Someone school me on Lumens, candlepower, and so forth....

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[ARCHIVED THREAD] - Someone school me on Lumens, candlepower, and so forth....

Posted: 5/20/2005 11:33:08 AM EDT

Why do light makers not standardize on light ratings?

For instance, how many candlepower is in a lumen?

I recently bought one of those monster 15-million CP spotlights. It's bright. Easily illuminates stuff at 400 yards or more VERY brightly. But it's not noticeably brighter than a 5 million CP light...

How many lumens did a 4-d mag-lite make?

How is this output measured?

Posted: 5/20/2005 11:36:31 AM EDT

[#1]

They are different measure and cannot be converted one to the other. Lumen is a standardized measure, while candlepower is quite subjective.

Light measures

Posted: 5/20/2005 11:48:20 AM EDT

[#2]

I believe candle power is illumination in candelas in a single direction from the lamp (the place with the highest output).
It is more of a ratio of this highest point of intensity in the beam VS what equates to a 12.5lumen isotropic lamp. Isotropic means equal output in all directions.
The reflector comes into play with candlepower AND the method the manufactures take to get this number is often taken advantage of to look good.

Lumens is light output from the lamp, regardless of direction and reflector. Light output of the flashlight in lumens is the way to go as far as specifcation.

Posted: 5/20/2005 11:51:32 AM EDT

[#3]

tag

Posted: 5/20/2005 11:52:43 AM EDT

[#4]

www.candlepowerforums.com

Everyone's an f-ing critic!

Posted: 5/20/2005 11:53:30 AM EDT

[#5]

Quoted:
www.candlepowerforums.com

A mod who cannot use board code?

Let me warm up that link for Wave. www.candlepowerforums.com

Posted: 5/20/2005 11:59:22 AM EDT

[#6]

Quoted:

How many lumens did a 4-d mag-lite make?

*18 lumens for a 2D, 59 lumens for a 4D
*unconfirmed.

Posted: 5/20/2005 12:02:32 PM EDT

[#7]

Lumens, and Candlepower are both measures of how the human eye perceives light.

More scientific measurements would compare actual watts. Color temperatures also impacts the brightness. Lights that are high in output towards the middle of the spectrum tend to look brighter to the eye than equally powerful lights that favor higher or lower frequency light.

Reflectors also have a great impact on the brightness. A 10W bare bulb may not be as useful illumination as a 3W bulb with a decent reflector.

Lumens and Candlepower I believe simply measure light as it falls on a measured area. Better reflectors will boost this figure. Watts on the other hand will tell you how much light is being output.

Posted: 5/20/2005 12:03:25 PM EDT

[#8]

Quoted:
Quoted:

How many lumens did a 4-d mag-lite make?

*18 lumens for a 2D, 59 lumens for a 4D
*unconfirmed.

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

Posted: 5/20/2005 12:05:10 PM EDT

[#9]

Quoted:
Quoted:
Quoted:

How many lumens did a 4-d mag-lite make?

*18 lumens for a 2D, 59 lumens for a 4D
*unconfirmed.

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

This coincides with my own (unscientific) comparisons.

Posted: 5/20/2005 12:07:34 PM EDT

[#10]

Quoted:
Lumens, and Candlepower are both measures of how the human eye perceives light.

More scientific measurements would compare actual watts. Color temperatures also impacts the brightness. Lights that are high in output towards the middle of the spectrum tend to look brighter to the eye than equally powerful lights that favor higher or lower frequency light.

Reflectors also have a great impact on the brightness. A 10W bare bulb may not be as useful illumination as a 3W bulb with a decent reflector.

Lumens and Candlepower I believe simply measure light as it falls on a measured area. Better reflectors will boost this figure. Watts on the other hand will tell you how much light is being output.

Watts will tell you how much power is going in. If you know Watts and the lamp's spectral efficiency, then your getting somewhere. Allot of those watts are being coverted to heat.

With area, you are referring to foot-candles.

