Is it just me or we seem to have the same discussion every six months and nothing changes
I see,
lumens could be significant or not, it depend on what kind of light you compare
sometimes you don't know if your HPS draw more lumens than others because its radiometric efficiency is higher or if its spectrum is more green ( as instance)
lm/sq ft could be used only with HID I think, it's a bad means to measure but whitout radiometric efficiency, people couldn't use anything else
HPS do a great job, I agree . (I prefer CMH, the spectrum is pretty )
But it's not caused by lumens, If you have said to me, HPS draw 40% (35% maybe?) that's why it works fine OK but not lumens.
Or explain me in what the 200lm/w is important
When I said colour ratio is more important than absorption, The two are linked ( sometimes I think ) so it's not really true
And if you want to make a panel 200lm/w with high peak at 660nm, you've got two solution
-an excellent radiometric output 60%?
-a high peak at 550nm or near to
Funny thing is that many CMH growers have reverted back to running HPS bulbs in the last weeks of flower to improve yields.... same strains and everything hmmmmmmm
terrible CRI and terrible spectral output
way better CRI and way better spectral output BUT yields less........why?? product quality is better though, I've seen it myself that yields decrease compared to HPS.
CMH bulbs (100-105lm per watt) vs HPS bulb (135-145lm per watt) Is the ONLY advantage for the HPS.......HAS been driving me crazy for some time now, Science says otherwise but it's performance doesn't lie. We all know that Plants will adapt to MOST light sources soooooo== Extra energy/photons "thrown" onto the canopy DO matter even if NOT optimal.
As for the LEDs I want in my panel......well were NOT there yet tech wise but I foresee something like this in the future
http://www.cree.com/led-components-and-modules/products/xlamp/arrays-directional/xlamp-xml-color 3 emitters being 200lm perwatt WW and one emitter high lm/per watt 660nm(if cree ever makes one
)all under one glass/pmma capsule. Perfect blending!!!
BTW anyone see this
http://www.cree.com/lighting/products/outdoor/streetlights/xsp-series-streetlight $99 for a CREE streetlight, hmmm should do well.........come on homedepot, jump on this........so we can see what Captain can do with it!
http://www.heliospectra.com/sites/www.heliospectra.com/files/field_page_attachments/what_light_do_plants_need_2012-10-05.pdf
I am still a "all about par" guy, cause the par is the amount of energy in the light. A study like that shows that the whole spectrum is still very well used...even if not exactly in the peak zones.
Exactly................500-600nm are important!!............as much as 450 & 630/660nm??? IDK
but doesnt that like say green only makes sense when u made sure red and blue is like fully covered, as long as thats not completly true any "full spectrum/white/green" is a waste (except peaks of those in r/b) because r b is used more efficient? How to tell when that point is reached, when its rather better to implement more white or green in a fixture then more r and b?
R/B/DR are considered the most "efficient" blend........BUT even Hans put two white leds to "balance" out his panel, Always told me he would never add white emitters due to their inefficiency........so what gives? ? Personally I think ALL plants will do great under full spec white, It's time for simplicity and having a comfortable work environment. I can't take the pink/purple hue anymore! really!.........gives me fucking headaches and I can't see shit. If I was running a large OP, their is no way I would deal with that crap even if I lose efficiency.
I don't buy into the whole 'lm per watt' stuff. That is a great way to measure efficiency for general household lighting, but doesn't work for spectrum specific lighting. Blue light has a very low lm per watt ratio, but extremely high in energy output, called HEV light.
http://en.wikipedia.org/wiki/High-energy_visible_light What that means is even though it is very poor in lumens and lighting up a room, it actually provides more energy for photosynthesis than a 130lm per watt white LED in some applications.
To really use PAR or lumen per watt to make comparisons, they need to be the same type of light output (ie. MH, T5HO, and CFL should only be compared to white LEDs, once you try and compare them to colored LEDs everything falls apart)
Yes, IMO it is very easy to build a 300w LED light that is capable of producing the same output for growing things as 1200w of HID. My 140w LED light on my aquarium puts out more light than 1200w of HID. I actually believe the light I made now, that uses 215w, will be comparable in 'plant' output to 1800w of HID once I swap a few LEDs out and finally put the optics on the LEDs. The lenses were back ordered when I made the light and came a month into the grow so we decided to wait until the second grow to take down the light to add all the lenses. We have had a few other issues to learn about and resolve that were more important for our first grow (ventilation, nutrients, fighting PM).
Yes we all know about the blue leds and their ability to push photons
..........Oh and their is NO fucking way a 215w led panel will be comparable to 1800w of hid with todays tech. MOST skilled/dialed in HID growers running 2 600w hps will yield above 1200g DRY, you realize that right?? your 140w panel producing the same would be around 8.5g/per watt!!! Come on now........were stoners, but not stupid.
I might not have explained myself properly. What I meant was that lumen is only a useful measure of light if you want to know how bright it seems to you.
