Is my math correct?

LED Flashlights – General Info
1

Hi:
I notice that the Acebeam k75 has an output of 6,300 lumens on Turbo and a candlepower of 1,562,500.
If my math is correct(maybe not?!) one candlepower equal 12.57 lumens…so 6,300 divided by 12.57= 501.193…big difference between 1,562,500 and 501.193, no?Thanks,HB

2

That only works when the light is uniformly distributed in three dimensions, like form a lightbulb.
That equation does not hold when you have a reflector or other optic directing some of the light in a particular direction, because then you redirect most of the lumens in the forward direction, which increases the candlepower without changing the lumens.

3

Thanks! HB

4

:+1: np

5

no relation between lumen and CP, CP is about directionality and concentration, lumens is about total light .

6

CP or candela is a measurement of lumens per area, so yes they are very related.

OP’s question is about the parent equation 1cd * 4pi steradians = 12.56lm

What he didn’t know is that this is just for a uniformly lit sphere, which has an area of 4 pi steradians.
If the area is less (like a flashlight that only emits light forward), the lumens per candela are less, aka more candela per lumen.

7

My comment may not be valuable to experienced members, but for me as a beginner:

This concise article on the personal website of forum member "dave1010" about "Converting Candela to Throw" helped me understand the difference between lumens, lux, and candela. I especially enjoyed the explanation for the ANSI measurement of throw and how this relates to moonlight and practical expectations.

8

Thanks for posting that article…I ‘think’ I understand it somewhat.HB

9

Please note that 6300 Lm is manufacturer rating, it will probably don’t achieve that and will max out at 4500-5000 Lm or so