My head hurts.
Mist
Your post made me laugh in a good way.
frshnugz
Variables are just letters. Call them what you want.
There are so many different ways to measure light and most seem to suck. I think it is because they use the old english system for lumens and then some people switched it to metric and whatnot. Whenever i was in school, ive taken physics 1 through 4, we NEVER even used a lumen. I mean they arent even in my books. The accurate way to measure photon energy, including visable light, is Joules per second. Rarely do even the light manufacturers use this because most people are to stupid to understand it so myths and gereralizations about lights start spreading.
If the light manufacturers rated lights in J/s they would have to break it down for every wavelength and it would be very helpful. You would be able to look at a graph an say "wow look at all this energy this light puts out at 450nm. That would be perfect for my grow." Most of society doesnt even grasp the fact that lights are just photon emmiters and all the designers are doing is using different phosphors to get the bulb to emmit different wavelengths of photon energy. If we could get this information all the sucky lights would sit on the shelves while our plants grow major buds.
Horticulture is the only profession that cares about these things and we dont buy enough lights. When the average person goes to a store to buy a house light you care about the color temp(what the light emmision looks like) which IMO is useless because it says what the light appears to look like to your eye NOT what the actual emmisions spectra is.
LOOK AT THIS TO SEE WHY COLOR TEMPERTURE DOESNT MATTER THAT MUCH COMPARED TO THE SPECTRUM
Look at how many lights your city buys and compare them to indoor planters of all kinds. It is not even close. It seems philips outside of N America is making some good lights as well as other companies like Sylvania Orsam. At least as far as MH/HPS is concerned. So I think we have to wait until NIST makes a standard that everyone in the US follows or just buy the bulbs that were designed for growing that they dont distribute in the US in order to get a good grow light.