Why don't LED's have as good a throw as incandescents?

LED's put out more light for less current compared to incandescents, so why don't they throw as good? It seems they are starting to get LEDs to throw, but they're still far behind other options like Xenons and HIDs. Why is this?

Less lumens and less concentrated beams means less throw, it's as simple as that. Btw, I have LEDs that outthrows some incans (e.g. my HD45 outthrows my SF A2).

Sigbjoern

LED don't scale up well. Incandescents do scale up well, but not down. So for a dim torch you want an LED, and for a bright one you want incandescent. The switching point varies as LEDs improve, but I think it is currently around 60 to 100 lumens. If you want really good throw you need a really bright light which means incandescent.

The other issue is beam colour. The colour depends on the wave length of the light, and different wave lengths get reflected differently by different sizes of dust particle. If you want a beam that will cut through fog, dust etc (which is what people sometimes mean by "throw", ie in poor conditions), then incandescents seem to work better because they have less blue/white colour.

Torches which use LEDs are often designed as flooders because that is what LEDs are best at.

A 27mm / LuxIII light will outthrow the SF E2e with the same lumens and longer burntime and is only slightly larger ...
It has only taken some time to learn how to properly focus a LED. They can throw just lke incans.

BUT ... this depends on the size of the lightsource itself, and for example the LuxV with its 4 dice is significantly larger than the usual Xenon lamp, to it is more difficult to focus, which is why you see bigger and deeper reflectors with those LEDs --> L5, L6, U2, ...

bernie

Brangdon said: "...LED don't scale up well. Incandescents do scale up well, but not down. So for a dim torch you want an LED, and for a bright one you want incandescent...."

That is a good general principal. There is no single LED now available (or soon to be) that can beat a high output incandesent bulb. Ironically as LEDs are pushed harder they become more like incandescents -- high heat and much shorter emitter life.

OTOH you can cluster LEDs in the same form factor as a single incandescent and sometimes get competitive output. E.g, the Elektrolumens Tesla-6 produces 432 lumens in a 3D Mag body: http://elektrolumens.com/Tesla-6/Tesla-6.html

It is possible for an LED light to produce output and throw roughly competitive with an incandescent for a reasonable price. E.g, the LEDBeam produces DOUBLE the output of a 3D Mag and almost the same throw. Only $25, free US shipping:

http://www.ledbeam.com/
http://www.flashlightreviews.com/reviews/ledbeam_3c.htm

to get throw you want to have a point souce of light. LEDs have greater light emitting surface area than incandescent lamps do, so they are going to put out more of a flood light.

My KL3 outthrows all my incandesents, but it's total lumen output is like five times less. I think the way the beam is focused determines throw more than anything.

I don't hink deeper reflector brings more throw. Only wider reflector brings more throw (after playing around with some light modeling softw.)

I think there's a point missing here. LEDs are emitters; that is, they are aiming the majority of their output forward, therefore missing the reflector with much of it. An incan bulb radiates light in close to a 360 degree arc, making maximum use of a reflector. Incan lights are gathering more of the output and focusing it into the beam, throwing farther.

Phaserburn said:

I think there's a point missing here. LEDs are emitters; that is, they are aiming the majority of their output forward, therefore missing the reflector with much of it. An incan bulb radiates light in close to a 360 degree arc, making maximum use of a reflector. Incan lights are gathering more of the output and focusing it into the beam, throwing farther.

Click to expand...

Yep. The focus of a reflector is not at the bottom it is some point above it. Which is just fine for an incandescent light bulb where the filament is up in the middle of the lamp. Theoretically that filament should be placed at the focal point for maximum throw.

You can't do this with an LED. The die is attached to a heat sink surface at the bottom and emits light from only one surface such as Phaserburn refers to.

IIRC it's the Pelican that make the "Recoil" which places the LED emitter up front with the lens and aims it BACKWARDS toward the reflector.

If you could make an LED "Lamp" with five LED die arranged like a cube positioned up above the base on two stub wires like an incandescent lamp you might have a killer LED light.

