Sure can, but is it specified then that infrared (heat) and (possibly) UV
radiation is included or excluded in those watts? Also, I believe that
those light outputs in watts are even less in consideration of the
subjective "feel" of the light.
Lasers tend to be rated in watts of output.
This has only very rough correlation with lumens of output.
Output watts or milliwatts are "radiometric", meaning power, or energy
per unit time.
Lumens are "photometric", which takes into consideration a "standard
human eyeball"'s "photopic" spectral response.
One watt of 555 nm yellowish green light is 683 lumens. But, one watt
of 632.8 nm red is about 163 lumens, and 1 watt of 650 nm red is 73 lumens.
1 watt of 685 nm (a longer deep red wavelength of some early visible laser
diodes) is a mere 8 lumens. 1 watt of 405 nm violet is a little over 3
lumens, but looks brighter than that to "night vision" (favoring shorter
visible wavelengths) and causes many fluorescent objects to fluoresce with
as much as 100's of lumens (theoretical limit of 500).
One watt of 532 nm, a common more-luminous green laser wavelength, is
604 lumens. Get a 532 nm laser pointer when you need the most brightness
from the 4.9999 milliwatt limit of Class IIIa - at that wavelength, 4.99
milliwatts is 3 lumens.
One watt of invisible infrared or invisible ultraviolet has zero lumens.
Watt or milliwatt figures for laser output have fairly good correlation
with ability to cause burns, including to irreplaceable photosensors in
the eyes. Lumens has less correlation, since different wavelengths have
greatly different lumens for same watts or milliwatts.
Output of lasers is usually rated in *radiometric* units, as in watts or
milliwatts. Output of lightbulbs is usually rated in *photometric* units,
as in lumens.
- Don Klipstein ( email@example.com)
I look at the lumens.
As a result, I know that most dollar store 100W incandescents produce
about the same amount of light as 75W "standard" incandescents. And that
dollar store 75W incandescents tend to not outshine 60-watters worth
And, that superlonglife vibration-resistant 3500 or 5,000 hour rated 75
or 100W incandescents hardly outshine "one wattage lower" of "standard"
incandescents. (That is 60 or 75 watts respectively.) Decreasing
electricity consumption by 15-25 watts often easily pays for cost of
buying more lightbulbs, when one has a need for incandescents.
Stock up on shorter-life higher-efficiency versions of incandescents
*with good lumen figures* while you can, if you have a need for
Exempted from the upcoming USA ban are less-efficient
shock/vibration-resistant and "traffic signal" versions, along with many
others such as most under 25 or over 150 watts, all having "design voltage"
outside the 110-130 volt range, all having a base other than
right-hand-screw of E26/E27 size, and a few others exempted on basis of
shape, size or color of the bulb.
There are minimum lumen standards for Energy Star rated non-incandescent
40W equivalent - at least 400 lumens
60W equivalent - at least 800 lumens
75W equivalent - at least 1100 lumens
100W equivalent - at least 1600 lumens
150W equivalent - at least 2600 lumens (IIRC)
"Better" 120V incandescents have lumens in these ranges, & these lumens/watt:
15W - 108 to 126 lumens (life expectancy 2500 hours) 7.2-8.4
25W - 180 to 210 lumens (life expectancy 1000 or 1500 hours) 7.2-8.4
40W - 440 to 505 lumens (life expectancy 1000 or 1500 hours) 11 - 12.6
60W - 840 to 890 lumens (life expectancy 1000 hours) 12 - 14.8
75W - 1150 to 1210 lumens (life expectancy 750 hours) 15.3- 16.1
100W - 1670 to 1750 lumens (life expectancy 750 hours) 16.7- 17.5
150W - 2800 to ~2920 lumens (life expectancy 750 hours) 18.7-19.5
200W - 3800 to ~3980 lumens (life expectancy 750 hours) 19.0-19.9
300W - 6100 to 6300 lumens (life expectancy 750 hours) 20.3 - 21
- Don Klipstein ( firstname.lastname@example.org)
Radiance is the correct term for total light output. Lumens is an
amount hitting a surface at a particular point. Add a lens and the
Lumens will increase at some point. add a reflector and Lumens
increase at some point. A flashlight hAs high lumens in a spot. When I
start reading about candlepower, I start to get a headache.
There must be some kind od standard rating Lumens, because it's all
about distance, like 100lumens at one meter or foot. The farther away
the light, the lumens goes down since lumens is the amount falling on
a surface from a light. Candle power is light output looking at the
source of the light.
No, "luminance" is the correct term for (visible) light output.
No, a lumen is the visible light output of a one candela isotropic source, per
steradian (4pi steradians per circle so the entire output of the 1 candela
source is 4pi lumens). Distance is not a factor since the energy is measured
over a solid angle.
Cannot tell you what the brightness numbers are per foot. What is
your application. We have used short runs pretty effectively in some
museum display cases where we wanted indirect lights. It is best to
keep them out of sight with simple baffles.
When I visited a museum in Shanghai China some of artifacts display case
had auto dimming light. When there is no one near the case the light
dimmed very low, when some one approaches it goes back to normal
brightness to save energy as well as cause minimal harmful effects on
the item which is VERY old.
Depends on brand and color and how many LEDs per foot. I've seen dim
ones that looked like theater/airplane escape lighting, and ones bright
enough to put over crown molding high on the wall, and use for indirect
room lighting. They're pretty cheap- buy a string and play with it.
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