Luminus SFT40 LED - Beam Shots (Convoy M21c; unofficial)

[ArtieT59]

@Tom E

He's explaining the reason why I was using 5 x 5, which is 5 squared. If you measure at 1 meter, the lux reading is equal to the candela. But if you measure at 5 meters, you have to multiple the lux reading by 25 (5 * 5), or if you measure at 12 meters, you have to multiple the lux reading by 144 (12 x 12). So you can measure it at any distance, just square the distance, in meters of course. So the lux reduces dramatically as you move the light source further away from the meter.

I use 5 meters - it's easy for me indoors, and it's the distance others use as well. Some lights might have a well formed hot spot at 5 meters though, but it's worked well for me. It's probably better to be 10 meters or little better. If you are much further away than 10 meters outdoors, then atmospheric conditions can reduce the reading.

At shorter distances, you have to be more accurate. 2 inches at 5 meters is more critical then 2 inches at 10 meters.

great explanation, thank you. Yea I'm not the brightest.. so .. Jaredm's comment went right over my head lol. Thank you both though. Abd Tom your explanation marks perfect sense. It seems to me that by doing that it ensures that no matter the distance the readings are comparative. And it also allows you to find the bear distance for any particular light's reflector, because I've read maybe lights with significantly more throw measure better or are more concentrated at further distances like 10meters, like say maybe the k75 or something. I don't know, I'll try a couple others for the hell of it.

[Bardo219]

Those outdoor beam shots has made this very tempting for me! I might have to pull the trigger on the wurkkos fc12.

[johnhanks]

One sample is that this new brand Cyansky, their K3 flashlight adopts the sft-40 LED since it is published. https://cyanskystore.com/products/k3-long-range-tactical-flashlight. Beam 1600 lumens and 600 meters maximum.