regularguy

OK all
Ive got a job and stuff so i had to drop out of the thread for a bit as my real life called. Using the proper equation

I=L/A

with
I Illuminance
L lumens
A area of sphere = 4pi(d^2)

the actual lumens put out at the following foot candle readings varied. It shouldnt and i will give my reasons and presumptions later.

One EVL
inches foot candles Lumens of bulb
12---------300------------------3770
10---------700------------------6100
8----------900------------------5025
6 ---------1200------------------3770
4 ---------1800------------------2515
2--------- 3000------------------1050
1--------- 4500------------------3925

2 EVL lights
inches foot candles Lumens of bulb
12 ---------- 875------------------10995
10 ---------- 1250------------------10900
8 ---------- 1500------------------ 8375
6 ---------- 1800------------------ 5655
4 ---------- 2500------------------ 3500
2 ---------- 3000------------------ 1050
1 ---------- 3300 ------------------ 2880

Now, none of the calculated lumens come out to equal the advertised lumen reading. I would guess that if you take the average and disregard the readings 4 inches and closer,see reason 2a, you get an average lumens of 4500. And for 2 bulbs, 9000.


OK the lumens for the bulb should have all equaled the same number but they don’t for various reasons.
1.human error in measurement
2.hot spots from the reflector
3.too close to the reflector and it is not a sphere you are measuring anymore
4.The bulbs measured were old
5.The output of these lights is not in the green spectrum so the light meter doesn’t measure it "correctly". I am doubting this one because either mist or agent said that the EVL appeared so much brighter than a MH lamp. The brightness would indicate more output in the green than the MH lamp.


Reasons that the readings were either too low or too high.
1a.The reflector makes it only part of a sphere. This would make the measurements given the highest possible because you are intensifying the light where you are measuring and then saying that it is that intense over a sphere which it is not.
2a.They would be wrong altogether at the close distances to the light because you cant make a sphere around a point source if the point source is bigger than the sphere you are making.

HPS readings
feet foot candles lumens
1 ----- 2250----- 28200----- 400hps
2----- 5000----- 252200----- 600hps
2----- 5200----- 261250----- 1000hps
1----- 180----- 2260----- 40w flouro
.0833--3700----- 3872----- 40w flouro

Same notes about the readings appy to these also.

Comments?
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