Why can't LED match incandescent in throw?

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Obviously, comparing the two with similar total outputs. There are some that seems to have about the same size beam center diamater at close range, but when you shine them far away outdoors, the incandescent always outthrow the LED.

Why is this?

Luxeon I (not overdriven) struggles to match the throw of even a 2D/2AA cheapie flash light.

My 1W 3AAA task force is no match to my 2AA 99 cent cheapie fitted with a 2.4v 0.9A xenon PR bulb throw wise.
 

CLHC

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Good question. But I need my memory refreshed again regarding this since it has been discussed before. :popcorn:
 

McGizmo

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There are some that seems to have about the same size beam center diamater at close range, but when you shine them far away outdoors, the incandescent always outthrow the LED.
bold italics added for emphasis.

IF the beam angle is the same and IF the output of light, in the colimated portion of the beam is similar then the effective range of the two sources would be similar. In cases where the incan and LED have similar flux but the incan throws further, I suggest that the incan has more of its output in the reflected beam and or it is a tighter beam angle.

~or~

Photons from LED sources are anemic and they get tired quickly and fall to the ground instead of hitting the target and returning to your eyes with photonic news. :nana:
 

jsr

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I'm interested to know too. I likely haven't been around long enough to have seen the previous discussions on this, so I hope no one minds rehashing this topic.
 
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McGizmo said:
bold italics added for emphasis.

IF the beam angle is the same and IF the output of light, in the colimated portion of the beam is similar then the effective range of the two sources would be similar. In cases where the incan and LED have similar flux but the incan throws further, I suggest that the incan has more of its output in the reflected beam and or it is a tighter beam angle.

~or~

Photons from LED sources are anemic and they get tired quickly and fall to the ground instead of hitting the target and returning to your eyes with photonic news. :nana:

Light from white LEDs isn't inherently white, but its blue light mixed with yellow light as to appear yellow, so it is rich in shorter range blue.

Does the different spectrum affect the throw due to a difference in diffusion or attenuation in longer range?
 

Brighteyez

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In your two cited comparisons, put the two lights side by side and determine which you prefer. That should clarify things for you. Insofar as throw, a lot of that has to do with the reflector as well.

Or to take another comparison of closer proportions, putting a 3D Mag with a Xenon bulb alongside a LEDBeam 3C will have the 3D Mag as being the throw king, but I think anyone that puts the two side by side will perfer the output from LEDBeam 3C (even the mainstream consumer.) It should also be noted though in this example, if the Mag were focused to a larger hotspot to come close to equalling the hot spot from the LEDBeam 3C, it would probably lose in the throw race.

But I think the answer to your question is simply one of "we're not there, yet" in the state of LED technology. That's why your folks have you in school, so that your generation can advance that technology and make things like filament bulbs obsolete one of these days.

Handlobraesing said:
My 1W 3AAA task force is no match to my 2AA 99 cent cheapie fitted with a 2.4v 0.9A xenon PR bulb throw wise.
 

McGizmo

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Would a LED throw better in a vacuum? There are comments that would seem to support this. I for one don't know. In our atmosphere, it does seem that the red end is less diverted than the blue end but it is beyond me and my ken. There have been numerous threads relating to the incan's superiority in outdoor target illumination and much has been said about the nature and color of the target. If the target is white, will the LED do a better job outside than if it is brown? I would think so but to what extent does the incan have better reach than the LED due to its spectral composition, I simply do not know.

I would expect that if you were at the bottom of the ocean and an incan and LED were aimed at you from topsides that the LED might appear brighter even if the beam pattern and flux were the same for both sources.

You have qualified blue as shorter range. In what cases is blue "shorter range"?

It seems that blue light will be deflected by particles whereas red light will be absorbed by them. For a round trip from your source and then back to you, which is more likely to return and does this depend on the type of particles in the way? :shrug:
 

bjn70

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I'm not convinced that incandescent has an advantage.

My best small lights are a Pelican M6 LED and a new Streamlight TL-2 LED. I also got a used Streamlight Scorpion incandescent recently. In my backyard aiming at the fence about 100 feet away, both of these LED's outthrew the incandescent.
 

Double_A

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I posted this a few weeks ago on the topic of SF incandescent lamps. I think it's appropriate to put some perspective on the durability of quality incandescent lamp assemblies, the heart of any incandescent flashlight.

...............

Surefire E2e Lamps, finally one burned out!

There is always alot of talk about how long Surefire Lamps last. From my experience a LONG time.

Here is a story some of you might be interested in and some background info.

