Comparing LED lumens to Incandescent bulbs - AVS Forum
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post #1 of 13 Old 06-05-2010, 11:22 AM - Thread Starter
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Is it true you can't compare them? I read that LED lumens are brighter at the same lumens rating on a Incandescent bulb.
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post #2 of 13 Old 06-05-2010, 11:40 AM
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The watt is a unit of power. This power is not a measure of the amount of light output, but rather indicates how much energy the bulb will use.

A 60 watt incandescent bulb and the 15 watt compact fluorescent can both provide 900 lumens.

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post #3 of 13 Old 06-05-2010, 01:02 PM
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Quote:
Originally Posted by bruce banner View Post

Is it true you can't compare them? I read that LED lumens are brighter at the same lumens rating on a Incandescent bulb.

Lumens are measured in a way that takes into account all angles so they wouldn't change, 100 lumens is 100 lumens. Of course you can have different amount of lumens in a certain area you would refer to the unit as candelas (light output at a certain angle).

The benefit of LEDs is that they put more light where you need it. Incandescents are so good because they output a lot of light at a lot of angles but if you need a certain area lit then you need to reflect more light which means more loss. As a result 100 lumens from a bulb will appear to be much less than 100 lumens from an LED when aimed at a surface.

Speaking in terms of projectors, LEDs are better than bulbs because more light is output forwards and as a result less light output is lost (reflectors aren't 100% efficient). I'm not sure how lumens are measured for projectors but I would guess at the bulb so the light output from say 2000 lumens from an LED would appear brighter than 2000 lumens from a bulb.
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post #4 of 13 Old 06-05-2010, 01:13 PM - Thread Starter
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So you're saying Incandescent bulbs have a more focus light output while LEDs are spread more evenly?
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post #5 of 13 Old 06-05-2010, 02:10 PM
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What you are probably referring to is the HK effect (Helmholtz-Kohlrausch) where there is a perceived increase in brightness with saturated colors. Lasers and also LEDs can produce very pure colors, where as with bulbs a single color is usually more a mix of large amounts of one color (ex: red) but smaller amounts of other colors as well.

Just a guess but our brain is always averaging sensory data. With a bulb you would get red but also some other colors, so your brain averages the color value as a darker red. With LED there is more red and less of the other colors, so the averaged value is a brighter red.

After spending considerable time with Microvision's SHOWWX laser projector, I can tell you that the HK effect varies a lot with content. With movies like Sherlock Holmes or Brothers, it really felt like a dim 10 lumens. But you play certain scenes of the Speed Racer blu-ray, or colorful animation, and suddenly those 10 lumens seem a lot brighter.
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post #6 of 13 Old 06-05-2010, 06:17 PM - Thread Starter
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Quote:
Originally Posted by Sisyphus View Post

What you are probably referring to is the HK effect (Helmholtz-Kohlrausch) where there is a perceived increase in brightness with saturated colors. Lasers and also LEDs can produce very pure colors, where as with bulbs a single color is usually more a mix of large amounts of one color (ex: red) but smaller amounts of other colors as well.

Oh I see.. This is what they mean by "pure white" when referencing LEDs?
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post #7 of 13 Old 06-06-2010, 02:21 AM
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Quote:
Originally Posted by bruce banner View Post

So you're saying Incandescent bulbs have a more focus light output while LEDs are spread more evenly?

Other way around. LEDs can put out light in a very tight angle where incandescents put out light in 360 degrees (even though the base blocks some light the filament is still producing light in that direction).

You still might need a reflector for the LED but it needs to reflect much less light and as a result the whole system is far more efficient than incandescents for spot lighting.

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Originally Posted by bruce banner View Post

Oh I see.. This is what they mean by "pure white" when referencing LEDs?

Pure white in terms of LEDs is just a grouping of a white tint. You can have different types of white and LEDs are usually offered in three bins of white.

There's warm white, neutral white (or pure white I guess) and cool white.
Warm white usually has the highest CRI, looks the most yellow and is usually the least efficient (lumens/watt)
Neutral white is in between
Cool white usually has the lowest CRI, looks the most blue and is usually the most efficient (lumens/watt)
* A light source with a lower CRI will make it harder to tell colors apart (like those nasty sulfur bulbs they use in some street lights that make everything orange-yellow)
Warm white is what you would normally use in your home because the color (closer to incandescent) and higher CRI makes it easier on our eyes.