1)1 Lumen - the amount of visible light emitted by a standard candle through a solid angle of 1 steradian. Since a sphere has 4pi = 12.57 steradians, the standard candle emits a total of 12.57 lumens. (Of course, 1 Steradian is just that solid angle over which the subtended area is exactly equal to the radius of a sphere, so, 1 sq-ft of surface area on a 1 ft sphere covers exactly 1 steradian.) Foot candle = 1 lumen/sq-ft, which is the illumination from 1 standard candle at 1 foot range.

Thats where I got the 12.5Lumen reference.

Posted: 5/20/2005 12:07:56 PM EDT

[#11]

Quoted:
Quoted:
Quoted:

How many lumens did a 4-d mag-lite make?

*18 lumens for a 2D, 59 lumens for a 4D
*unconfirmed.

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

Much brighter - for sure. It's amazing. I own both.

Posted: 5/20/2005 12:08:26 PM EDT

[#12]

Quoted:
Quoted:
Quoted:
Quoted:

How many lumens did a 4-d mag-lite make?

*18 lumens for a 2D, 59 lumens for a 4D
*unconfirmed.

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

This coincides with my own (unscientific) comparisons.

Mine too.

I just wish ratings (both CP and lumens) were more available for more lights.

Posted: 5/20/2005 12:08:55 PM EDT

[#13]

Quoted:

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

Taking into account the superior reflector and light quality (white-ness)
Hell yea

Posted: 5/20/2005 12:10:07 PM EDT

[#14]

Quoted:
Quoted:

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

Taking into account the superior reflector and light quality (white-ness)
Hell yea

My mag-lite broke about the time I got my first 'modern' light, so while I thought that little booger was awfully bright, I didn't know exactly which one was brighter....

Posted: 5/20/2005 12:12:57 PM EDT

[#15]

Quoted:
Quoted:
Quoted:

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

Taking into account the superior reflector and light quality (white-ness)
Hell yea

My mag-lite broke about the time I got my first 'modern' light, so while I thought that little booger was awfully bright, I didn't know exactly which one was brighter....

My M2 (2-cell) has a 65lumen and 120lumen lamp.
So you can't simply go on a per cell basis.
Does the 120 look almost 2x as bright as the 65? Not to me.

edited for 65

Posted: 5/20/2005 12:14:06 PM EDT

[#16]

Just get a Surefire (or many)

Posted: 5/20/2005 12:17:46 PM EDT

[#17]

Quoted:
Does the 120 look almost 2x as bright as the 65? Not to me.

I have a 60, a 65, a 120 and a 200 lumen SFs and the brightness is about the same, what changes is the diameter of the iluminated spot at the same distance (the greater output, the bigger circle, of course)

They also reach more distance.

Posted: 5/20/2005 12:18:19 PM EDT

[#18]

Quoted:
Quoted:
Quoted:
Quoted:

How many lumens did a 4-d mag-lite make?

*18 lumens for a 2D, 59 lumens for a 4D
*unconfirmed.

so a 2-cell surefire is brighter than a 4-d maglight?

Cool.

Much brighter - for sure. It's amazing. I own both.

+1 Same here...my Surefire is WAY brighter than my Maglite...

Posted: 5/20/2005 12:26:54 PM EDT

[#19]

Quoted:
My M2 (2-cell) has a 65lumen and 120lumen lamp.
So you can't simply go on a per cell basis.
Does the 120 look almost 2x as bright as the 65? Not to me.

That's because our vision responds to light intensity in a logarithmic, not linear, scale.

Here's an example for you...go to www.fillfactory.com/htm/technology/htm/Logresfaq.htm and look at the second pair of pictures (the ones looking out a window).

The first picture was taken with a camera with logarithmic sensitivity, similar to the human eye. Note that you can see the trees outside quite clearly.

The second picture was taken with a camera with normal, linear response. Notice how the light from the window overwhelms the camera's dynamic range and renders the trees invisible...the window area is just a wash of light.

Hope this helps...

Posted: 5/20/2005 12:31:05 PM EDT

[#20]

Quoted:
Quoted:
Lumens, and Candlepower are both measures of how the human eye perceives light.

More scientific measurements would compare actual watts. Color temperatures also impacts the brightness. Lights that are high in output towards the middle of the spectrum tend to look brighter to the eye than equally powerful lights that favor higher or lower frequency light.

