[PART 1] Official BLF GT Group Buy thread. Group buy officially closed! Lights shipping.

Enderman, that is a nice idea but for the fact that an LED requires a parabola to have efficient output. Many years of research and development has proven the second design to be more effective with a flat surface LED emitter than the shallow bowl that works with an element style bulb. The difference is in output transmissive angle, the shallow bowl style would give a horrendous beam with an LED source.

I once researched the design for LED’s and one of the main theories was of a square parabolic design, square meaning equal dimensions diameter to height. There have been a lot of variations on that, to some degree, but it’s been the most successful to stay close to square such that a 120mm reflector should have a fairly close to same depth of 120mm. The TN42 “reflects” this, with a very deep wide reflector that shines a proven mile. (The TN42 is actually something like 90-92mm reflector diameter and in the 75-80mm depth area, this is as measured without disassembling)

Thinner fins also means less airflow, there is no fan here so convection has to do all the work.
Maybe someone can look for a peer reviewed research paper on fin density to find the optimal thickness for heat dissipation?

Theories are fine, real world provenance rules. I give you, as evidence, the Olight SR90 Intimidator.

Please note that I DID say “not to an extreme”. Thick bulky fins do not induce induction in my own experience when pushing an LED to it’s limits.

Ok? It’s not a theory that if you leave less space between fins that air has more difficulty moving…this is elementary school knowledge.

I’m just saying that you can find an optimal point where you have more surface area but still good airflow and that is the point with the most heat dissipation.
Cramming as many fins as possible into one spot doesn’t automatically mean it is better.
I think it’s pretty obvious that a solid block of metal (aka infinite fins stacked together) has worse heat dissipation than with fins with good space in between.

btw, the SR90 is only 30W of heat.

I’ve not been too active lately, and we have… a new BLF project!

Nice, put me down for one (with zero spill please :smiley: )

Enderman, this thread discusses the relationship between throw and reflector size. Understanding the concepts in that thread really make it much simpler to think about flashlights and throw.

I do not think Dale is talking about CPU cooler style thin fins, just thinner then they are now.

There will be some revisions to the cosmetic design before finial production for sure but it is not something worth worrying about until we at least find a reflector as that will set the final shape we need to work around.

Feel free to give input, we will keep it in mind going forward, just don’t expect much to happen till we find a manufacture. That is the singular goal at this point before anything else major can happen. For that we need to have some nice specs and a great sales pitch ready.

Maybe YOUR SR90 is only 30W… :stuck_out_tongue:

I agree though, optimization is critical. Which is why I suggested the fins not be taken to an extreme. Thick grooved fins that appear as blocky though are more a “look” to imply rugged, not actually all that useful. I like to use a fin that is the same width as depth, giving equal surface area up the sides, across, and back down. A doubling of the depth might look good but I’m not sure it actually improves anything functionally.

Air won’t be stagnant in the fins, given a disparity the heat will rise and pull cooler air in between the fins. Ambient temperature will be tantamount to determining effectiveness, we have nights here that it can be in excess of 100ºF at midnight, this is not conducive to a hot-rod staying cool. Likewise, on a 40ºF evening with a drizzly mist in the air, none of my hot rods will get hot enough to warm my hands. Point being that the style of the fins will not always be efficient in every environment. There will be a LOT of mass here though, so the fins may not have a lot to do with the light staying cool. I already have lights with the XHP-35 pushed to the limits, it’s a given point, a larger light can’t push it any harder, all it will do is give more mass to aid in dispersion of the produced heat, effectively cooling by sheer size.

(my SR90 is over 85 watts. I can also tell you with no uncertainty that the fins on a Noctigon Meteor DO NOT help with 133W.)

I do know how reflectors and optics work.
A larger proportion of reflector to die area will result in less beam divergence and longer throw.
I still highly doubt adding 2cm diameter will magically create an increase of 200k lux.
Your point is…?

Throw (cd) is proportional to the reflector area, which it seemed like you did not believe. Very approximately, if the TN42 makes 700Kcd with 100mm diameter, (120/100)^2=1.44x more area and beam intensity. So roughly 1.44x700=1008Kcd.

Reflector area is a three dimensional paraboloid.
I don’t know if you’re trying to say that the surface area matters, or if you’re trying to say that the diameter/base matters.

If we assume the TN42 has a 60mm deep reflector (i’m not sure about actual depth), the area is 13181mm^2
If the GT has the same proportioned reflector, it would be 23433mm^2 almost 1.8x the surface area, and I can guarantee you that it will not give you 1.8 times throw.

If you’re talking about the area of the base, I can immediately prove you’re wrong:

Look, same diameter or base area, but the first one only collects like 10% of the light coming from the LED since it is so shallow.

By your logic, these two should throw the same because they have the same diameter right?
I think it’s pretty obvious that these reflectors will throw differently.

