# 1,000,000 candlepower lumens?



## Genxsis

I know this may be open to speculation, but would anyone happen to know about how many lumens a 1,000,000 candlepower spotlight typically puts out?


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## Illum

Um...your mixing two different units here

Candlepower is the measurement of light intensity, Lumens is a measurement of total light output, or illuminance, and equals to [lux] / [meter squared]

Of course, that doesnt mean the question has no answer

[font=Arial, Helvetica, sans-serif] Lumens are a metric equivalent to foot-candles in that they are measured at an object you want to illuminate.
Divide the number of lumens you have produced, or are capable of producing, by 12.57 and you get the candlepower equivalent of that light source. [/font]One candlepower equivalent equals 12.57 lumens.
[font=Arial, Helvetica, sans-serif]
so Lumen rating should roughly equal as follows:

"Capable Lumen" = "candlepower" x 12.57
SOME ONE PLZ CORRECT ME IF IM WRONG

something didnt sound right.... heres my source, maybe its my interpretation
http://www.theledlight.com/lumens.html
[/font]


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## Solomon MK2

That definately doesn't sound right!  



> "Capable Lumen" = "candlepower" x 12.57
> SOME ONE PLZ CORRECT ME IF IM WRONG


 
So you would need 12.75 million lumens to = 1 million candlepower! :laughing:

I can tell you right now, that is just plain wrong!


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## winny

Illum_the_nation,

I don't mean to be rude or offend you, but just about everything except for your first line is wrong. Just a little friendly notice as yor said you wanted to be corrected...


Genxsis,

I would expect those "1 MCd" spotlights to use slightly underdriven (due to crappy joints and circuit breakers) 100 W halogen bulbs with crappy reflectors so my guess would be about 1000-1500 lumen here. If you really measure the light intensity from one of those, like once Spacemarine did, you get about 50-100 kCd, depending on model and rate of change IIRC.


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## AlexGT

An eyeball measure would be about 1200 to 1500 lumens

AlexGT


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## Illum

winny said:


> Illum_the_nation,
> 
> I don't mean to be rude, but just about everything except for your first line is wrong.
> 
> 
> Genxsis,
> 
> I would expect those "1 MCd" spotlights to use slightly underdriven (due to crappy joints and circuit breakers) 100 W halogen bulbs with crappy reflectors so my guess would be about 1000-1500 lumen here. If you really measure the light intensity from one of those, like once Spacemarine did, you get about 50-100 kCd, depending on model and rate of change IIRC.




Thats why I wanted a correction...What I read from LEdlight doesnt make sense to me one bit....

I researched on this once, but I sorta gave up on it...




AlexGT said:


> An eyeball measure would be about 1200 to 1500 lumens
> 
> AlexGT



How do you eyeball things like this...a neighbors 500,000 candle power spot light left after-images for hours....I think that was after I got glasses, oh well, PS: My eyesight got worse...to the point where I can't see the knob in my shower with or without squinting...so, yes I wear my glasses in the shower....rust resistant coating...isn't


_So um...guys, Can someone plz tell how to convert cp to Lumens accurately rather than just eyeballing the whole matter?_


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## winny

Illum_the_nation,

I got you, but I should have written that along with friendly somewhere too. I'll edit it.
My guess what AlexGT meant by eyeball measure is compared to a known output from another lamp (with similar output), he would estimate the output to 1200-1500 lumen.
The "afterburner" effect has probably not very much to do with you wearing glasses or not. There are big individual differences and it comes with age as well.

To convert from light intensity, measured in candela (same as candlepower but defined by Système International d"unités) to luminous flux, measured in lumen, you need to know the beam profile if your spotlight/flashlight. The beam profile tell you how much light it outputs in each direction. From there, you can integrate how much total luminous flux you have. The far easier version when it comes to spotlights with somewhat asymmetrical beam profiles is to use an integrating sphere or a shoe-box painted white instead and a light meter. That way the integration is done for you so it's only the easy part left.
Bottom line, without knowing the beam profile (or beam spread if it's symmetrical and even) YOU CAN'T CONVERT LIGHT INTENSITY [CANDELA] INTO TOTOAL LUMINOUS FLUX [LUMEN].


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## jeffroalpha700

Actually, there is no way to convert lumens to candlepower. You are talking about two very different measures, illuminance vs. luminance (apples vs. oranges).

Lumen - energy of 1/683 joules per second, measured at a wavelength of 555 nanometers.

Candela (candlepower) - lumens per steradian. (A steradian is a solid angle subtending an area of R squared at distance R from the apex.)

Simplified, a lumen is the measure of the total light output of the light source (this is the luminance (radiance) of the light source.)

Candlepower is measuring the brightest spot of a beam and is reflector dependant. If you take a Mag flashlight, just by focusing the width of the beam, you can adjust the "candlepower." The luminous intensity stays the same.

For those physicists out there that are going to correct me on the convertible relationship, I know. I understand the inverse-square law, etc., but that doesn't apply for all practical purposes to this discussion.


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## jeffroalpha700

Winny,

It looks like your post went through while I was typing. You opened up a can of worms I was trying to avoid concerning the beam profile!


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## Genxsis

Thank you for the replies! I was just wondering about how many lumens that would be since everything on the forum is measured that way, I was just wondering how something like one of those spotlights would compare to a standard handheld if someone just wanted to go for sheer brightness regardless of portablility.


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## Illum

Thanks for the reply...I know of this Luminous flux business, learned in Physics...short two years ago...


this "lumens per steradian." ...
I guess I fell asleep during this lecture...





Boundless Enthusiasm for lights...

edit: boundless enthusiasm for _the exterior design of_ lights...


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## Dustin Liu

Illum_the_nation,

:huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2:


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## winny

jeffroalpha700,

I'm sorry but my explanations are always like that. When I try to make them easier to understand by using analogies, they are always bizarre and involves food according my friends. When I tried to explain how a gear box was a form of impedance matching for a girl in class, it involved frying hot dogs so you can say I lost her respect for my explanation there and she laughed like crazy...
Anyhow, your explanation looks alright but keep in mind that candela is the base unit for light and you derive lumen from there, not the other way around.


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## hector

Lumens, as said before are total light output. CP, basically, is intensity at one spot. CP is a function of focus, lumens measure how much light is coming off the bulb BEFORE getting focused, generally they are not convertable. So, you can have a maxabeam with 1,000,000 CP be overall less bright than a 500 watt halogen. But which one would you rather have?


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## Illum

Dustin Liu said:


> Illum_the_nation,
> 
> :huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2::huh2:




nvm...I was thinking out loud


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