GG707, you know I am a huge admirer of your grows, BUT, without being brand specific, I do not see where a centralized concentrated light can compare to one that spreads its' spectrums EQUALLY over a 3 x 3 area
How can a small footprint light compare umoles at the perimeter?
Tell me where I'm wrong
Here is my take in it and this might be a little squirrelly...
Your statement/question has some inferred conditions/opinions...
#1...you said concentrated...as if TOO concentrated. Or that it is a bad thing agaist what the plant wants...
And #2...that spreading it makes it better suited for the plants and canopy.
You have assumptions in your mind and are keeping you from looking at what matters...WHAT DO THE PLANTS WANT!!! and what is getting that.
Then #3... since you are asking me specifically right after an apache recommendation and BML reference...it seems that you are saying/thinking the AT600 is the concentrated and the bml is the spread light
Prioity #1- Meet the plants requirements...700-1200µmols peak and 300µmols outer edges.
Priority #2- To spread that light as much as possible with out over doing it and dropping under the threshold of great growth.
Priority #3- To get that light to meet the requirements from as far away from the plants as possible...this translates to penetration.
I would rather hit 1000µmols and have smaller coverage than try to spread it and have it fall to 500-600µmols. The results under the properly lighted area should surpass the half ass lighted canopy.
I would also rather have a panel hitting 1000µmols peak and 300µmols edge from 24" than a light hitting 700µmols for most of the canopy form 12".
Blending is important and more distance from canopy to lamp allows for the best light interaction IMO. As well as increasing penetration power of the light assuming it keeps the same intensity, but from higher up.
This can also all be looked at from the true PPF(total possible output) numbers of each lamp...good luck finding/getting them though. But if available would show to a degree the capability of the lamp.
With theses 3 covered the light should not be too concentrated or too spread. Anything other than doing that is compromising to a degree somewhere.
And now to take this to a brand specific example because that is where it needs to go...
BML vs Apache.
BML is 36"x36"...
Apache is 32x30 roughly...
Now which one are you saying is spreading the light and which is concentraded...?
As much as an AT seems concentrated...it's fucking big in physical size and is "spreading" the light better than you think...while also being untouched in intensity and penetration.
Unless you have a specific light vs light your would like to ask about...your question isn't really going to get a direct answer since the concepts of being "too" anything is subjective unless you look at what/how it is meeting the plants requirement.
And also you can take as many readings all over the canopy...add them up...and get an idea of which canopy/situation is receiving more photons on the canopy...even if not perfectly even.