Well, with all that precise math lets be accurate and say the TN42 makes 702.5Kcd. :smiley:

1.44x702.5= 1011.6Kcd? SuhWeeeet!

I too am skeptical about 1Mcd from a 120cm 120mm reflector.

It’s exponentially more difficult to push the light downrange, I’m gonna act like I’m from Missouri on this and y’all are gonna need to show me. :wink: (meaning I gotta see this!)

Edited for size. :wink:

Me too, I think setting expectations that high will lead to disappointment and complaints about initial false advertising.

Although Vinh was able to get 900kcd out of a heavily modded TM36 with XP-G2 at 5+ amps, so it’s definitely not impossible to reach 1Mcd with a reflector.

The thing is, it’s super difficult to pull off. Vinh cherry picks emitters, goes through perhaps dozens to find the one he wants to make that kind of output. It’s almost a fluke when he hits it, because it’s so difficult to do. You simply can’t mass produce that, it’s a full onslaught of custom work to tweak a light that hard.

I had my SR90 doing right at a mile at one point, wasn’t easy. When I saw the email from Thrunite on the pre-order of the TN42 I pounced (my light is Serial # 00002), never believed a factory mass produced light would make a mile throw. So the undertaking here is pretty enormous, and yes, it’ll be epic if successful and the company that builds it for us will have hit a very big milestone.

As a photographer, I fully understand the issues at hand to push light further out. It’s just not as easy as doing a little math. We’re at the ceiling of the LED’s, the final tweaking is going to be about smaller gains, baby steps, and I’m just not sure going bigger, not this little bit bigger, is going to make such a huge difference. 200mm maybe? I don’t know, which was my early question here, just what is the actual limitation of pushing the light downrange?

FWIW, 702.5Kcd equates to 1.04 miles. 1Mcd equates to 1.24 miles. While the “Million Candela” sounds truly incredible, it’s not really so much further. Two tenths of a mile, will you even be able to actually see the difference? It’ll be difficult, even with a scope…

Make no mistake, I’m not saying it won’t be impressive, because it sure as he will!

And I guess y’all already know that I have a photograph of a sheet of paper illuminated at a measured one mile from the TN42, it really does do it!

Dispersion at distance is the enemy of course. That super tight hot spot at 100M disappears way out there, so of course the tighter we can keep it, the further it’ll reach.

My wife missed focus in the picture of the spec sheet. In the big picture, my wife can be seen to the left of this sheet of paper wearing a pink top and black pants. To be able to see her black pants from a mile away in the picture, as illuminated by the flashlight, that’s just mind boggling! And we are undertaking BESTING this performance! Yeah, it’s exciting, dam* straight it is!

Sounds like it going to be a great light!!!

Yeah, that’s definitely true. Vinh only made 5 of those TM36vn lights.
The way you increase throw is by having more lumens, smaller LED, or larger reflector, or any combination of the three.

  1. By increasing the lumens without changing anything else you basically make the same spot, just brighter, which directly translates to more lux. An example of this is running an LED at 4 vs 5 amps, 5 amps will have higher lux.

2) A smaller LED means that the rays coming from one side of the LED vs the other side of the LED form a smaller angle when hitting the reflector. Smaller incident angle = smaller reflected angle, which means the light rays are travelling more “parallel” or “collimated” when exiting the flashlight. Less beam diversion = farther throw but smaller hotspot at a far distance. Same lumens, smaller area, results in higher lux.

3) A larger reflector (with the correct proportions) should have the same effect as using a smaller LED. With a larger reflector, the focal point (where the LED is) will be farther away. This also results in a smaller incident angle, and smaller reflected angle, and less beam diversion.

4) some other small stuff like smoothness+precision of the reflector, light % transmittance of front glass, centering of LED, and tint of LED can also make the light brighter.

What I think people are having trouble understanding is that the diameter of a reflector is not the only thing that matters of a parabola.

It is the apparent area, so the area that you see when you are far from the light and looking into the front. As explained in the linked thread.

Reflectors with the same diameter but different depths will have slightly different frontal area. See here for discussion: Reflector width vs depth for throw?

In your example of the two different shaped reflectors, they would have similar throw. You are right the shallow one would collect less light and so there would be fewer lumens in the beam, but the peak intensity would be similar.

So when we reach the maximums, ie: most lumens, smallest emitter, largest reflector, then it comes down to fine tuning. Better AR coating, better reflector finishing, best possible emitter placement, maintaining the coolest emitter to keep output high, it becomes crucial to keep the small details in maximum optimization. Which is what this journey is all about really. Taking that one last parameter, the size of the reflector, to the next level…

And of course keeping the price real. :wink:

We could just tell TexasLumens what we want and he could lay it out on his CNC machine and make it happen, if we told him price was no limit. :wink: