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.
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
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.
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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.
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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.
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This is a very good thread, Thanks Dave 1010 for starting it ! :+1:
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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.
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?
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
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.
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.
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
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.
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.
