Lumens vs. watts
- Thread starter Randy Wel
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JohnnyBravo
Enlightened
Re: Lumens vrs watts
There is no direct proportion/formula. The newer standard appears to be lumens. Used to be candlepower years ago. Since the power management/efficiencies of different lights, bulbs, LED emitters, etc vary so much, watts can't always be considered a reliable barometer. One light may advertise 5 watts! While a different light may only use 2-3 watts, but its total lumens, beam distance, etc is superior. One way I like to think about it is like this: Cars, HP, and MPG. Just because one car has more HP than the next doesn't necessarily mean that it has a lower MPG. Some cars that have a low HP rating may be terrible at MPG. While a 436 HP 2011 Corvette may get 25+ MPG on the HWY.
Bottom Line: I suggest comparing lumens to lumens, as long as the two lights being compared have the same ANSI FL1 specs.
There is no direct proportion/formula. The newer standard appears to be lumens. Used to be candlepower years ago. Since the power management/efficiencies of different lights, bulbs, LED emitters, etc vary so much, watts can't always be considered a reliable barometer. One light may advertise 5 watts! While a different light may only use 2-3 watts, but its total lumens, beam distance, etc is superior. One way I like to think about it is like this: Cars, HP, and MPG. Just because one car has more HP than the next doesn't necessarily mean that it has a lower MPG. Some cars that have a low HP rating may be terrible at MPG. While a 436 HP 2011 Corvette may get 25+ MPG on the HWY.
Bottom Line: I suggest comparing lumens to lumens, as long as the two lights being compared have the same ANSI FL1 specs.
Gregozedobe
Enlightened
Re: Lumens vrs watts
WHS ^
Lumens for total light output (but don't ask for a conversion from candela or candlepower, that gets even more confusing).
Depending on beam pattern of course, for close up work you want a floody, even beam; to see further away you need a tight concentrated hot spot. The other thing to look at is the run-time graph - lots of (un-regulated) lights put out a lot of lumens initially, but quickly drop off in light output as the LED heats up and/or the battery voltage decreases.
If you want to comapare "throw" (light at a distance) then you need to measure lux (at a specified distance).
WHS ^
Lumens for total light output (but don't ask for a conversion from candela or candlepower, that gets even more confusing).
Depending on beam pattern of course, for close up work you want a floody, even beam; to see further away you need a tight concentrated hot spot. The other thing to look at is the run-time graph - lots of (un-regulated) lights put out a lot of lumens initially, but quickly drop off in light output as the LED heats up and/or the battery voltage decreases.
If you want to comapare "throw" (light at a distance) then you need to measure lux (at a specified distance).
JohnnyBravo
Enlightened
gcbryan
Flashlight Enthusiast
Re: Lumens vrs watts
Watts just tells you how much energy is consumed by the light. A 100 W light bulb in your house consumes 100 watts of energy per house. Incan light technology was old technology and didn't change so one 100 W bulb was more or less like another one so it had some meaning not for output but at least for how high your energy bill would be.
LED's are much more efficient and comparing them to incan by their energy consumption makes no sense. It doesn't even make sense to compare LED's to each other that way since the technology is changing.
Lumen ratings are what matter. Some manufacturers think they have to list watts (and bigger is better to some). Eventually they will all be listing lumen ratings as the public becomes educated.
If I have two used Toyota Corolla's and one uses 10 gallons of gas per hour and the other one uses 5 gallons of gas per hour you're not going to pick the one that uses 10 gallons per hour just because it must be better. Talking about watts regarding LED's is just as silly.
Watts just tells you how much energy is consumed by the light. A 100 W light bulb in your house consumes 100 watts of energy per house. Incan light technology was old technology and didn't change so one 100 W bulb was more or less like another one so it had some meaning not for output but at least for how high your energy bill would be.
LED's are much more efficient and comparing them to incan by their energy consumption makes no sense. It doesn't even make sense to compare LED's to each other that way since the technology is changing.
Lumen ratings are what matter. Some manufacturers think they have to list watts (and bigger is better to some). Eventually they will all be listing lumen ratings as the public becomes educated.
If I have two used Toyota Corolla's and one uses 10 gallons of gas per hour and the other one uses 5 gallons of gas per hour you're not going to pick the one that uses 10 gallons per hour just because it must be better. Talking about watts regarding LED's is just as silly.
Re: Lumens vrs watts
The lumen per watt of common and not so common light sources:
Typical incandescent 60W at ~17 lumen/watt
Typical 20W CFL (compact fluorescent): 60 lumen/watt
Cree XML U2 bin: 160 lumen/watt at 700mA and around 100 lumen/watt at 3A
High pressure sodium arc lamp used in street lighting: 120 lumen/watt
Metal Halide: ranges from 70-100 lumen/watt
Short-arcs: 30 lumen/watt
5mm LED: 20-30 lumen/watt
The lumen per watt of common and not so common light sources:
Typical incandescent 60W at ~17 lumen/watt
Typical 20W CFL (compact fluorescent): 60 lumen/watt
Cree XML U2 bin: 160 lumen/watt at 700mA and around 100 lumen/watt at 3A
High pressure sodium arc lamp used in street lighting: 120 lumen/watt
Metal Halide: ranges from 70-100 lumen/watt
Short-arcs: 30 lumen/watt
5mm LED: 20-30 lumen/watt
