MDOCOD,
Multiply by ten ???? Make that 40 !!!
The Thors I got my hands on all had reflectors with large imperfections in the shape, but those imperfections were not big enough to pull down the theoretical cp-performance. However you are absolutely right about the importance of the lamp-position, I should have mentioned that I checked the reflector-performance AFTER repostioning the lamp..
Ofcource if I would use a lamp with a much smaller filament or arc, the imperfections will become a problem !!
ThatGuy: You are right on the spot !!
And Mac:
At some distance from a torch the entire reflector should be lit by the light-source (filament or arc). From that point the light follows the inverse square law: So if you incease the distance 2-fold you should measure 1/4 the lux-output. So if you go from 1 meter to two you divide by four, not 3..And from one to 3 meter indeed you divide by 9.
The reason: If the reflector is fully lit, the amount of lux an object receives is determined by the apparent dimensions of the source, the surface brightness does not change! When you increase the distance from 1 to 2 meter, the apparent diameter of the reflector will be divided by 2. And when the diameter is divided by 2, the surface is divided by 4 !! So the object "sees" a surface 4 times smaller at 2 m than it does at 1m. So the lux readout at 2m will be 1/4 th of the lux readout at 1m!
.. But the numbers I posted are exactly folowing that inverse square law! So are not linear !
1,500lux at 100m equals 100x100x1,500 so 15,000,000 lux at one meter...
And 150,000 lux at 10m = 10x10x150,000= 15,000,000 at 1 meter
If your torches do not follow the inverse square law, then you are probably measuring the lux-output too close to the torch. (reflector not yet fully lit by the source..)
Ofcource actual measurements will be influenced (?) by the absorbtion in the atmosphere and the tolerance-differences in acurracy of the various ranges of your lux-meter.
Regards,
Ra.