How far can you see compared to ANSI throw rating? - Discussing measurements and real world use

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dave1010
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How far can you see compared to ANSI throw rating? - Discussing measurements and real world use

(Started a new thread as the [Maxtoch X Pro thread](https://budgetlightforum.com/node/77848) was getting derailed)

So, we all know that you can’t see things clearly at the ANSI throw distance that flashlights are measured at. The question is: how far can you see compared to ANSI throw?

If we can get some typical examples to see how this varies at different distances then we’d have a good guide to convert ANSI throw to visible throw.

I’ve heard the rule of thumb “halve the throw to get the visible distance”. But my guess is that it’s not linear.

Background

ANSI FL1 throw is the standard for comparing how far a flashlight beam throws. The distance is how far the light will shine 0.25 lux on to a surface.

That’s about the same lux as a full moon. You can normally identify things nearby on a full moon and it’s bright enough to hike. 0.25 lux is enough to bounce back off a surface (eg a map) and hit your eyes if they’re a short distance away. When a map 1km away from you is lit up with 0.25 lux then someone at the map will be able to read it but not enough of the photons will make it all the way back to your eyes for it to be visible.

Interestingly, this is also about the brightness where our eye’s cones and rods work together and we just start seeing things in color.

Convert candela to ANSI throw by multiplying by 4 then taking the square root. Eg 250kcd (250,000 cd) times 4 is 1,000,000 and the square root is 1000, so 250kcd = 1000m.

Clarifications

  • You should be where the flashlight is, not where the object being lit up is
  • Using mirrors or highly reflective objects (like road signs) is cheating
  • Measurements will vary due to other variables too. It will be interesting to see how much they vary and of they can be averaged.
    • Subjectivity of what is “visible”
    • Eye sight
    • Weather
    • Reflectivity
    • Accuracy of ANSI measurements

General observations from memory or specific measurements welcome. Feel free to discuss other things about throw / candela here too.

ANSI throw (m) Visible distance (m) Info

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I like this, because the ANSI is absolutely useful, but for interpretation purposes figuring this threads main purpose out could be useful for those of us that aren't TOO concerned with on paper numbers, but more about how the light looks while in use. Although, so many factors can change that day to day of course.

 

thanks Dave.

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Distance at 1 lux is a better measurement for visibility.
Keep in mind that the light has to bounce all the way back to you, so its actually traveling 2x the distance.

0.25 lux is realistically only visible by someone standing at the target, or if you’re pointing the light at a bright object like a white wall and there isn’t a lot of moon light or ambient light around.

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ANSI throw rate allows you to compare apples with apples in objective way. What you’ll do with that knowledge is completely different thing, though.

Using 1 lux vs 0.25 or considering 2 x travel won’t tell you whole story anyway, as your night vision is highly affected by spill and, generally, by amount of light in your proximity. And beam shape is not the only factor, but also humidity and diffusion, type of objects illuminated by spill (dark, reflective, leafs moving in the wind and “flashing” etc.), light temperature…

Two flashlights with identical throw rate can give quite different subjective results by spill effect only.

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Although I find myself lighting up dark places for coworkers often (only one that edc’s) I don’t do it from far away.
For inspecting things out of reach, like in lrt tunnels or ceilings in warehouses, if the surface isn’t painted high gloss or at all. I’d say to illuminate something enough to find a roof leak or something out of place, 30-40% of the manufacturers estimated throw distance. So like the Olight m2r warrior is 330 meters, maybe 100-150 meters on a concrete surface are really visible.
If it’s a painted or clean surface, the distance would be over half 50-60% of the distance.
In a forest I would say 40-50% of the distance to my eyes. This holds true of Olight, Streamlight, Pelican, Maglite, Klarus, Fenix and FourSevens lights.
I can’t same the same of high cri as the tint sometimes works in your favour while other times works against you at work

I’m glad I’m not the only flashlight collector out there, I was beginning to think I was strange.
My name is Kendall and I’m a Flashaholic from western Canada

Oli
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They say you shouldn’t cry over spilled milk. You should cry over spilled beer and flashlight spill. Again you have to go back to Martin’s bunker beam shots on YouTube. Whether it’s those tunnel walls in his videos or trees, leaves,bushes, buildings, cars, the ground in front of you, any items that are being lit up by the spill of your flashlight are reducing your ability to see a Target downrange. Less spill is always better. In a lot of beam shots people find positions to get shots where there are no objects being lit up by the spill, but in the real world there will be objects in your field of view in “the spill zone” so the less spill the better. Warmer color lights also help in this regard by not reflecting as much light back at you off of those objects in The spill zone. But they also don’t reflect off of the target as much as cool white does. But I’ll happily take that trade off.

