{
moderator note: the following posts 1-8 were originally posted in the
SPD thread, but were split to this new thread thread in order to keep the data analysis separate from the data collection}
Hey!, very nice thread.
I want to contribute with a tool i developed to compare bulbs for growing.
It includes some spectrums.The way i digitalized spectrums is copying the spectrum to Paint(MS), zoom and put square mode (control+M), and use resize tool to adjust each square to 1, or 5, or 10nm. It would be a good idea if u do the same with the SPD of ur interest, and report it here.
Its an Excel table (i did it with Sun Open Office). U must introduce the output at each wavelenght (or 5 or 10nm band, depending of SPD resolution). Then, introduce the power of the bulb and the system (bulb+ballast) (if u dont know it, use the nominal watage), and the lm output (in Klm, u must divide lm by 1000).
The sheet provides info about bulbs photosyntetic action, but gives some valuable data about other concepts (red/blue ratio, total blue light emitted, near and far red output...).
Finally, the sheet report the bulbs efficiency, total micromols of photons emitted and their PUR (Photosyntetically Usable Radiation) value. Then, compute each PPF and PUR value per system watt (the most relevant data) and per Klm.
Obviously, the sheet refers to bulbs radiant power, and dont analize the way its emitted, but the PUR/Klm ratio permits to use lux data, about effective irradiation (ignoring the slight change in spectrum by the differential reflectance of reflectors and walls at each wavelenght, usually shifting to blue, as well by blues higher penetration power).
The main difficult issue when i was doing the sheet was what "photosyntesis action curve" use. Finally, i built one,
details in this thread. I choosed join a generic action spectrum with cannabis spectrum absorbance.
Of course, there is an error margin in the results, because SPD graphs arent a accurate font, and the quantum yield curve is an aproximation. And all depends of how much accurate is the lm rating. I trust mayor brands lm data, but take horticultural brands lm data with a grain of salt.
Enjoy it, introduce ur prefered bulbs spectrum and improve the whole sheet freely.