That’s really a big head for a single emitter light like this!
So no surprise that it throws better than the K70 although with lower lumens output.
Yes, but I wasn’t talking about the distance. I meant that if you dim a light to half its lumen output, its beam intensity (in cd) will also be half.
Boost or Buck is irrelevant if the output is constant current and the drive circuity is competently designed. As long as the inductor is sized to switch enough current without going into saturation after the battery voltage sags, you’re pretty much set.
IMO, none of these lights should use cells in series if they need unprotected cells. Unprotected cells and series use is a dangerous recipe without a proper battery monitoring system. Of course all of these lights all lack such a system.
I dunno, I just see it empirically (measured) more often than not. Are you sure that's what you measured in lumens vs kcd for a thrower?
Actually it's probably wayyy more complicated than what I said. All sorts of variables - our meters (cheap ones, like under $1000) I believe are calibrated better with CW tints than NW tints, so they tend to read NW's lower and probably in the high range of CW read higher on the meters. There's other factors. Just checked some of my numbers, and sometimes yes, kcd scales well with lumens, but other times I've gotten higher differences on kcd than lumens, percent wise, and I thought as much as 2X.
This is all part of the issues comparing two lights with different tints. Specs from the manufacturers that offer multiple tints are typically not providing the data points per tint, some do, most don't. Chances are they'll quote CW because of the better results.
I can see that stereodude, which would make the Thrunite safer than the Acebeam on the sheer fact that it’s 2 cells in series instead of 4. You can put 2 cells in the carrier and run it, or use a second pair in series for extended run time. Can’t do that with the Acebeam.
I should try other cells and see if I get a noticeable or measureable difference in output, that should tell something about the circuitry, yes?
I can measure a lower mode and extrapolate, but if you have half the lumens then no, you wouldn’t have half the candela. It’s that exponential issue again.
I’ll measure and see what shakes loose.
But, in photography terms… I’m standing on the sidelines at a football game, the punter is directly in front of me in the middle of the field… he’s 25 yards away. Easy flash shot. He punts 50 yds downfield to the sideline I’m standing on, I want to capture the opponent catching the punt, he’s exactly 50 yds from my position. Twice as far away. It’s going to take 4 times the amount of light to reach him for that shot. 4 times at twice the distance.
Candela is a measure of intensity in the center of the beam, so if you cut output in half…. I’ll measure it.
Ok, today for sure this is not my cup of tea. So I’m gonna just tell you guys a few test results and I’m sure some one of you can figure the percentages easily enough…
The TN42, on level 3 of 4 (High) makes 1003.95 lumens and 46750 Candela
The TN42, on level 4 of 4 (Turbo) makes 2459.85 lumens and 702500 Candela
So what does this tell us?
(I have to say here, I’ve tested the candela on this light at least 4 separate times, with the cells at different charge levels two of those times and fresh or almost fresh the other two… every stinking time the meter tells me 2810 with a x100 setting. 28100 at 5M, for 702.5Kcd. Reliable, the most reliable I’ve seen to date)
Everything else being constant doubling the lumens doubles the lux/candela.
Maukka, did you see my test results directly above your post? That doubling concept is obviously not true. I’m pretty sure that double 46.75 isn’t anywhere close to 702.5, even with the differential there.
Dale, I can’t explain your result, but in Maiden666’s review the measured Kcd scales very well with measured lumens and this is generally what I have observed with my lights.
Testing the light’s output with cells at various states of charge would give you how good the circuitry is. Like fully charged, 75, 50, 25%. If they’re all the same the circuitry is very good at running constant current through the LED even as the cell voltage drops and the current draw from the batteries increases.
Think of it this way:
If the intensity of the hotspot doubles when changing modes, the intensity in every part of the beam has to double too since the reflector and emitter are the same. Thus the total output doubles = the lumens double.
Led-Rise’s calculator is misleading. You cannot directly convert lumens to lux. Lumens is a measure of total output, lux is the measure of intensity in the center of the hot spot. A floody 1500 lumen light creates very little lux, whereas a pencil beam thrower making 1500 lumens puts virtually all it’s lumens down the middle, into the hot spot, for far greater Lux.
A simple converter just can’t show that.
Theory versus provenance. The numbers I just got from my meter are truth, without conjecture.
42% of the lumens is making less than 7% of the candela. That’s a simple fact. All the theories in the world can’t disprove it.
Candela, downrange illuminance, isn’t all about the emitter and driver and reflector. It’s about the avaialable light spreading out in a cone as it travels downrange, very quickly losing it’s power.
Science is wonderful when in the lab or sitting at the desk, going out in the field and proving the science is an entirely different matter.
Y’all might be the scientists, I’m the guy out in the field taking pictures of real world results. And the results don’t agree with the science.
Build a light, measure it’s lumens and candela. Then de-dome it. Measure lumens and lux again. You’d find that that the lumens dropped while the candela nearly doubled. Less lumens, more candela. Fact. There are more variables at play here than it would seem.
I’ve done this literally hundreds of times.
Modifying the emitter is not keeping everything else constant.
But, taking a lumens reading immediately after taking a lux reading on the same light, same cells, IS maintaining constants. And those number disagree with the representation of physics here.
I can’t argue with physics, unless the chapter and verse being quoted are wrong. 
By the way, who said we couldn’t send a man to the moon? And who is now planning to send men to Mars? Physics and it’s laws change as we learn, there are very few hard cold facts.
I’m not trying to convince anyone of anything. I’m the guy with the light in hand, the results from testing in front of me. It’s everyone else that’s scrambling trying to figure it all out. Fact is, at 42% of the output, the light is making less than 7% of the throw.
That does not support the theory that halving lumens also halves candela. So when the facts from testing don’t support the theory, it’s time to put new chalk on the board.
Could you humor us and take the measurement again? On turbo there was 28100 lux at 5m. How many lux on high?
The meter read 1830 on High, 28100 on Turbo. My meter has 3 places, it actually showed 183 to the power of 10 in High, errored in Turbo and I had to switch to the power of 100, where it showed 281.
I argue to understand, not necessarily to prove anyone wrong. I forget a lot. Widely known fact. So if I can argue myself to an understandable truth it is well worth all the verbage expended in the acquirement.
Yes, it is entirely possible that I made a mistake taking the readings, so I will do it again. (I have been known to make the same mistake over and over, so bear with me. 
) I will go slower, double checking mode levels along the way, for extra care and authenticity.