Greg and i were having a conversation on illumination. candle power is more over rated than lumens. if you want to find out true light output, lumens is an actual measurement found by shining the lamp into a light meter. some lamps dont throw out what they say in candle power but some throw out more. like the thor lamps, some say the are not 10 mil candle power. so, is there any relation between candle power and lumens? i found this....... Lumens = Candle power x 12.566, so back to the question..... is there a relation of candle power to lumens?

I found this in a coal mining handbook i have from 1939:

The common unit of light intessity measure in this country is the standard candle which is that light given off by a candle made of spermacetti ( the brittle, fatty substance obained from the heads of sperm whales). six candles to weigh exactly one pound, when the candle burns at the rate of 120 grains ,approx 1/4 ounce, per hour.

The Candlepower of a light source is the number of times it is stronger of more intense than the standard candle. a ten candlepower light source is just ten times as strong as a one candlepower light source.

Illumination is the state or condition of being illuminated or lighted. the intensity of illumintaion is measured by a unit called the foot candle.

the illumination of a surface is determined by the foot candles of light falling on that surface, and not by the candlepowerof the light source. The intensity of illumination varies inversly as the square of the distance from the light source. Doubling this distance reduces the illumination intensity to one fourth its previous value. at three times the original distance the intensity of illumination becomes one ninth as great (why flashes dont work good for distance in mines).

Candle power and foot candles are measures of intensity and do not indicate the volume of light given out by a a light source. the unit of light volume or quanity is called a lumen. if a surface with an area of one square foot is illuminated uniformly with an intensity of one foot candle, the total volume of light recieved by the surface is one lumen.


so there you have it!


chris

_________________
Come over to the Dark Side....... We have Cookies!

sweet.

_________________
This ain't longwall... this is long hole!

I thought illumination was a state of mine, err mind.. Like when one becomes enlightened.. Whats this stuff about candles and lumens?

_________________
www.abandonedmines.net

Surprising, some of the Carbide Lamps put out some pretty good light and are much older than your $2 flashlight. Put a big reflector on the Carbide lamp and that thing is pretty bright.

Miner Greg