Hello everyone!

As I felt I wanted try using another light source than my Osram 400 watt double ended HQI lamp, I spent my day try finding a better one. I knew Tian used LED's in his projector and was quite satisfied with the results, so I decided to make a comparison between different LED's and the legendary metal-halide lamp.

First, here's a table



I made it in Microsoft Excel and tried to upload it here but I'm not permitted to upload a file with that file extension (*.xls). If I had the possibility to upload that file, you could download it yourself and do like whatever you want with it.

I've probably made some miscalculations somewhere in the table and if you see any, feel free to inform me so I can correct it.

As you can see in the table I used a 8,4" display as a reference. To convert the LED's mcd and beam angle I used the "candela (millicandela) to lumen conversion wizard" at http://led.linear1.org/lumen.wiz. My conclusion is that LED's are way too expensive and too weak compared to the legendary metal-halide lamp. If the LED's gave more lumen/watt and were cheaper, they could be a challenger to the metal-halide lamp but at the moment, I think the metal-halide is the winner, in efficiency, price, lumen and color rendering index.

But in the feature, I wish the LED's will replace the metal-halide lamp since they are smaller (arc length) and sexier .


With best regards,
TJ

_________________________

* Edit 1: Changed the lumen/watt from 92,5 to 90,0 on the Osram lamp.

Wow... no reaction at all...

Nah, just no posted reactions.

I agree, not bright enough. Even on a 17 inch LCD.
I only looked closely at the narrow beam LEDs, I think ones with a wide beam aren't suitable.

I am agree LED are future not present. Too expensive and a very irregular colour render. That poor collour spectrum may be solved by discarting each white leds and replacing each one witha real RGB matrix composition to proyector. It create a very very rich colour spectrum, the best spectrum which we could dream.

--W---W---W--
RGB-RGB-RGB

So this increase a lot the construction and alignments. This form may let us increase or degrease R,G & B light independently.

Osram colour graph VS Led colour spectrum:

[font=Garamond][size=6]

In theory, the whole thing with LED's and replacing a theoretical 400W "MH" or "HPS" lamp is tuning the light output frequencies to match your desired application therefore achieving the same result with less luminosity. In the case of Plant life your goal would be to achieve a higher "PAR" or Photosynthetically Active Radiation ratio in your illumination source than the readily available, and inexpensive 40 some odd thousand lumen or better single lamp light sources. In my research several studies have been conducted you can probably find the information and many other useful sources of info on "PAR" and its associated wavelength's at www.actahort.org ... but they do want money for more than excerpts of articles and publications.
Acta Horticulturae®

Not sure if you're even using this for plants or aquatic plants but hope it may be of some assistance.

( Damn I wish they would put LED's on sale or something...)

The BUWC1363W10BA100 12 degree 10mm leds seem to be the best bet. They are the right angle and cheaper. No additional optics needed.

im sure this is the cheapest place to get the LED's they are $0.099 each so 500 would cost $50

http://www.hebeiltd.com.cn/?p=z.pricelist.led.diode

they do the 5mm and 10mm sizes, and the color temp is 7000k which isnt bad

the best one to get is the 3000mcd, 65 degree angle which gives out 2.9 lumens each

correct me if im wrong