More on this point. If you take a look at the par tests from Growershouse's blog almost every single LED fixture (cob or otherwise) suffers from covering a 2 x 2 far too well (the PPFD readings often go beyond what plants will even use) and then it falls off a cliff for the other 12 square feet outside of the center. I think this is probably why initially people complained so much about LEDs. HPS in a proper reflector did a better job in distributing the light out over a grid. The "reflectors" that attach to the cob, as well as the lenses, seem to focus light again to a smaller region than what the cob itself naturally emanates (eg, 90 degree reflectors whereas the cob itself has a 115 degree distribution pattern). How do you know the reflector isn't just causing the footprint problems that LEDs commonly suffer from in the first place? Any insight you may provide is appreciated.
I just stumbled upon this, those lights are AWESOME. Would be perfect to expand my already existing bar with 4xCXB3590.
I have lenses on them, so you are correct talking about "problems" with spread. I have an 120x60cm area and due to how the lights "combine", the outer sides/edges of my growing area are getting significantly less light, this is easily to test even by a simple "hand under lights" test.
ON THE OTHER HAND, I don't really see this as a problem. Arrangement and type of your fixture/COB is everything here! This is why I am now also saying that individual lights (that you can move) might be better than a fixed bar with 4 lights, like I have.
BUT...knowing that the outer, say, 15cm of my growing area are getting less light is less a problem in actual practice. In reality I always have some plants like seedlings or vegging plants, I simply put them on the outer range of my growing area. I don't see this light distribution "problem" as such a "problem" at all. In fact, it's actually good that I have a safe space for seedlings
As for PPFD, you're correct as well. I am actually *using* 1.15x0.57 from my area which is 0.65sqm and I have 4x CXB3590 with a 1750mA driver.
Fully turned up I get close to 900 PPFD. Good. But when I am vegging and don't have anything in flower, I can "only" dim down to 550 something PPFD, the lowest setting with the internal dimmer, 875mA (Which is still a lot for vegging, 250-300 PPFD would be sufficient). I just realized *recently* that I have way, way too much light when I veg only and run the lights fully turned up, at least according to theory...