Lumens vs Candlepower
I have a two part question, I am going to buy a "combat light" to use with my Sig. Not mounted to it, just a flashlight. Are there any others that compare to Surefire?? Also how do you compare power, when one is rated in candlepower and one is rated in lumens?? I can't find a good definition of either.
Thanks, Kc
Thanks, Kc
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Lumens is a measure of light flow equal to one international candle which is the illuminating power of one standard candle. Which is really deep if you what an explaination. Look in your encyclopedia under candella also. Basically a lumen and candle power is roughly the same. As to lights I and brands I would get one that I like and am comfortable with that can take some abuse. 0 -
Thanks for the reply. I have read several definitions that basically say candella = lumen, If this is true, Then the advertising statements I was using for comparison are off by a few thousand ? I guess until I learn for sure, I'll just have to look directly into each light, then count the seconds till the spots go away.The longer it takes, the higher the Lumella's. suuuueeeeeee!
Kc0 -
From what I understand they are both totally different measurement systems. Its been a while since I was told so forgive me if I'm mistaken, but I believe one is a measure of volume of light while the other is a measure of brightness.
If this helps any I can say from experience that a 65lumen surefire 6p flashlight is brighter than a 3 cell mag-light.
If I'm wrong please correct me, I won't be offended.
The sound of a 12 gauge pump clears a house fatser than Rosie O eats a Big Mac !0 -
Hey Kc, look at it this way. Candlepower is the unit used to measure the intensity of a light source. The lumen is a measurement of the light flux emitted by a source of light. Accordingly, a 60 watt lamp puts out about 870 lumens, whereas a 100 watt lamp puts out about 1710 lumens. We all know that a 100 watt light bulb is brighter than a 60 watter, right?
There are two ways to look at candlepower of a point source; one is "mean horizontal candlepower" which considers only that light from the source in a horizontal plane. The other is "mean spherical candlepower" which includes all of the light emitted in all directions from the source.
The formula for the latter is, I=Fs/4Pi.
So, if you've got a light rated in total lumens from the lamp, then its candlepower is equal to that number divided by (4 x 3.1416).
Don't damage your eyes by looking at too many bright lights!
OleDuk0 -
Wow, thanks for that post, I've gotta print that out.
If I'm wrong please correct me, I won't be offended.
The sound of a 12 gauge pump clears a house fatser than Rosie O eats a Big Mac !0 -
Now that sounds like the definitive explanation. As far as what is comparable, check out the little Streamlight Scorpion. I use the Surefire but bought my youngest son a Streamlight. Never a problem with either, they seem equally bright and the Scorpion is cheaper. try this link for specs http://ss02.lynk-systems.com/southernpoliceequip/html/spotlights.html
AN ARMED SOCIETY IS A POLITE SOCIETY0 -
Thanks for the replies. OleDuk, Since you're the winner in the " I'm in the dark, about light, contest, I have another question for ya. I've already decided on my flashlights. Surefire C-2 at home with the Sig, and a large Streamlight rechargable in the truck. At the risk of looking like a total idiot- I'm still not clear on the intensity formula
I= Intensity ?
Fs= Flux sphere?
4x3.1416=12.566 I=Fs/4Pi
so if i've got 65 lumens
Candlepower = 65/12.56
Candlepower = 5.17
Perhaps I have looked at too many lights, but I dont think I'm doin it right Thanks Kc0 -
Naw, Ksubc, you've got it right.
I= intensity (candlepower)
Fs=mean spherical light flux from the source
4Pi=12.566
And your example is correct.0 -
Whats the expression, --Beating a dead horse--
Surefire C-2 = 65 Lumens = 5.17 Candlepower, yet appeared to be be as bright or brighter than the stinger I was comparing it to, which is supposed to be rated at 15,000 Candlepower.
I think I'll do my own "consumer report" comparison testing, and rate them all using- Seconds Till The Spots Go Away- I better save the Q-beams till last. Thanks, Kc
Great board yall got here.0 -
Hi again, Kc. Sure doesn't seem to add up does it? I believe that
I'd think that we're dealing with another type of measurement here called "mean zonal candlepower" which is used when all of the light from a lamp is concentrated in a small angle by reflectors and lenses as is done with searchlights and spotlights. My old text book "Light,Photometry, and Illumination Engineering" Third Edition doesn't give much detail on this and as a matter of fact refers the reader to the Illumination Engineering Society Handbook for more details on this topic.
I think a good way to compare two spotlights with similar lenses and reflectors would be to get the wattage rating for each light and pick the one with the highest rating which would give you the brightest light. It would save wear and tear on your eyes,too!!!0 -
Wish I knew how to edit my previous post! Really though--I think that the manufacturer could give you those ratings. The more watts, the brighter and better. This might just be the cleanest way to make the comparison as long as the spotlights themselves are configured similarly.
Wish I could be more helpful!
OleDuk0
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