I am a supervisor of an Environmental Safety & Security team at a large Semiconductor Company. We have a team of eight Security Coordinators and another 20 Emergency Response team members. We respond to Medical related incidents and Hazmat Incidents.

A little over three years ago I convinced the campany to dump the 3D cell Maglights we'd been using and buy the eight Security coordinators & myself Surefire E2e flashlights. (I didn't take much convincing when the facts and need was laid out.)

Today in the three years these nine E2e's have been in constant use, I replaced the third lamp.

Two of the three lamps were damaged by the same guy who is always dropping his E2e from a height, when turned on.

But today was special, one of the guys(night shift) finally burned a lamp out!

Crazy as it sounds I finally said too myself FINALLY we burned out a lamp from use!

One out of nine over a three year period.

Double_A
__________________
 

Planterz

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One thing that we have to remember is that the "white" LED is a rather recent invention. The first "white" LEDs are a result of "filtered" blue LEDs, invented by Nichia. This was in 1993. White LEDs now more commonly combine blue and yellow diodes to produce "white" light. This started in 1996. Lumilids invented the Luxeon in 1999, and this is what really made the LED flashlight a viable replacement for incandescent bulbs in some applications. The first Luxeon powered flashlight was the Arc LS in 2001.

So, white LED technology is really only about 10 years old. The "high power" LED flashlight is only about 5 years old. The incandescent light bulb however has a good 100+ years head start. Even in flashlights, the incandescent light bulb has several decades head start. LEDs aren't a do-all replcacement for incandescents yet, but give them time. Within the next decade or two, LEDs will likely replace house lighting, car headlights, etc. Might be a while before they replace HID applications though.
 
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gadget_lover

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The assertion that an LED light does not throw as far as an incandescent of the same power is invalid. It's a matter of having the proper reflector AND the color tint that reflects the best.

Yellow incan against green shrubs looks brighter than a bluish tinted led. Shine them against a white building and the LED will seem brighter.

Most LED lights have small reflectors or optics and are designed for a usable beam (fairly wide).

This series of shots are of a D cell mag head on a minimag with a Lux III . The tree is about 300 feet from my back porch.

The light;
turbomm10.jpg



The beam is 18 inches across at 25 feet.
turbomm8.jpg




The tree
turbomm11.jpg




The tree lit by the Lux III from 300 feet away.
turbomm12.jpg



So you see, you can get throw.

Daniel
 
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bjn70 said:
I'm not convinced that incandescent has an advantage.

My best small lights are a Pelican M6 LED and a new Streamlight TL-2 LED. I also got a used Streamlight Scorpion incandescent recently. In my backyard aiming at the fence about 100 feet away, both of these LED's outthrew the incandescent.
I don't know the specific lights but the real point is, are these two lights of comparable total output?

When you do a ceiling bounce test, do they illuminate the room to approximately the same perceived brightness? I'm only comparing LED and incandescent lights of similar output.
 

asdalton

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Incandescents are a more intense light source (more light flux per area on the emitter) and are easier to focus for that reason. Given equal reflector sizes, an incandescent lamp will throw better than an LED. (The Luxeon V is very large and particularly difficult to focus well.) You can always give the LED an advantage by using a larger reflector, though.

I consider an LED flashlight to have decent throw once it reaches the performance of the Surefire E1L.

The throw of an LED is very good if it can match or beat the Surefire E2e (in throw, not lumens), which is basically a minimum bar for the "tactical" throw range. Very few small LED flashlights perform this well. The Aleph 1 and Pelican M6 3W are 2x123A LED flashlights that do.

Going beyond this, you can get excellent throw by putting an LED in a large, smooth reflector in the Mag C/D size range. The Dorcy 3D and the Ledbeam 3C have this type of design. Of course, what I said earlier still holds; you could get even more throw by putting an incandescent lamp in those same large reflectors.
 

enLIGHTenment

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I just ran a statistical analysis on the center beam lux (throw), overall output, and light source type data for all the lights listed on Flashlightreviews. From the entire data set, beam lux is most heavily dependent on overall output, followed by reflector/optic design, and only weakly dependent on light source type.

All else held equal, lights of equivalent output and reflector efficiency will have close to the same throw regardless of if they use bulbs or LEDs. Where LEDs fall down is in that matching brightness with the typical incan means going to a Lux V, which is too big to focus well. Heavily overdriven Lux III lights will stand up with some of the best incan offerings. The Striker-VG, for instance, will out throw 93% of all lights reviewed on FLR--incan or LED--while using an optic that's smaller than a Mag D head. LEDs really hold their own in reflector efficiency. Indeed, half of the top six lights for reflector efficiency (most throw for least overall output) are LEDs.