If lumen is all you want, then go for a ton of 555 nm LEDs - at this wavelenght the sensitivity of the human eye is at its peak, and you will get most lumen.
Lumen has no relation to how well it works for a plant. For plants can 1000 lumen beat 2000 lumen, if the spectrum is right.
That's why lumen is useless - which was my point
Hope it makes sense now.
Bet you MJ would grow and flower under a 555nm panel......maybe
................check above^^^post about a better(less lumen) spectral output in fact getting beaten(yield) by a crappier (higher lumen) spectral output bulb. YES their are exceptions to everything, I just don't understand how at this point(2013) we are not out-yielding old HID tech with all these fancy new PAR/PUR tailored led specs and panels??? That's why I'm suggesting to copy HID.....
Sky read this paper and you'll get a better understanding in why lumens/watt, uMole, kelvin, lux, footcandle is so unimportant in relationship to how way plants absorb light.
http://www.inda-gro.com/pdf/MeasuringPlantLight.pdf
The other major issue facing mfg's is the lack of an industry standard for a plant sensitivity curve that mfg's can design lamps to meet the absorbance regions of a specific plant. Earlier I referenced a German standard DIN 5031-10. While that is often pointed to as the reference in a specific lamps spectral radiometric output calibration. Even this DIN standard has not been widely accepted as a broad enough to satisfy a generalized sensitivity curve for a majority of terrestrial plant species. That being said the standard may ultimately end up being issued broken down into species types or even perhaps at a minimum of vegetative or flowering plants to be of real use to the gardener having to select the best lamp for their application.
While spectral distribution graphs are a nice graphic depiction of the lamps output the Y axis is typically shown as a unit of relevant intensity value and not an actual power produced by the lamp that fall within that region. I like the ability to see the actual PAR watts/region (this could also be listed as a PPF uMole/Region value) which shows how much usable power can be found in these regions. I think most mfg's will adopt this 3 part strategy unless that is they don't produce balanced radiant power within these regions which would make them less willing to show their lamps output in that format.
View attachment 2796343
View attachment 2796344
View attachment 2796345
Great points...............but it still doesn't explain why HPS still out-yields everything
I understand the skepticism. If I didn't know what I do about light/photosynthesis, I would be in the skeptic camp as well reading my statement.
I admit, this is completely unscientific as we don't know the exact numbers for the plant we are growing, so I am using the standard absorption graphs. I do have a PAR meter and both a 'poor mans' Spectrometer and lab grade spectrometer (at work) to break down light into spectrum/intensity in a crude manner. What I mean when I say a 215w LED matching the output of 1800w of HID comes down to PUR, not PAR. My 215w with optics should put out as much PUR as 1800w. Without optics it already beats 800w of HID in PUR output. PUR = Photosynthetic USABLE Radiation while PAR is Photosynthetic Active Radiation.
Anyone interested in making their own spectrometer cheaply, here is a link. I have the 'VHS box' type at home and it does work well for the cost.
http://publiclab.org/wiki/video-spectrometer-construction
Their was this movement up until last year in the T5 camp about using PAR/PUR specs with fancy aquariums bulbs, was started by professor
https://www.rollitup.org/indoor-growing/358190-led-without-leds-my-first.html was exciting and everyone jumped on it.........In the end what did the skilled growers stick with? back to their trusty outdated/generic 2700k & 6500k bulbs and getting better yields with it too. hmmmmmm that yellow/green spike was in fact useful or was it the 20-25% lumen increase by going back to white????????????
Always a fun and educational talk when you come around chaz. And maybe in my life(I am younger than most, but have been growing for longer than most) but I will have boughten/used many many lights by then unfortunately.
My point is they all have their place but we as buyers also need to know things too.
I just always come back to seeing it the same...If it has a good spectrum, how much power(par) is there? And if it has really high par...first how much/well is that par dispersed over the grow area?....then what's spectrum? and watts used to do it all?
Skyled...I fell ya. I could tell you know what your talking about, just checking. I can't really speak any other language, let alone have an intelligent internet conversation with some foreign(to you) speaking stoners.
Great posts TAGS!!!!, and Chaz is no dummy when it comes to indoor lighting...........but he will disagree with everything I just posted
.........if you get over even 500g dry with 215w led I'll bite off my own pinky!I think your underestimating the light requirements for cannabis indoors. Spread out your leds too far for better coverage and your light intensity drops significantly.cluster them all together and add optics your coverage drops significantly.......see a pattern? Got to up the wattage per square foot for any decent yield, even with led.
That is how much faith I have in myself being able to build a great LED light. Right now I am pretty clueless about nutrients in DWC, so unless someone has a 'perfect recipe' to follow, that is the one area I need to do the most learning in in order to get my yields increased, but believe me, I am searching, reading, and experimenting now with nutrients so I can figure out that part of the puzzle. 