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Yeh, that’s why I cringe when I hear the phrase “useful spill” being applied to a thrower, even a C8.

Gotta love those shots taken where nearby trees off to the sides are brightly lit, but off in the distance is just black.

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Oli
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Lightbringer wrote:
Yeh, that’s why I cringe when I hear the phrase “useful spill” being applied to a thrower, even a C8.

Gotta love those shots taken where nearby trees off to the sides are brightly lit, but off in the distance is just black.

I think the technical term for that is called “fade to Black”.
dave1010
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Hmmm. Maybe LEPs and aspherics / zoomies with zero spill are more useful than I first imagined.

The Imalent MS18 has a throw of 1308m but I can imagine the glare making it difficult to see anything beyond a few hundred meters.

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The tir optics in the Acebeam L18 and L19 have a beam pattern similar to LEP lights. If you just want to see what your aiming at, the “spotlight” sort of beam is really useful once you get out past 50-60 meters.

LEP are hands down the most awesome spotlight with next to no spill. If it doesn’t have a low mode it’s not useful for that first 20 meters

I’m glad I’m not the only flashlight collector out there, I was beginning to think I was strange.
My name is Kendall and I’m a Flashaholic from western Canada

xxo
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I usually use a rule of thumb that a light’s maximum practical range is about equal to the ANSI beam distance in meters changing “Meters” to “feet”. In other words a 200 Meter ANSI beam distance would be good up to about 200 feet. If you wanted to keep everything in Meters, you would divide the ANSI number by 3.28.

Probably a better method is to use civil twilight, which is about 3.2 Lux; to get this you divide the ANSI beam distance by 3.6. Or you can just divide by 4 to make it simple for a approximation.
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3.6 is too high though. My Convoy L21B (yes B, new model about to launch for hunters to mount), with the Osram Red has an ANSI spec of 636m which can be seen 370m away on a dark green hillside, easily

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xxo
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Funtastic wrote:
3.6 is too high though. My Convoy L21B (yes B, new model about to launch for hunters to mount), with the Osram Red has an ANSI spec of 636m which can be seen 370m away on a dark green hillside, easily

How good is it for spotting a person in dark clothing at that distance?

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xxo wrote:
Funtastic wrote:
3.6 is too high though. My Convoy L21B (yes B, new model about to launch for hunters to mount), with the Osram Red has an ANSI spec of 636m which can be seen 370m away on a dark green hillside, easily

How good is it for spotting a person in dark clothing at that distance?

No idea, but spotting a black pig it’s well lit up through a scope

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Customers are spotting pigs with binoculars at 300m with the Red C8+ with my spec of 460m

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)

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Funtastic wrote:
Customers are spotting pigs with binoculars at 300m with the Red C8+ with my spec of 460m

If it’s anything like white tail deer, their eyes reflect back the light making them stand out easier. Even light spectrums the animals don’t seem to react to, reflect in their eyes.

I’m glad I’m not the only flashlight collector out there, I was beginning to think I was strange.
My name is Kendall and I’m a Flashaholic from western Canada

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Accurate brightness measurements are for comparing one light to another. Thats it.

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Oli wrote:
They say you shouldn’t cry over spilled milk. You should cry over spilled beer and flashlight spill. Again you have to go back to Martin’s bunker beam shots on YouTube. Whether it’s those tunnel walls in his videos or trees, leaves,bushes, buildings, cars, the ground in front of you, any items that are being lit up by the spill of your flashlight are reducing your ability to see a Target downrange. Less spill is always better. In a lot of beam shots people find positions to get shots where there are no objects being lit up by the spill, but in the real world there will be objects in your field of view in “the spill zone” so the less spill the better. Warmer color lights also help in this regard by not reflecting as much light back at you off of those objects in The spill zone. But they also don’t reflect off of the target as much as cool white does. But I’ll happily take that trade off.
.
.
I find what you say to be very true from my use of throwers.
My water cooled light burnt a 6500K led so I purchased a Digi-Key XHP 70.2 5700K, dedomed it, and it performed much better than the 6500K.
Guessing after dedoming it, the color was a little more than 5000K, but you could see more clearly down range. So now I will not purchase anymore 6500K leds.
.
I have tried my throwers at many places, but it is difficult to find the perfect spot to see distance and use Google Maps to get some rough numbers. There is always some interfering lights. Took them on vacation to Pensacola, Fl last yr with a spot picked at 1 mile on a yellow building with street lights beside it. You could see the light on the building faintly, but pictures would not take because of the street lights. By the numbers at 1.372,969cd and 2,343m throw or 1.45 mile, it would be short about 30%, roughly.
.
This is a very good thread, Thanks Dave 1010 for starting it ! Thumbs Up
.
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I have decent eyesight but realistically you need an optic to see any detail at night over 100m’s. I couldn’t see a pig & 200m in daylight. But these Osram convoys are making fine light weight hunting setups, if Simon tweaked a few little details he could make one heck of a hunting light for the money.

