just learned somethin pretty cool.

So I bought a little 35$ light meter to fine tune my garden, I have 2 400w cmh coming in today and was taking some readings of my hps and mh before I switch them out. Each is puttin 7k footcandles at the tops of the canopy.

The packet that comes with the meter explains a bit about light and how to use the meter. It tells you how to read: LUMINANCE, ILLUMINANCE, TRANSMITANCE, REFLECTANCE.

And by taking an initial reading and subtracting Reflectance and Transmittance, you can get a good idea of light absorption, for photosynthesis.

Here's some interesting results.

Leaf #1
Light beside lush, green, nitrogen rich leaf: 6000k ftc

transmittance of same leaf : 3500 ftc (light that goes through the leaf)

Reflectance of same leaf: 1500 ftc (light bouncing off leaf

Leaf #2
Light beside lighter green, leaf 6250 ftc

Transmittance of same leaf: 4500ftc

Reflectance of same leaf: 2000ftc

Leaf # 3
Light beside yellow, nitrogen deficient flowering leaf 6250 ftc

Transmittance of same leaf: 5000 ftc

Reflectance: 2500 ftc

Now I'm not saying the remainder is what's absorbed but its a ratio of the reflectance or the transmittance to the illumination that is supposedly what's absorbed.

So afterall late in flowering your plants will be able to photosynthesize more efficiently with green, pr dark, chloro-filled (pun intended) leaves.

highly appreciated info, very interesting, it all seems pretty logical and I think obvious to experienced growers that healthy green plants have more energy. Not the best experiment for this but better than nothing Thanks for posting

Yeah I'm not sayin its the most brilliant thing ever but I def thought it was cool, proved a point and if nothing else showed a good use for a light meter that I didn't even know of till now.

Kinds of cool... You should do several experiements and see if you get some replicated patterns. Good info and I was always wondered how well light worked. What brand meter did you buy.