lumen aeternum
Enlightened
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distance & max lumens are the only specs always available. What can I do to compare two lights and pick the one with the least light in the corona?
Can I use ANSI distance / max lumen to guess at corona brightness?
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richbuff
Flashlight Enthusiast
Differences in reflector configuration between the two lights?
There is simply no good way without knowing more about the emitter (led) and reflector dimensions.
Generally speaking, a larger led die size, and a shallower reflector will create a wider hotspot, corona, and spill.
And a smaller die emitter, a dedomed/HI led and deeper reflector will produce a tighter beam all around.
But there are so many variables and crossover points that my simple explanation is "in theory" only.
And as my favorite Poli Sci professor once said... "A great theory that's only great in theory is not a great theory."
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Timothybil
Flashlight Enthusiast
Would there be any relationship between the amount of lumens and the candela measurement. I mean, there are only so many lumens being put out. If one candela number was significantly larger than the other, wouldn't it stand to reason that the cause would be that more of those lumens were being concentrated in the hot spot, and therefore weren't available to add to the spill? I admit that differences in reflector size and depth will affect the size of the hot spot, but still the more candelas in the hot spot the fewer available for the spill.
I have no basis for this except my knowledge of parabolic reflectors and what I have picked up here about the measurement of candelas as opposed to lumens.
I have no basis for this except my knowledge of parabolic reflectors and what I have picked up here about the measurement of candelas as opposed to lumens.
Kinda, theoretically. If you knew how big the hotspot was and how consistent it was, then you could get a feel for how much of the output was there. But as candela measurement is on the hottest spot in the hotspot only, we really never get the rest of the information.
The hotspot's most intense spot could be 500kCd, with an inch away in the hotspot at the target being 200 kcd. Or maybe that inch away will register 450 kcd. And how wide is that 200 or 450kcd pattern against the target?
Will the hotter area of the corona be 100 kcd or 50kcd? And how wide is that corona?
Point is the cd only tells you the absolute peak point, it doesn't give you and area/width numbers to go along with it, so you can't identify how much is going into that relative to the rest of the hotspot/corona/spill.
If you had a complete beam intensity mapping, like a heat chart of the beam pattern, and a math/physics skillset, I think you could back into more specifics. But that's not really practical.
Real example.... my T6vn has about 5100 lumens and 400000cd. Can you tell me the proportion of light that is in the spill vs the corona by these numbers? Or how wide the hotspot is? Those numbers don't give those answers.
Hope this helps explain. There are better links online than my own explanation here...
Edit: reading post 1 again... OP, what you're looking for is a "pencil beam thrower". Olight m3xs-ut, Thrunite Catapult v5, Skylumen T21vn, something like that. While pencil beam isn't a manufacturer category, that's what we all brand them here so those are the words to look for. They will have intense hotspots with little in the spill or corona.
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Chicken Drumstick
Flashlight Enthusiast
To me the Olight M3XS-UT is not really a pencil beam. Yes it has a tightly focused and high intensity hotspot, but it's also fairly large still and has a bright large spill beam. It just isn't anywhere near as intense as the hotspot.
A 'pencil' beam for me would need much less evident spill beam. Old XR-E emitters could sort of achieve this in a large reflector, as the hotspot was narrow and very intense and the low lumen output meant the spill beam was much less bright than on modern lumen monsters.
Apart from that you'd probably be looking at a TIR or aspheric optic or similar.
A 'pencil' beam for me would need much less evident spill beam. Old XR-E emitters could sort of achieve this in a large reflector, as the hotspot was narrow and very intense and the low lumen output meant the spill beam was much less bright than on modern lumen monsters.
Apart from that you'd probably be looking at a TIR or aspheric optic or similar.
X2 on the candela numbers. Good explaining TB. At least that's how I gauge things.
I have a 100 lumen light with a higher cd value than it's 178 lumen counterpart. When I wanted a light to shine into small tunnels I picked the 100 lumen version. When I wanted one to guide my steps in the woods I picked the other one. Both throw about the same in my eyes but the higher cd version has less spill so it preserves my side night adapted nearby vision better and in humid conditions, fog or smoke it will not light up nearby molecules, thus making it appear to drill a hole through said smoke, humidity or fog better.
I have a 100 lumen light with a higher cd value than it's 178 lumen counterpart. When I wanted a light to shine into small tunnels I picked the 100 lumen version. When I wanted one to guide my steps in the woods I picked the other one. Both throw about the same in my eyes but the higher cd version has less spill so it preserves my side night adapted nearby vision better and in humid conditions, fog or smoke it will not light up nearby molecules, thus making it appear to drill a hole through said smoke, humidity or fog better.
