Repost. Need help with information war.

I have some friends and such that do not understand candlepower and candela.

Perhaps I don't fully get it either. To me, candlepower is the same measurement of intensity as candela, accept, that most companies somehow advertise numbers much higher than they really are.
A person has even said so much as a halogen light they had was 15 million candela. I dont believe any incandescent or halogen light achieved that much brightness.

Does anyone know if halogen lights ever achieved more than 2 million candela or so? I've personally purchased a light that said had 2 million candlepower but somehow was out-thrown by my fatmax light.

Let me know what you think.

Here's a lighthouse that previously used a 1kW tungsten-halogen incandescent to produce 900kcd.

https://lighthouses.org.au/vic/gabo-island-lighthouse/

OP, I cannot understand how your title applies to your topic posted here.

I think you will get more and better help if you Edit it to give a better sense of your specific question.

Bazar said:

I have some friends and such that do not understand candlepower and candela.

Perhaps I don't fully get it either. To me, candlepower is the same measurement of intensity as candela, accept, that most companies somehow advertise numbers much higher than they really are.
A person has even said so much as a halogen light they had was 15 million candela. I dont believe any incandescent or halogen light achieved that much brightness.

Does anyone know if halogen lights ever achieved more than 2 million candela or so? I've personally purchased a light that said had 2 million candlepower but somehow was out-thrown by my fatmax light.

Let me know what you think.

Click to expand...

Pretty much any product coming out of Asia (mostly China) the numbers are inflated by at least 10X and likely even 20X. There is no integrity from these companies !
Can you sue them for false advertising ? No you can't, this gives them no legal reason not to lie.

Agree 100% with XeRay. Let's see if we can explain a little better.

Lights emit photons. A photon has 2 important properties for our purposes: its direction and its frequency (or color or wavelength). All light sources will emit a range of frequencies. The range can be enormous in the case of the sun (from gamma rays to IR) or rather narrow in LED for example.

The human eye cannot see all the frequencies. The ones detected by eyeballs are called visible light. We are most sensitive to green.

A given light source will emit light in all directions (spherical emitter like the sun) or in some directions only (LED for example).

When I compare 2 light sources, i need to consider direction and frequency (or wavelength). Key point: the human eye does not respond equally to all wavelength AND it more or less works on a log scale. You need a 10X increase in light hitting your eyes for your brain to think that the brightness increased by 2X.

Now to your question:

A candela is a measure of light intensity (# of photons), CORRECTED for the sensitivity of the human eye (green counts more than IR or UV...) per solid angle (think of a cone in a certain direction).

Lumen represents the total intensity of the light. When I use optics to focus the beam in a certain direction, I can increase the # of candela in that direction (and only in that direction).

Bottom line: think about advertised candela as a measure of visible light at a specific angle. A very lower power source that was focused along a very narrow beam would have very high candela ratings but would not be useful as a flashlight.

All of that said, advertised # are meaningless and grossly inflated, especially from overseas manufacturers.