ryan constantine wrote:
>
> do these take into account brightness intensities or just colors?
Well, I haven't dig up most of the intensity data but here's an example:
One standard candle: 13 lumens
60 watt incandescent lamp: 1 000 lumens
1500 watt incandescent lamp: 34 000 lumens
So a 60w light is 80 times brighter than one candle.
Light `flow' from a lamp is measured in lumens. A uniform point source
of one candela (luminous intensity in any direction [defined for 555 nm
radiant intensity of 1/683 watt per steradian] ~ one dinner candle) at the
center of sphere of 1 foot radius gives 1 lumen per square foot. This is
also one lumen per steradian. Area of the one foot sphere is 12.57 sq. ft.
so the 1 cd. source produces 12.57 lumens.
______________________________________________________________________
Kari Kivisalo http://www.kivisalo.net
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