It still boggles my mind when I read some of the posts on here regarding throw distances. Take this thread for instance:
A claim on there of A60s throwing over 400m stock and another light at 700+m. Are we talking meters or feet??? What determines exactly where the ‘throw’ ends? I suppose if I draped up a 50x50 foot sheet of 3M Scotchlite I might say those numbers are accurate. As I posted in another thread I was disappointed in the A60 as my modded C8 killed it. I have an aspheric with a de-domed XP-G2 at just over 3A and it will out throw my C8. But I wouldn’t say it throws 400 or 500m.
I might be the one totally off here which is why I’m asking this question. How are throw numbers determined??
Throw is how far you can see by the light. More precisely, it is the distance at which it can illuminate a surface perpendicular to the light to a certain brightness. These are not all the standard words, but I hope you get the idea.
Since light intensity decreases as the square of the distance, throw is proportional to the square root of the brightness of the beam. By a slightly simplified model of a focused light, it is proportional to the diameter of the aperture or the window and to the luminance or surface brightness of the LED die.
I expect others to add to this.
I think there is quite a bit of exaggeration that goes on too. Sorta like the Chinese lumens ratings. I have several of the great throwers and I’m not sure I’d say any of them hit 800 meters. Even looking at high quality search and rescue lights few state over 500 meters.
There are many variables but I think a big one is total darkness. 800 meters in a city/suburban area is much more difficult than out in the middle of nowhere. I don’t want to call people liers because I don’t think that is the case, but judging distance over 400 meters is very very difficult by eye.
I could try to explain it but this is better, in particular the last paragraph.
The United States Army former standard MIL-F-3747E described the performance standard for plastic flashlights using two or three D cell dry batteries, in either straight or angle form, and in standard, explosion-proof, heat-resistant, traffic direction, and inspection types. The standard described only incandescent lamp flashlights and was withdrawn in 1996.
In the United States, ANSI in 2009 published FL1 Flashlight basic performance standard. This voluntary standard defines test procedures and conditions for total light output, beam intensity, working distance, impact and water resistance, and battery running time to 10% of initial light output. The FL1 standard gives definitions for terms used in marketing flashlights, with the intention of allowing the consumer to compare products tested to the standard. The standard recommends particular graphic symbols and wording for the product package, so that the consumer can identify products tested to the standard. Testing may be carried out by the manufacturer itself or by a third-party test laboratory.
The FL1 standard requires measurements reported on the packaging to be made with the type of batteries packaged with the flashlight, or with an identified type of battery. Initial light output is measured with an integrating sphere photometer, 30 seconds after the light is switched on with fresh (or newly charged) batteries. The total light emitted is reported in lumens. Luminous intensity is determined by measuring the brightest spot in the beam produced by the flashlight, in candelas. Since this is a measure of all the light emitted in a solid angle (the “cone” of light in a particular direction), the beam intensity is independent of distance.
The working distance is defined as the distance at which the maximum light falling on a surface (illuminance) would fall to 0.25 lux. This is comparable to a full moon on a clear night. The distance is calculated from the square root of (the beam intensity in candelas divided by 0.25 lux); for example, a beam intensity of 1000 candelas produces a working range rating of the square root of (1000/0.25), or 63 metres. The result is reported in metres or feet. The working distance is from the point of view of the user of the flashlight. A light directly pointed at an observer may be visible against a dark background for many times this distance, especially if the observer has night-vision equipment.
the ability of a flashlight to place light onto a distant defined area of surface, i.e how well the light is collimated. The throw of a light source of fixed power will be defined by the surface brightness of the light emitter, and the shape, diameter, depth, smoothness, and reflective efficiency of the reflector surface. A flashlight with good throw characteristics is called a "thrower" and generally has a narrow beam that is best for illuminating objects at a distance (hundreds of feet). Compare withflood. The ANSI/NEMA FL-1 standard states throw two ways: candela and meters.
My personal opinion: How far can you clearly see an object about the size of (let's say a coyote), on flat terrain? 100, 200, 300 meters? Throwers are overrated, since the human eye cannot clearly see what you are illuminating after a couple hundred meters. Just the bare eye, no magnification. It's just highly overrated, when you say you can see at 1,000 meters with your light. Well, maybe a barn or a huge building, but not much else. What is really usable light, is more what I think about.
A single building can be seen at up to 4km, larger buildings or industrial chimneys at 5km.
1km is sufficient to notice movements of man-sized objects, 500m enough to spot non-moving humans, below that head, limbs, the face, eye line and details of clothing can be discerned at ~400/300/250/150/100m.
Source: G. Buzek Großes Buch der Überlebenstechniken.
I don’t really understand throwers myself, for example how a smaller die improves throw vs a larger more powerful emitter using a deep reflector. Or whether the same rules apply to a recoil thrower.
The measurement of “throw” is a bit of a cheat, unless you are lighting a newspaper for someone holding it, the newspaper lit by 1/4 lumin at 500m can’t be seen by the person holding the light, it has to be lit enough to reflect and return that same 500m, you can’t even say halve the distance because you are trying to see reflected light
Find somewhere local(ish) with 500m of space, use google earth/maps to measure the distances (between trees/buildings) and then you know its true throw, in the conditions you use the light.
Some good answers woth lots of detail here. Throw is basically, the distance at which the subject receives 0.25 lux or equivalent to a full moon.
