Tom, I’m finding that the donut hole is specific to each reflector and the amount of throw it’s capable of producing. Maximizing throw tends to take the focus further out, leaving the donut hole considerably further out…or at least in a massive reflector like the TK61 or SR90. That’s one of the things I was having trouble with on the focus with the TK61, getting the beam convergence as far out as possible so it wasn’t crossing over and enlarging out at distance.
The reflector in my Courui gives a tubular looking beam, doesn’t seem to have that convergence at all.
If you have some space where you can shine the beam out to inifinity look at the beam from the light out, you should see a darker “V” in the middle out to 3’ or a bit further on the big throwers. That should be about the distance the donut hole disappears. Unless I’m missing something completely, and that could very well be…and not for the first time.
That “v” is quite evident in this picture, with the TK61 shining across the Mississippi River…
A massive carnival searchlight, notice the men standing beside it…. this is the kind of “into infinity” I was talking about. Check out how far the “v” goes out in the center of this huge beam!
The opposite of using a magnifying glass to burn a bug. There’s a fine point that the light is in convergence, then it spreads back out on the other side of that point.
You can see where the effect comes from with a piece of paper laid over the front...
Roche F6 XML2 10* TIR:
Roche F6 XPG2 stock OP reflector:
XinTD C8 XML2:
edit: The XinTD probably needs the LED moved farther up, you can see it's not using very much of the reflector. It's got a standard ~.035" thick centering ring, where the pre-built XinTDs use the much thinner adhesive insulator.
I’ve been looking at the formula for figuring the parabolic curve, and it would seem that this “v” shape we’re seeing is due to an imperfect parabola. This is probably also due to the fact that an LED does not have a point light source so the reflector is having to gather light from a broader source and collimate it into the cone we desire. Effectively though, the differences we’re seeing are probably the result of the success rate of different manufacturers at getting the curve right.
Dunno, I'm having a tough time seeing the V - I see convergence, I don't see divergence on the other side. I know with lights like the Shocker and HD2010, The kcd #'s would go up as that donut's distance got less. Maybe you are right about the big reflectors. I recalll rdrfronty testing lux at many distances and saw no difference from 15 m on out, but that could be the specific lights he was testing at the time. I don't think I've seen any one else test lux (kcd) at significant distances - takes 2 people of course and dark open space.
On my TK61, I got the head loose and dial in the focus simply by turning the head on or off. Doing this while aiming it at the meter gave me the top result, and that has the donut hole hitting at about 6’.
For testing at 15M, I put the meter on a tripod and the video camera on another, zoom in with the camera and watch the meter on it’s screen.
Distance here is a non-issue. I have plenty of that. My driveway is 267 yds long.
Interesting bout the TK61 - never saw that sort of effect before, but pretty much all my measured tests were at 4-5 meters. The biggest lights I tested were the TN31's and K40.
comfy - those beam pics are nice! I think I sort of understand it - looking at the concentration. The XinTD C8 though looks a lot like the S1100, as far as where the brightest part of the beam is, closely around the center spot?
Well, I won't have much of anything to add to the mod thread. My mod will end up being mostly cosmetic. I will be sticking with the stock led/star and the stock driver. I replaced two of the three resistors, for more output, but that's all except for heavier wire and resistance mods to the springs. I also did add copper under the star and I shaved down the locating ring for the led, till it's paper thin. That's about it, but since my mulitmeter is acting bad and so is my lux meter, I won't be doing any testing of anything other than seeing if it turns on and changes modes.
Copper Heat Sink
Finished?? Nope, I ruined the battery holder, so I will have to go buy one. Either that or give it away with no holder and let someone else get one. I still don't see why it fried, but it did.
Anyhow, I did get a measurement of 104,500 lux at one meter out of it using 4 18650 in series, with heavy wires, on the bench and it never dropped from there, for the two minutes I was checking.
That's all I can do. I have a couple meters coming and I will rig one up for amps, with some 12ga wire and see what I get for amps. I replaced two of the R120 resistors with one R075 and one R100.
Yes, I read your posts. I figured somewhere around 6 amps, but without a meter, it's guessing only. The holder fried when I put the batteries in it, with no load on it. It got hot in my hand and started smoking. The batteries weren't even the least bit warm when I pulled them out. I checked them and none had dropped any voltage to speak of. I have no clue. I imagine it was me, but I don't know what. I didn't do anything except disassemble and reassemble, but that was enough. One edge of the holder right over one battery was where it fried. It burned up one of the components and that chip melted off the board and melted the solder off the spring there.. Didn't take only a second to do it. Looks like the outer ring touched somehow, but alignment is correct.
Maybe we should have a new list in OP. Who can fry or damage their battery holder the quickest?
Old-Lumens is in the lead with a second...
Ideally I need a minute and low voltage cells in order to do some damage. My light is still working fine with high voltage cells though. I think that puts me in 2nd place at the moment. :D
Seems like the integrated battery charger carriers are doing more harm than good. Hard core flashlight enthusiasts know better to charge batteries in their lights and the circuitry in the carriers are going poof.
I’m considering only dedoming my K50 LED and call it good. Messing with the resistors seems risky and doesn’t give a lot of gain in actual throw. Vinh’s best result with K50 is 550kcd (1483m) and your result of simply dedoming the LED gives 420kcd (1296m). There is “only” a difference of 187 meters and I don’t want to take the risk for that.
Did you re-position the LED or reflector after you have dedomed it? Or simply put them back to exactly where they were?
bibihang, all I did was remove the head (not as simple as it sounds) so I could get easier access to the emitter, then de-domed it hot right in the light. Put it back together and am very pleased with it. One could forego the laborious process of removing the head and do the cut on the dome down inside the head, not easy but certainly do-able. Then it would be only a matter of a few minutes and you’d have it de-domed and throwing this nice tight beam.
, so I will have to go buy one. Either that or give it away with no holder and let someone else get one. I still don't see why it fried, but it did. 