CR888

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CR888 wrote:
I have decent eyesight but realistically you need an optic to see any detail at night over 100m’s. I couldn’t see a pig & 200m in daylight. But these Osram convoys are making fine light weight hunting setups, if Simon tweaked a few little details he could make one heck of a hunting light for the money.

His new L21B is the same dimensions as the L21A, but weighing in at 210g vs 354g. This is designed mainly for mounting since the cooling fins are minimal making for short bursts on Turbo.

I asked Simon how much it would cost me to get him to design a hunting model for me. The MOQ was 1000pcs, BUT he said he’ll do it for free since he wanted another hunting model. I was so shocked because no company would normally do that. Unfortunately, the focus isn’t as good, but that only drops the range down to 1,250m vs 1,325m which is nothing. If we’re taking the ANSI range and halving it, that’s 35m less.

The center hotspot doesn’t smooth out into the corona so well because of the focus issue, but I’m not disappointed. To be able to get something this affordable which is mountable is awesome. The body is 26mm allowing it to fit into most, if not all, 1 inch (25.4mm) scope rings.

Here’s my photo

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)

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Funtastic wrote:
His new L21B is the same dimensions as the L21A, but weighing in at 210g vs 354g. This is designed mainly for mounting since the cooling fins are minimal making for short bursts on Turbo. I asked Simon how much it would cost me to get him to design a hunting model for me. The MOQ was 1000pcs, BUT he said he'll do it for free since he wanted another hunting model. I was so shocked because no company would normally do that. Unfortunately, the focus isn't as good, but that only drops the range down to 1,250m vs 1,325m which is nothing. If we're taking the ANSI range and halving it, that's 35m less. The center hotspot doesn't smooth out into the corona so well because of the focus issue, but I'm not disappointed. To be able to get something this affordable which is mountable is awesome. The body is 26mm allowing it to fit into most, if not all, 1 inch (25.4mm) scope rings.


I don't have use for it myself but that is really awesome of Simon to do!  Not a huge surprise, I guess, considering all he's done.  Are there any weapon-specific treatments like potting or stiff double springs? 
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Oli wrote:
They say you shouldn’t cry over spilled milk. You should cry over spilled beer and flashlight spill. Again you have to go back to Martin’s bunker beam shots on YouTube. Whether it’s those tunnel walls in his videos or trees, leaves,bushes, buildings, cars, the ground in front of you, any items that are being lit up by the spill of your flashlight are reducing your ability to see a Target downrange. Less spill is always better. In a lot of beam shots people find positions to get shots where there are no objects being lit up by the spill, but in the real world there will be objects in your field of view in “the spill zone” so the less spill the better. Warmer color lights also help in this regard by not reflecting as much light back at you off of those objects in The spill zone. But they also don’t reflect off of the target as much as cool white does. But I’ll happily take that trade off.

I disagree with that statement. It’s like saying a rifle is always more useful than a shotgun. Try killing a flying bird with a rifle.

Throw vs flood should be a question of preference and more specifically application.

Try using an LEP while walking in pitch dark with no moonlight. It’s like not having any light at all.

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Correllux wrote:
I don't have use for it myself but that is really awesome of Simon to do!  Not a huge surprise, I guess, considering all he's done.  Are there any weapon-specific treatments like potting or stiff double springs? 

