/434467/General_Electric_CMH400_U_830_R_CMH_Lamps
Price for case of six:
GE #49910 CMH400/V/940PA/O $103.10 400w Clear High-Watt CMH SPXX ED37 Bulb EX39 Base 3600(k)
In here:
http://www.alldaylighting.com/HID_Lamp.html
Are these as good or something completely different kind of cmh bulbs?
Im going to wait generation 2 of Philips bulbs but these ones price would be nice before that.

difference in the color temp , CRI and the GE is listed for enclosed fixtures only . Philip's has a color temp rating of 4000k while GE is 3000k which I beleive is more to the red side of the spectrum . Not sure what CRI is , but Philip's is 85 and GE is 80 . Mean Lumens for Philip's is 29,600 and 31,300 for GE .

I'm sure Simba can explain those numbers better .
BTW - question for Simba on the spectragraphs . On the left side column labeled relative energy , what unit of measurement is being used ? microwatts/cm2 hopefully ?

 

[simba]

SPD output is Way different its 3k but they get 3k by bumping up yellow green..Short version..
ge's cmh are nice units (many bulb shapes avail in cmh version ie Mr16, but there spd for horti hasnt prooved worthy yet..
and we have and are testing ge cmhs. and sylvania cmhs;;as they both just came out with some cool stuff within the past year.. (prob more for commercial lighting not horti)
I WILL LET ALL KNOW IF WE START SUPPORTING ANOTHER CMH OVER PHILIPS BUT AS OF NOW ONLY PHILIPS 4K CMH ARE HORTICULTURE GRADE


CRI is not greatest for plants cri is how humen eye compares that light to full sunlight.. you can have same cri but way different color combo to make it up..
plant can notice that difference.. Again shortened version..

also ENCLOSED fixture ONLY>> NOT GOOD>> FOR US>>

that bulb has a max life of 20k hours if its in Vertical mode..

as far as the relative i have been asking for the exact rating since i started moving them.. and still only saying that it is Mw/cm2 (that is from the Lead Philips CMH Engineer) (that was said after we said we needed something or we cant go any further..)
so dont hold me to it but im holding them to it..
i did have a partner with an actual spectrograph thingy.. but wont hand over results unless we pay allot more.. Piss off. ill buy a unit for what he wants to test just the hps retro whites. i have many i want to test. accurately.... (note the unit will not measure total outputed rather the actuall radiation per nm range..

 

[trichburner]

SPD output is Way different its 3k but they get 3k by bumping up yellow green..Short version..
ge's cmh are nice units (many bulb shapes avail in cmh version ie Mr16, but there spd for horti hasnt prooved worthy yet..
and we have and are testing ge cmhs. and sylvania cmhs;;as they both just came out with some cool stuff within the past year.. (prob more for commercial lighting not horti)
I WILL LET ALL KNOW IF WE START SUPPORTING ANOTHER CMH OVER PHILIPS BUT AS OF NOW ONLY PHILIPS 4K CMH ARE HORTICULTURE GRADE


CRI is not greatest for plants cri is how humen eye compares that light to full sunlight.. you can have same cri but way different color combo to make it up..
plant can notice that difference.. Again shortened version..

Good enough

as far as the relative i have been asking for the exact rating since i started moving them.. and still only saying that it is Mw/cm2 (that is from the Lead Philips CMH Engineer) (that was said after we said we needed something or we cant go any further..)................
.....i have many i want to test. accurately.... (note the unit will not measure total outputed rather the actuall radiation per nm range..

Those are numbers a few of us would love to see , especially in the 300-400nm range . The graph on page one is OK , but it does give a rough idea of how the bulb compares to the sun . I would have liked to have seen the graph extended from 275 -300nm to about 750-780nm or so . Definately post up numbers if you get them .