Looking at the charts I’m surprised the output loss is so severe. According to TA tests, E21A CRI9080 at 2.5A has the same output as XM-L2 U2 (912/910 lm). At 1A XM-L2 is 7% better.
Skilhunt uses U4 bin and you used D220 which is a little lower.
This would make me expect ~18% lower output at peak and ~23% lower at 1A. I’m not sure what’s the current at the steady state but it must be quite close to 1A.
At peak I see ~22% lower output which is can be accounted for by test variation.
But at the steady state the difference is ~43% and that’s definitely too high.
IMO, TA measurement is too optimistic. Brightest E21A is D320 at R70 = 320lm at 700mA (Tj=25C). It’s comparable to XML2 U4, 320lm at 700mA (Tj=25C). Skilhunt use U4 bin for the CW version, mine is NW version. And I pretty sure it’s U2 bin. I measured H04RC using D220 E21A R9080 which means 220lm at 700mA (Tj=25C). Thus, 4x (4P) E21A D220 at 700mA produce only 245,4 lm - still much lower than a single XML2 U4.
I can’t explain the big difference in output either, my measurement device is not as sophisticated as Maukka’s. Let’s wait for his result.
My “unofficial” test showed ~80% - 81% TIR lens efficiency for quadtrix E21A. Pretty normal for uncoated 16mm TIR optic. Quadtrix E17A should be somewhere around 84%
All these numbers are kind of confusing to me. Are they right or wrong? Are we waiting on some more results to come through?
I kind of just want a high CRI headlamp that can output like 400-500 lumens indefinitely (not throttling down because of heat) and I can keep swapping batteries into as they run out. Is this what I’m after?
I’m really glad that maukka started selling his calibration lights and that so many of us have them. Before that those were available, people with real numbers would hesitate publishing them because they were a lot lower than the rest (I have noticed easily a variation of 30-40% among calibrations of different people), and the temptation was there to match your calibration to what was generally accepted (many flashlight manufacturrers did that too). My led tests always gave low-ish output numbers compared to “the rest” (BLF members and flashlight manufacturers), until maukka’s calibrated test rig showed that they were actually 7-11% high (depending on spectrum, my imperfect sphere coating generates limited but measurable spectrum errors).
But even apart from calibration differences, that since maukka’s lights are for sale have decimated, the fact that most people (including TA) use cheap luxmeters with very imprecise optical filters, is still a souce of error that can cause a variation that for some tints can be as high as 20% (see my luxmeter tests).
Indeed, TA sphere pre-callibrated was a big step forward but the luxmeter is still holding it back.
Now that there’s Unit-T UT-383S this may be possible to significantly improve (but not solve) with reasonable cost increase…
Though one thing that worries me in this meter (aside from being untested) is its absence from Uni-Trend website.
I do not see how this luxmeter would change things, it is yet another cheap luxmeter that for sure will have optical filter errors. A good luxmeter filter that precisely corrects the sensor for the Vlambda curve is still very expensive (as in hundreds of dollars for the filter alone), and none of my tests sofar have proven otherwise. So there is no way around that, and errors of 10% upwards will remain. I have not tested this specific luxmeter but I have no illusions.
In your tests UT383 did way better than other cheap meters. If UT383S performs as well, it’s probably significantly better in the cool region HS1010A that TA uses.
If you look into the table I made of how the different meters measured a number of different flashlights, you will see that while it performs better than some others, the U383 depending on light source, measured from 5% too low to 15% too low so a 10% variation on top of the calibration error, which does not make it a great luxmeter, just better than the worst ones. That is quite a range of error to consider. There seems to be a performance in between, the one Extech meter that I tested differed only a few percent from the reference luxmeter, which also shows in the wavelength response.
Unfortunately no, this is not for you. This H04RC steps down in 2 minutes to ~50% max output. Less than 400lm continuous with R9080. You better look for bigger light, not a headlamp.
But TA calibrates with reference lights which should cancel this error.
And I think $370 for Extech is way too high for an average enthusiast. At least I keep it out of my scope.