[Need help] SWM V20C 1m lux value wanted

jh333233

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I want to know how bright my V20C is as i expected a XML to be a thrower even with a medium hotspot
But even my "E2e-sized" 18650 XR-E blows v20c away
Many flash light reviewers have a luxmeter and some of them own V20C too, may i request a little favor for a 1m lux reading of V20C?
Cuz ive searched with the keywords [V20C, lux] and resulted in no wanted results
Thanks
 

xul

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At 438 lumens = 438/4Pi = 35 cp. so at 1 meter from a bare bulb you'll get 35 lux. I think you need to know the beam/field angle. A 300 meter range (means 1 lux at this range, the 'moonlight standard') implies a narrow beam so you'll get many times this value at one meter.
 
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phantom23

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Lux has nothing to do with lumens. V20C has about 6000 lux/1m. It's not much but big emitter (XM-L) and small reflector = floody beam.
 

jorn

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The xm-l will always be blown away compared with a similar sized light with a xr-e (throw wise). The xm-l is a huge led and it needs a huge reflector, and lots of amps to throw. The xr-e is many times smaller, so it don't need a huge reflector to throw. The surface brightness of the xr-e is brighter than a xm-l (surface brightness + size of the reflector is what makes a light throw). The xm-l is "brighter" (more lumens) only because its bigger than the xr-e, but it's "glow" is dimmer so it will throw less. The old xr-e is still one of the best leds if you want throw. All the newer led's gets bigger and bigger with lesssurface brightness and ofcource more lumens. But bigger and less intense leds is bad if you want something throwy.
 

xul

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Lux has nothing to do with lumens.
V20C has about 6000 lux/1m. It's not much but big emitter (XM-L) and small reflector = floody beam.

In the world of sales and marketing, you're right. Numbers and formulas that can be independently verified are about as welcome as the Plague.

4Pi lumens = 1 cp. A 12.57 lumen point source of luminous flux at 1 meter gives you 1 lux of illumination. Unless my ancient physics book is wrong.

6000 lux @ 1 meter gives you 1 lux at 77 meters. This a little short of 300 meters. Sumpin's wrong somewheres.
 
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jorn

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Your old book is prob not wrong. But it dont take relector/led size into the math.
You cant matematicly make lumens into lux as long as there is variables surch as led size/intensity, and with reflectors involved. A laserpointer has way less lumens and way more throw than a xxxx lumen household bulb.
 
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