The bottom line is that if you want throw, you need a very bright source with a small surface area and a narrowly focused optical system. LEDs already have narrow optics so the only obstacle is the lack of high-power single die emitters. Heavily overdriving a Lux III will give very good throw now, but for reliability and runtime it's probably best to wait for K2 or XLamp based lights.


Here's the regression analysis for anyone who's interested:

clipboard019xb.png


TORatio is the ratio of lux to overall output. It is essentially a measure of reflector efficiency.
 

Phaserburn

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You have to remember that leds are emitters; that means they are projecting the majority of their output forward, missing the reflector with much of it. This is why optics are used instead. An incan filament output is close to 360 degrees, collecting most of it in the reflector. You can improve the led throw somewhat by altering the reflector geometry, and by getting a non-high dome emitter. This is why side emitters throw farther in Mag reflectors than high domes do. Most of their output is to the sides, hitting the reflector, which is what creates throw.
 

BigHonu

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As others mentioned, I think the issue is finding the right reflector. No reason why an LED of equal output with an incandescent source shouldn't be able to get as much light out on an object.

How much information that light returns to the observer is a different story.
 

Builder

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The simplistic answer to why a LED have less throw than incan is something known as the "inverse square law".

It's covered in High-school physics and it's simply, "double the distance, and quarter the brightness". In the texts, it is usually qualified with "only applicable to point source".

When the radiating body is NOT a point source of radiation, there is something known as "conservation of radiation", which is easily demonstrated by lighting a room with a bare lightbulb, and walking away until the "glare" is comfortable to our eyes. Now replace it with a frosted bulb (which distributes the output over it's entire surface) of the same wattage and stand at the same spot as before. Even though it is now "softer", our eyes wll receive greater intensity at the distance where the naked bulb "point-source" starts weakening.

There is a "Rule of 5" which states that up to 5 times the diameter of the radiating body, light does not obey the Inverse Square rule, instead it only decreases by 1/2.

To take advantage of this, flashlights use big reflectors - to maximize the radiating surface. Most of us know this already - over distance, a larger reflector will ALWAYS outperform a smaller one, given similar lights.

Big reflectors don't help LEDs as much - they don't have the full 360 degree radiation for an even beam, and optics loses even more energy. But worse, because it is virtually a point source, its light is already diminished by the time it reaches the reflector. In comparison, the filament in the incan bulb has a much larger radiating surface, so it can enjoy the 'conservation of radiation" further.

In general, the best light reflectors will have a radius of no more than 5x the filament length.
 
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jashhash

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Perhaps light in the red spectrum is better able to pierce our atmosphere than blue light. Reason being is that our atmosphere is slightly bluish in hue. If you, for example look at far away mountains they always look much bluer than when compared to the foreground the reason being is that the atmosphere is blocking and reflecting back blue light. This combined with the large die size of the emitter, combined with the fact that LED's project most of their light forward are all contributing factors.
 

Dustin Liu

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IF the beam angle is the same and IF the output of light, in the colimated portion of the beam is similar then the effective range of the two sources would be similar. In cases where the incan and LED have similar flux but the incan throws further, I suggest that the incan has more of its output in the reflected beam and or it is a tighter beam angle.

~or~

Photons from LED sources are anemic and they get tired quickly and fall to the ground instead of hitting the target and returning to your eyes with photonic news.
 

EV_007

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Sounds like a combination of radiating surface area and the scattering of the blue wavelength accounts for the incans ability to out throw and resolve better detail to the human eye. I think the last two posters seem to make sense the most.

I like the "blue mountain" analogy. In photography, a warming filter such as a skylight or UV tends to increase contrast over non-filtered images due to the scattering of the blue wavelengths. Also the reason red light does not ruin our night vision may be correlated to this as well? In black in white photo printing, the yellow, orange and red filters seem to yield most contrast and clarity.

Maybe that's why incans cut though fog and rain better than LEDs, more surface area that scatters the blue wavelengths? Also why incans do a better job of cutting through tinted glass than LEDs? Maybe bluish tint scatters the LED and not the yellowish light of the incans, which are closer to the red spectrum? I wonder if a orange filter over the LEDs would solve that problem, or is it more to do with the wider spectral characteristics of the hot incan bulb. Notice that an incan in the eyes "seems" hotter than LEDs, even from a distance?

HID headlights look cool, but suck due to the sharp contrasty light fall off, not to mention the "blue" haze?


Just my .02 cents.
 
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