Anyways I think what he's talking about is that let's say for example you want red light from a bulb you would need a filter that blocks out every other color than red but since they aren't 100% you won't get a pure red because they will allow a little of other colors to pass as well. With LEDs you can get an LED that outputs only red so you get a more intense/pure color.
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post #8 of 13 Old 06-12-2010, 01:30 PM
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led and incandescent light sources can be compared directly because their output is stated in photometric units: lumens. Say you have a projector with a red ,blue , green led it will have a lumnen output at a working temperature of 6500 and it can be compared directly with a white light source with filters.
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post #9 of 13 Old 06-12-2010, 02:31 PM
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I have can lights in my house and I just replaced the incandescent with the homedepot fluorescent. It said on the box 14 watts is the same as a 60 watt incandescent. In my opinion they look a lot dimmer.
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post #10 of 13 Old 06-12-2010, 02:54 PM
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Quote:
Originally Posted by Sisyphus View Post

What you are probably referring to is the HK effect (Helmholtz-Kohlrausch) where there is a perceived increase in brightness with saturated colors. Lasers and also LEDs can produce very pure colors, where as with bulbs a single color is usually more a mix of large amounts of one color (ex: red) but smaller amounts of other colors as well.

During the development of DLP cinema projectors Texas Instruments changed the red primary filter they used because it caused the Helmholtz-Kohlrausch effect. The Helmholtz-Kohlrausch effect also known as chromatic luminance is apparently undesirable with a display. The HK effect is stronger in some hues than in others and the effect varies significantly across viewers, quite strong in some and nearly nonexistent in others. It causes substantial additivity failures in brightness matching which violate the basic algebraic rules of trichromatic theory used in displays.

I expect LED lumens and traditional lamp lumens can not be directly compared because projector manufactures are not quoting the same thing. With lamp projectors the figure is often for uncalibrated maximum brightness in high lamp mode with a new lamp and the iris fully open. Once calibrated and not using white peaking or brilliant/vivid color modes and in eco/low lamp mode with a lamp with a few hundred hours on it and the iris at mid way, it is going to be nowhere near as bright. LED lights on the other hand should be more correct - calibrated out of the box and do not dim much with age, they also can use LED dimming instead of a iris, so the manufactures figures maybe a lot more accurate.
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post #11 of 13 Old 06-12-2010, 04:04 PM
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Quote:
Originally Posted by mlang46 View Post

led and incandescent light sources can be compared directly because their output is stated in photometric units: lumens. Say you have a projector with a red ,blue , green led it will have a lumnen output at a working temperature of 6500 and it can be compared directly with a white light source with filters.

Technically speaking yes you can compare lumens directly with lumens but when talking about how bright a lamp is there are so many more things that have to be accounted for. The whole system (reflectors, optics, bulb) will affect the brightness you actually get on the screen. Since projectors require a tighter beam of light, compared to flood lighting for example, wide angle bulbs will suffer against LEDs when you take similar lumens at the light source and compare them to lumens out the front.

I know he asked about lumens, and for that yes you are right. I just don't want someone who doesn't understand well to read this and get the wrong idea.

Quote:
Originally Posted by Bsims2719 View Post

I have can lights in my house and I just replaced the incandescent with the homedepot fluorescent. It said on the box 14 watts is the same as a 60 watt incandescent. In my opinion they look a lot dimmer.

A lot of people buy light bulbs based on their wattage but that is not the way to do it. Unfortunately the incandescent spares I have downstairs ... ones produced by GE, Phillips and Sylvania don't have lumen ratings!

When you go to buy lights you should look for a bulb with lumens that will suit your application and then look for the bulb that takes the lowest watts to accomplish those lumens.

To give you an idea I have:
Greenlite frosted 40W incandescent bulbs rated at 320lumens
Greenlite soft white 60W incandescent bulbs rated at 520lumens
Sylvania Super mini Soft White 13W fluorescent bulbs rated at 850lumens. These are rated as 60W replacements but they are quite a bit brighter than the ones I use (noticeable too) so I'm guessing there are some much brighter 60W bulbs out there (mine are coated as well so that affects the light output).
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post #12 of 13 Old 06-14-2010, 02:15 AM
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Here is a paragraph from a website which gives you some info in comparison between LED vs Mercury Lamp lumen comparison...
.

"LED projector lumen is the video brightness, not lighting brightness. For example a 24W 3-LED lighting projector, it can get 60 lumen video, like iSival's MP720B1. But for a 243W mercury Lamp projector, which claim image brightness is 3000 Lumen. Do you really believe 10 times power consumption can generate 50 times brightness, for mercury bulb? Or LED is only 20% efficiency compare to Mercury bulb? Further More, human eyes have a large adaption range, you will feel 100 lumen LED projector is bright enough to enjoy watching movies, playing games, etc. And LED's spectrum is much better than lamps, LED's light is purer than lamps, so the video is much vivid"

You can get away with lower lumens on LED projector, ti's not a direct comparison..not apples to apples..
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post #13 of 13 Old 06-14-2010, 04:09 AM
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I have a hard time believing the manufactures would not use the same measurement techniques since that is what the public is used to. They are not trying to educate us as to some new means of measuring light output that makes something rated at 100 brighter or just as bright as something rated at 2000. Face it, if they could make us believe that LED projectors are brighter than traditional lamps, they would have a boat load more units on the market.
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