Ok.
I recently got a cheap lux meter (hyelec MS6612)
Trying to get my head around measuring lux (never done before)
I built an L2 with LD2 (6A) driver and dedomed XML2
I got out the tape measure and measured out 2M
-At 2M the lux meter measured 48,700 lux
So 48700 x 2²= 195Kcd?
-At 3M the lux meter measured 24,800 lux
So 24800 x 3² = 223Kcd?
I also tried a foursevens X10 with 3A driver and XPL HI
At 2M I measured 1310 lux
So 13100 x 2² = 52Kcd?
Someone help me figure this out!
It takes some distance for the beam to fully form. Measure at 10m for more accurate numbers.
The most I have in my living room is 7 meters, so that is my distance to measure throw, not ideal but pretty ok. So the throw is lux times 49.
With cheap luxmeters beware of very cool tints, in all cheap luxmeters (and even in a $200+ Extech meter, I noticed recently) the blue peak in the led spectrum is over-measured, and can lead to lux/throw numbers that are several percents or even 10 percent too high, even if the meter is correctly calibrated (they do that with a 2700K light source).
In general the more throw a light has, the father away it takes to get an accurate reading. I always used 4 meters. On the upside if you measure too close your measurements can’t be high so you won’t get inflated numbers.
Yeah I understand with throwers it’s better to be far away, but finding the room is an issue!
I’ll try an stretch it to 4/5 meters, see what I come out with