Double_A

In addition to the above, a basic factor in determing throw is the divergence of the beam, which is a function of several things, including the ratio of the exit aperture diameter (e.g. reflector) and the size of the source.

Incandescent sources typically emit their light from a relatively tiny filament and LED's emit from a very large area of several semiconductor dies, so LED's start out disadvantaged for a given reflector/lens size.

That said, there are some clever tricks to make up for this, like Total Internal Reflection (TIR) optics. My L1 has a surprisingly good throw compared to my A2, for example.

The best thowing light I own is my Mini-HID. The reflector isn't particularly big, but the light is emitted from a very tiny spot of ionized gas in the bulb, so the beam divergence is very low.

Cheers,
Bob

I have to admit my EL-Blasters given cell for cell comparison
out throw my incandescent Mags, even my LED modded Mag
kills the standard incandescent Mag, my minimag is much brighter than it
was before since I put in a Terrulux TLE-10 mod .5 watt

This is a very interesting thread!

I've been wanting an LED that would throw decently and now that the Streamlight ProPoly 4AA Luxeon is out, I've got one! It does have a long and deep reflector which seems to produce a very nice, tight, good throwing light with useful sidespill.

I was using the UK 4AA w/switch and running the "rechargeable lamp" with NiMHs. It threw really well while being compact and using common AA batteries. But... my wife knocked if off the counter one day and... goodbye $10 lamp. The $10 is one thing, but what if I was camping or hiking and it got dropped? Now I have my ProPoly and (ironically) my wife dropped that one too. But no worries! The LED just kept on producing nice, clean white light!

I'm pretty happy! A more compact light with really great throw would be nice, but it is hard to justify spending more than the $22 my ProPoly cost me!

ALso, I think it might have to do with the fact that LEDs' are missing the entire infared spectrum. I think this might cause LEDs' to not have as much "fill" as incans and therefore seems a little "weak" in comparison. I don't know if I just coined that "fill" phrase and idea but it seems reasonable to me, unless I'm missing something.

Throw is going to be a function of surface brightness of the light emitting surface, reflector size (which is going to include depth), and total output of the light emitter.

For a given reflector size, and given an optical design optimal for the light emitter, surface brightness of the emitter is going to be the prime determinant of throw.

A light emitter of higher total output and emitting surface area, but lesser surface brightness (e.g. a LuxV compared to a LuxIII) can achieve equivalent or greater throw, but it will require a larger reflector to properly collimate the light.

Hehheh, my LED's have awesome throw when I point them down the barrel of my 16 inch newtonian reflector telescope!

Hmmm....

My best "throwing" LED lights all have fairly deep and not too big reflectors...

Best being Dorcy Metal Gear 3D, second being Streamlight Pro Poly 4AA and third EverLed HD in 2D M*g with 3C.

Honorable mention to Inova X0, but it's all throw with little spill and I don't favor that arrangement...

Point being I THINK... that 1W LEDs in properly selected reflectors throw just peachy!

Because LEDs are not a point source I'm convinced that the fresnel lens is the best solution. With just a kerosine lamp a lighthouse can throw 20 miles or more.

(Which is the only time "Can be seen from 20 miles away" makes sense to me.)

BobVA said:

The best thowing light I own is my Mini-HID.

Click to expand...

I've heard of HID's, but I've never heard of a "Mini-HID". What brand of light is that? What kind is it?

A lot of LED flashlights underperform compared to what they could do, if their reflectors or optics were better designed. For example, the use of a strongly textured reflector with a Luxeon makes the beam only marginally smoother, but it kills the throw of the beam. The Streamlight ProPolymer Luxeon flashlights get a lot of throw with their smooth reflectors, and the beam artifacts are only minor.

I recently got an Aleph 1, and I am amazed by the amount of throw that it gives with a Luxeon and only a 27 mm reflector. Previously, I had guessed that the BugOutGear 3W module was somewhere near the theoretical limit for the amount of throw that a Luxeon III could produce with that size of reflector. However, the Pelican M6 3W throws considerably better, and the Aleph 1 throws better still.