How far and with what detail can you see by the light of a full moon? This is where the comments about the limits of human vision and discernible object size and colour come into play.
Light pollution, pollen and other air particulates, and back scatter from the spill portion of the beam will mean that you will never realistically "see" anything useful at 400m from a light "rated" at 400m throw. (A perfectly moonless night on a dark plain with no air-pollution and a spotting scope perhaps?)
The published standards used to advertise throw are just a pre-defined basis for comparison. If measured and published accurately they will give you some idea of how one light compares to another. Of course so many manufacturers just completely inflate the figures that in many cases any claims are totally irrelevant anyway.
For a pure thrower the beam from an aspheric light is probably the best example with which to guage how far you will be able to see at any given rating. Aspherics tend to lose a lot of light in transmission through a big, thick lens, but they have the advantage of not producing any close-up spill which can interfere with your night vision. However the practicality of such a light for anything but the most specialised purposes is debatable. The beam profile is usually so small as to be almost useless for most practical applications.
A reflector light which is described by users as a thrower will endeavour to have most of the light concentrated in a small area towards the centre but there will always be a certain amount of spill escaping to the sides and the close-up effect of this will ultimately affect how far you will see with the main part of the beam.
I find that for me, the best way of judging the usefulness of is light is to try it in the field or else, look for some quality beamshots photographed by users with manual control of their cameras. Luckily, we have a few people here at BLF (and other flashlight sites) that have both the inclination and ability to post these. Even then, I find the best reviews are those showing beamshots from several different lights, taken in the same location and under the same conditions.
I for one, don’t think that the accepted standard for testing ‘throw’(0.25 lumens) is that meaningful (real world use), apart from establishing a benchmark for testing purposes.
For example, a light that is rated to throw 500m is able to put 0.25 lumens at a distance of 500m (obviously). But at that distance, one would need a pair of binoculars, or a ’scope to be able to make out the small details.
Fact is, the light losses through the optics (of the binos or the telescope) are considerable, and that would negate the ability of the flashlight to meaningfully illuminate the target at that distance.
My best thrower is rated (at 0.25 lumens) to throw 550m. But believe me, at that distance I’m not able to make out much of anything (I’m using a Nikon 10x50 pair of binos). So I would say, from experience, that my light is good up to about half that distance.
Light that is "thrown" is typically light that is reflected straight forward once, using the reflector of the flashlight.
If the reflector has a perfect parabolic shape then all light from the theoretical focus point will be reflected straight forward. This is an ideal thrower.
However the LED is not a theoreticial point light source, and the reflector is only almost parabolic. This means that the light will not be reflected straight forward. There will be some small divergence. If this divergence is small, and a large percentage of the LED output is reflected in the parabolic reflector, then the flashlight is said to be a good thrower. Some light is not reflected at all or is reflected more than once. This is "spill". The focus may be intentionally very bad, then the flashlight is a flood flashlight.
Using a deep reflector more of the LED output can be reflected. The divergence can be reduced by having a large reflector in relation to the LED size. Or a smaller LED size in relation to the the reflector size. This is why you sometimes may get more throw using a smaller LED than with a larger LED with higher total output.
An LED that is smaller but otherwise identical will give more throw because it cools better. To reach a given junction temperature, it will take more current per area because it doesn’t heat up the metal under it or the air over it as much. Throw depends on the light output per area, not on total light output.
The spill from a really bright light will just about blind you, so I doubt that blinding spill you will let you see anything at a distance with 0.25 lux. It’s measurable, but I’m not sure it is all that meaningful. But you have to have some measure. If you were lighting up things above you with no reflection from anything closer, you could see a drone or something at that distance probably, like a spotlight picking out airplanes. But imagine trying to use a spotlight in a forest.
What is not is the humans perceiving those standards. Age, smoking or non smoking (smoking severely reduces the eye's ability to enlarge the pupil while at the same time reducing the sensitivity of the photoreceptors in the eyes) and ambient light.
Where I live the biggest disturbance to throw is dust/fog/mist in the air.
If your cannot determine whether you are looking at a dog or a cow at 400 meters at noontime then no flashlight can make you see it at night.
To me throwers are the best because I hate when there is too much light. And I perceive floody lights as putting too much light on the objects close to me.
A well tuned thrower will put most of the light far far away. And lower modes let me use it for anything. Most of my tasks at night is done in the spill of a light.
My home is often described by visitors as cosy and cave like. I do not have much light on by any standard. Not even my own :-)
So however we try to standardize things we are not standardized ourselves.
Appreciate all the replies. So, what I gather from the above is that the angle of the dangle is proportional to the heat of the meat, or something like that. Seriously though, throw to me was a nice lit up hot spot at a distance, but supposing it is measured at .25 lumens, well that makes a big difference. Thanks again.
I know that when shined at a light gray or white target some of my lights are visible 50-70% further than the numbers suggest. I know that is because of the higher reflectivity of the surface, but it gives me confidence in the calculated values on a less reflective surface are legitimate. I have tested lights that range from a few thousand candela, to one making almost 380,000. I verify distances with Google maps when testing outdoors. 300,000 candela (uniquefire uf-1405, dedomed XP-G2, LD-4B driver @ 2.4A) was visible off a white/Light Gray water tower (keep in its a relatively reflective surface) at 1700 meters. The numbers say it should be .25 lux at 1095 meters.
Even the Uniquefire t20 lights I modify consistently put out over 100,000 candela. That’s a lot of throw in a small package.