Reflectors also have a great impact on the brightness. A 10W bare bulb may not be as useful illumination as a 3W bulb with a decent reflector.

Lumens and Candlepower I believe simply measure light as it falls on a measured area. Better reflectors will boost this figure. Watts on the other hand will tell you how much light is being output.

Watts will tell you how much power is going in. If you know Watts and the lamp's spectral efficiency, then your getting somewhere. Allot of those watts are being coverted to heat.

I know that, heat is light, just invisible to the naked eye.

The highest efficiency bulbs put out as much light as possible in the visible spectrums.

That is why I think that lumens is sufficient to compare light outputs when visibility is the focus, but in a more scientific regard, Watts would be better.

Posted: 5/20/2005 12:33:02 PM EDT

[#21]

Quoted:
Quoted:
My M2 (2-cell) has a 65lumen and 120lumen lamp.
So you can't simply go on a per cell basis.
Does the 120 look almost 2x as bright as the 65? Not to me.

That's because our vision responds to light intensity in a logarithmic, not linear, scale.

Here's an example for you...go to www.fillfactory.com/htm/technology/htm/Logresfaq.htm and look at the second pair of pictures (the ones looking out a window).

This first picture was taken with a camera with logarithmic sensitivity, similar to the human eye. Note that you can see the trees outside quite clearly.

This second picture was taken with a camera with normal, linear response. Notice how the light from the window overwhelms the camera's dynamic range and renders the trees invisible...the window area is just a wash of light.

Hope this helps...

Thanks for the link w/ pictures.....because I'm way too slow to have understood that otherwise.

Posted: 5/20/2005 12:35:23 PM EDT

[#22]

Quoted:
Quoted:
Quoted:
My M2 (2-cell) has a 65lumen and 120lumen lamp.
So you can't simply go on a per cell basis.
Does the 120 look almost 2x as bright as the 65? Not to me.

That's because our vision responds to light intensity in a logarithmic, not linear, scale.

Here's an example for you...go to www.fillfactory.com/htm/technology/htm/Logresfaq.htm and look at the second pair of pictures (the ones looking out a window).

The first picture was taken with a camera with logarithmic sensitivity, similar to the human eye. Note that you can see the trees outside quite clearly.

The second picture was taken with a camera with normal, linear response. Notice how the light from the window overwhelms the camera's dynamic range and renders the trees invisible...the window area is just a wash of light.

Hope this helps...

Thanks for the link w/ pictures.....because I'm way too slow to have understood that otherwise.

No problem...I tried linking the pictures directly, but all I got was the dreaded red x, so I just put the link to the page...

Posted: 5/20/2005 12:37:34 PM EDT

[#23]

Quoted:

That's because our vision responds to light intensity in a logarithmic, not linear, scale.

Good point, as does our hearing.

Posted: 5/20/2005 12:37:39 PM EDT

[#24]

Do NOT leave your surefire on and then put it in your pocket.

You WILL burn yourself.

Sgat1r5

Posted: 5/20/2005 12:39:50 PM EDT

[#25]

You want BRIGHT??? Try a 1000 watt metal halide lamp...they run around 110,000 lumens of brilliant white light...

Posted: 5/20/2005 12:39:51 PM EDT

[#26]

Quoted:
Do NOT leave your surefire on and then put it in your pocket.

You WILL burn yourself.

Sgat1r5

My surefire is on the forend of my 870. It will NOT fit in my pocket.

(my other light is a streamlight - I won it at gunstock, and it works great.

)

Posted: 5/20/2005 12:41:33 PM EDT

[#27]

Quoted:
Do NOT leave your surefire on and then put it in your pocket.

You WILL burn yourself.

Sgat1r5

Yeah, those fuckers throw a shitload of heat, don't they???

Posted: 5/20/2005 12:43:20 PM EDT

[#28]

I think many of you will enjoy this website

Flashlightreviews.com

they have most of the common lights all different bulb styles so you can see the actual numbers for incadescends, LEDs, Luxan led's etc

[ARCHIVED THREAD] - Someone school me on Lumens, candlepower, and so forth....

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