 

I haven't needed to pot the driver for the hundreds I've sold, maybe it depends how powerful the gun is and what the recoil is like, not sure. I always install dual springs though. The 8A driver has a brass contact, so I remove it and scrape off the surface of the pcb to solder on springs. A button top battery is also required

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)

YouTube channel – https://www.youtube.com/channel/UCIUWi2vYp4CWrRkOJM70t_w/videos (Demos for my customers, and reviews)

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One thing we need to remember about this standard is that it was driven and accepted mostly by trade organizations, not us end users and enthusiasts.  That's why I've sometimes still been a little puzzled at the seemingly ridiculous parameters they settled on.  I wish I could see the full testing protocol somewhere to see if that would shed light on things.  I didn't pay close attention to when all of this was being discussed many years ago but since people and these standards organizations are not stupid, it makes me wonder if certain devices benefit from the parameters (and this would of course only be a benefit in marketing/sales).  For the average consumer, it's confusing or angering because they buy a 200m light and discover that it's only usable for half that distance...even worse with battery run times although that's gotten a little better with most manufacturers, although still not straightforward to the average consumer.  But y'know even if they were to change the standard parameters a little, clueless or unscrupulous marketers would still try to focus on the wrong things (like 50,000 hours "bulb" lifetime and eight years of run time on moonlight...). 

Change in the standard would benefit consumers, I think, while still remaining just a comparison tool for those with more than one light or an interest in the technical side of things.  What to do with that light and understanding vision, spill, "dirty" air, etc. still needs to be learned and understood by any user but that's just like basic life experience/education in other areas.  But if Joe wants to light things up reasonably well at 150 feet, Joe should have a reasonable expectation that a light that advertises 150 feet will do the job without having to understand some science or standards or do math to adjust.  Also...as long as these standards are all voluntary and the measuring equipment isn't standardized or required, much of this is still a no-man's-land in the marketplace when someone doesn't feel like playing the the same rules others do, and that never stopped even when the standards were adopted.

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Funtastic wrote:
I haven't needed to pot the driver for the hundreds I've sold, maybe it depends how powerful the gun is and what the recoil is like, not sure. I always install dual springs though. The 8A driver has a brass contact, so I remove it and scrape off the surface of the pcb to solder on springs. A button top battery is also required


Gotcha.  I thought Simon was doing that kind of thing out of the gate.  So what we have is a great form factor for the purpose but tweaking still needed.  Host looks pretty nice. 
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Any thoughts on if the ratio between ANSI throw and visible distance increases with distance?

Eg if you can see well at 100m with a 300m thrower (1:3 ratio), are things lit up just as well at 200m with a 600m thrower?

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A customer wrote a review on the Convoy L21A CULPM1 and he said that through his scope he could clearly identify a deer, antlers and all, at over 600m. The range spec I measured at 11m was 1,325m. This is why I go by the half of the ANSI rating as usable, but only on an ideal night

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dave1010 wrote:
Any thoughts on if the ratio between ANSI throw and visible distance increases with distance?

Eg if you can see well at 100m with a 300m thrower (1:3 ratio), are things lit up just as well at 200m with a 600m thrower?


What do you think could have a non-linear effect? Maybe our eyes, but is there more to consider? Particles should make a constant factor.

Smile, you cannot kill them all.

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Unheard wrote:
What do you think could have a non-linear effect? Maybe our eyes, but is there more to consider? Particles should make a constant factor.

The inverse square law, of the light reflecting back to our eyes again.

A surface lit up with 0.25 lux is like a light source itself. If you double the distance between your eyes and the illuminated surface then there should be a quarter of the light hitting your eyes.

If my physics is right then this would be the case with diffuse reflection but specular reflection (eg from a retroreflector) would be linear.

I could be totally wrong with this.

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Not really getting this. When you shine a light on an object (say a wall) 100ft away. Its the optics in the light that get the light to the wall. Isn’t it the optics in your eye that enable you to see it? This is predicated on you being able to see 100ft away. If you can only see 50 ft maximum, then you wont be able to see the light on the object, the light however will be there.

The light gets weaker and weaker the farther it travels. When it travels far enough, you can’t see it at all. This is why some stars are visible and some are not.

Isn’t this kind of what you are talking about?

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Almost. Maybe I’m completely wrong but when there is 0.25 lux on a surface then that’s the measure of photons that get reflected off that surface. So 0.25 lux on a surface is the same number of photons from a flashlight 50ft away as 100ft.

Say 0.25 lux is produced by a million photons reflecting off the surface. I have no idea how many it actually is but that makes the example easier.

So now we have a million photons coming from the light source. These spread out in a hemisphere (similar to a 180⁰ beam angle). How many photons hit a detector (like eyes) then depends on what proportion of that 180⁰ the detector covers. If our eyes are twice as close then they detect 4 times as many photons.

I’m pretty sure that’s logical and correct but if I’m the only one who thinks this then I’m probably wrong.

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