aeiou
Active Member
so what you are telling me is that light intensity is dependent on surface area? because if thats what youre saying then you are crazy.
Compound Lighting?
- Thread starter BSIv2.0
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herballuvmonkey
Well-Known Member
now wait a minute because while i do agree with closet in some aspects there is also another part to this. while 2 400 watters would be equal to 100k lumens (each being 50k lmns) where the light overlaps you would most likely be getting higher lumen output on that particular part of the garden, i would assume 1.5 (so 75k lmns). i would say ur best bet would be to make the most efficient use of having 2 400 watters. i.e. one 800 might be more in lumens (110K lmns) so ur losing 10k lumens by splitting it into 2 400s but by positioning them in a way to get the best coverage u probably will do better (i.e. yield wise) at the end
herballuvmonkey
Well-Known Member
wait let me correct myself. assuming its hps putting out 110 lmn/watt then an 800 would put out 88k lumens whereas 2 400s would put out min. 100k lmns so u really wouldnt be losing any output while increasing coverage. hhmmmmmmmm very interesting i think maybe ill try that on my next room design. thanx dude
nongreenthumb
Well-Known Member
400w puts out 50,000 600w puts out 95,000, the 600w bulb is the most efficient watt for lumens.
nongreenthumb
Well-Known Member
Light appearance is dependant on surface area, of course it is if you don't understand that then you are crazy.
aeiou
Active Member
no i dont understand that at all and i have a ******... hmmm. i guess i must be crazy. light appearance? im talking about intensity. every different surface material will reflect light in a different way but that has nothing to do with the actual output of the light itself. why would surface area matter? a light will put out the same amount of light with or without a surface to reflect on. surface area comes into play when we are talking about light coverage on a particular area and we would then be talking about irradiance. now with a reflector or mylar a light will "appear" brighter. this is because the light is being reflected and therefore less light is lost to a different direction or absorption. in this case our eyes see more of that light so the light looks brighter. here again the output of the light has not changed and again surface area doesnt really matter. the light appears brighter because the overall system has been made more efficient.
nongreenthumb
Well-Known Member
You may well increase the amount of photons that actually hit the plant because using two light sources as opposed to one fixed light surface will let those photons hit the plant from different angles which is why you will get an improved yield but hitting precisely the same spot with two light sources of equal outpet will not increase intensity on that particular spot. So surface area IS what matters because your allowing x amount of lumens to hit the plant from more areas allowing the plant to produce more chlorophyll and in turn more sugars which will improved the yield.
To use 2 x 600w on the same plants to cover two light sources to improve yield is a waste unless space is limited you would be far better served to just use them on different plants.
aeiou
Active Member
and here again your talking about coverage therefore yes surface area does matter. however, none of that has anything to do with light output and intensity. i agree with you that surface area and light coverage are both huge factors when attempting to increase yield, but the fact of the matter is surface area has no effect whatsoever on the output of a light. like i said before, dont confuse intensity for irradiance.
aeiou
Active Member
agreed... now lets stop arguing and start tokin'Seems to me if you are asking will i get a better result if i put 2 400 watt fixtures above my plants.
Answer is yes.
No you will not get anywhere near the equivalent output of an 800 watt bulb but you will see an increased yield
One thing that nobody has mentioned is the "Inverse Square Law", that's the main reason that I try to keep my grow areas square - as opposed to elongated. Roughly stated, the Inverse Square Law is: "As the distance the light travels is doubled; the intensity of the light is deminished to one quarter".
Given the 9'x2' grow area; that means that for a single, centrally located, light the photons would have to travel 4 1/2' to illuminate the end of the grow (would anybody choose to keep thier light 4 1/2' above thier plant?). With two light sources, spaced as I suggested earlier, the farthest that photons would have to travel would be 27" (as opposed to 54"), half the distance - therefore four times the intensity!!! So, yes, I still say two small lights are better than one big one, if they are spaced properly. The reason "everybody" doesn't do it is economical - they're just to cheap to spring for two lights.
The advantage of multiple light sources isn't so much about minor differances in total luminosity as it is about keeping the "plant to light distance" down to a minimum. Remember, half the distance means four times the intensity.
Given the 9'x2' grow area; that means that for a single, centrally located, light the photons would have to travel 4 1/2' to illuminate the end of the grow (would anybody choose to keep thier light 4 1/2' above thier plant?). With two light sources, spaced as I suggested earlier, the farthest that photons would have to travel would be 27" (as opposed to 54"), half the distance - therefore four times the intensity!!! So, yes, I still say two small lights are better than one big one, if they are spaced properly. The reason "everybody" doesn't do it is economical - they're just to cheap to spring for two lights.
The advantage of multiple light sources isn't so much about minor differances in total luminosity as it is about keeping the "plant to light distance" down to a minimum. Remember, half the distance means four times the intensity.