Hi Grow Bros:
Well I went ahead & bought a light meter. It gives readings in foot candles not lumens so I did the conversion to lumens for the figures below. 1 foot candle = 12.6 lumen.
Here we go, I did measurements with1 light on & then both lights on & here are the results.
All measurements were taken below the center of the bulb.
I guess I screwed the conversion up so I came back & edited it.
Thanks to Powercow9 These #s are now correct.
1' = 3,780 lumen
10" = 8,820
8" =11,340
6" = 15,120
4" = 22,680
2" = 37,800
1" = 56,700
at the bulb off the scale.
With 2 lights on.
These measurements were taken directly between the bulbs. I'm sure the reason the lumens start going down in comparison to 1 bulb is that the closer I got the lights were to the side of the meter & the meter was pointing at the center of the reflector not one of the bulbs.
Here are the results.
1' = 11,025 lumens
10" = 15,750
8" = 18,900
6" = 22,680
4" = 31,500
2" = 37,080
1" = 41,580
Here are some measurments I took at the lighting store of some other lights for comparison.
These probably are not very accurate as there were other lights on in the store. Nothing real close but I'm sure anough to skew the readings slightly.
400 watt HPS at 1' = 28,350
600 watt at 2' = 63,000 anything closer than 2' caused the needle to go off the scale.
1000 watt at 2' = 65,520 not much more than a 600 watt.
40 watt floro tube at 1' = 2,268
40 watt floro tube at 1" = 4,662
Hope this helps to figure things out.
I'll be watching to see what you brainiacs come up with.
BTW, Here is a pic of the light meter I used. It has a photovoltaic cell that reads the light intensity.
Later Grow Bros.
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