gcbryan
Flashlight Enthusiast
There have been other threads regarding light meter measurements including one that was 600 or so posts long! Those generally relate to how to tell if one individual's light meter is giving similar reading to those taken by another individual.
My question however has more to do with the methodology of taking lux readings at more than 1 meter especially for "throwers" to allow the beam to fully "mature" and then converting the number back to 1 meter.
What generally happens is that the converted numbers end up being much higher than the actual 1 meter numbers.
However, at some point the numbers should be close to the same. Measuring at 3 meters and then at 5 meters and converting them both back to 1 meter.
In addition to testing aspheric lights which fit the pattern above I tried testing a light that was diffused. In this case the 1 meter reading was higher than the 3 meter reading converted back to 1 meter (the opposite of the aspheric case).
I'm not doubting the inverse squared light law but at some point the beam should be stable and the numbers should be more or less the same.
Has anyone ever taken two readings (at any two different distances) and had the numbers be close to the same? If not why not?
My question however has more to do with the methodology of taking lux readings at more than 1 meter especially for "throwers" to allow the beam to fully "mature" and then converting the number back to 1 meter.
What generally happens is that the converted numbers end up being much higher than the actual 1 meter numbers.
However, at some point the numbers should be close to the same. Measuring at 3 meters and then at 5 meters and converting them both back to 1 meter.
In addition to testing aspheric lights which fit the pattern above I tried testing a light that was diffused. In this case the 1 meter reading was higher than the 3 meter reading converted back to 1 meter (the opposite of the aspheric case).
I'm not doubting the inverse squared light law but at some point the beam should be stable and the numbers should be more or less the same.
Has anyone ever taken two readings (at any two different distances) and had the numbers be close to the same? If not why not?
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