Convoy S21D w/ legendary Nichia 219b :) - Review & comparison w/ Nichia 519a, E21a & other lights with Nichia LEDs incl. Emisar D4V2, Convoy S21F. (Summary & measurements on P. 1)

I have the 5700K and 5000K but can't post comparisons because I don't have enough hosts to build them in. While domed, they are visually completely neutral, not rosy at all. Same goes for all domed 519As, really. It's when you dedome that you see noticeable rosiness.

The Nichia 219c 5000K in my Wurkkos TS21 seems to define daylight neutral tint (why I think it is a must have even though I prefer warmer color), CCT 5000K & sporting Duv –0.0004 at turn on, and –0.0020 after heating up (anything in the teen or below is still very close to BBL). NOTE: I could not remove the OEM non-AR lens so this next comparison is basically various lenses placed OVER it. Not the best, but better than nothing.

For Convoy AR Green lens, I took the lens from my beloved M21E w/ GT-FC40 (the only thrower with Nichia-like tint on market). The rest are UCL lenses from App Chart / Specs. Using a tripod and raising the Opple so sensor matches the light’s hotspot, the numbers have been consistent (also helps that I seemed to spend hours doing it :person_facepalming: :slight_smile: ) . Once again the Convoy AR Green seems to be the star of the show. I will post some beamshot next to see how noticeable a 20 point Duv change is around the BBL.

1. Wurkkos OEM (equivalence of “no lens”): –0.0020
2. OEM + Convoy AR Green: *–0.0023*
3. OEM + Wurkkos Non-AR: –0.0018
4. OEM + UCL AR Blue: –0.0016
5. OEM + UCL AR Purple: *~~0.0003* (Duv change 0.0020 ~~ same as with S21D test)

Thank you so much for doing the comparisons!

I totally forgot to account for the fact that a non-coated lens actually changes duv, shifting it toward green, due to iron impurities in the glass! This implies that swapping an uncoated lens for a green AR lens actually reduces more green than just slapping a green AR lens in front of it--in your case, the difference is -0.0005 going from uncoated to green AR, and -0.0003 from nothing to green AR.

Out of curiosity: do you have a pair of AR coated eyeglasses? If so, does it seem to alter tint?

I understand your logic even though I had to go back and forth a few times. :slight_smile:

We are very much on the same track. I posted about my AR eyeglasses previously; looking for reassurance that Convoy AR Green is actually doing the right thing. I have several AR pairs accumulated over the years from different brands/manufacturers, without fail, all reflect green when placed under ceiling lights.

For anyone curious about testing your lenses and glasses: I stand under ceiling light and look straight down on the glass looking for reflection. Straight down, NOT at an angle (sometimes green becomes purple, yellow, etc. when you look at an angle). This reflection looks that way because it’s under a chandelier with 6 light bulbs.

Thank you for the reminder--I somehow completely forgot that this thread already contains your test of eyeglasses!

This is EXACTLY why green AR corrects angular tint shift!

This is interesting. I have several Convoy S2+ Hosts I’ve built, and the lenses do not show green or purple, so that means they are not AR. I have one host with Nichia SW45K emitters which I cracked the lens, oops. I ordered a replacement AR Coated lens from Simon on AE and have been using it since with no issues. After reading all this, I just checked and its the Green AR Yay! I have 2 other hosts I’m going to build with SW35k and SW27k so I’m glad I ordered extra lenses. Thank you for all the work you have put into this.

Do you think that the Green AR lenses would have any benefit on lights with Deep Red, Royal Blue or Green emitters or should I just leave the non AR lenses on those?

Green AR lens will have slightly better (probably 3%-ish if I had to guess) transmission than non-coated, but since tint is not a concern for color emitters, it's probably not worth the cost to upgrade.

You’re very welcome. This “green tint” so puzzled me once (because if I just look at the lens, there really is no green “tint”) that I made a youtube video. :partying_face: Much easier to use the ceiling light bulb reflection test. Note that a flat angle you’ll see purple; only when you look straight down on the lens that the green reflection is seen.

I just looked at my result and can’t help but have a chuckle. I appreciate your sharp mind. It’s as if you had looked at my cheat sheet; but actually it makes me feel very good and somewhat assured that my humble home test results are no BS. :partying_face:

1. UCL AR Purple: will set this at 100%
2. UCL AR Blue: 99%
3. Convoy AR Green: *98.5* (3.5 just to exactly match your “ish” lol)
4. Wurkkos Non AR 95%

When it comes to light transmission, for some odd reason the table is turned, oddly in reverse order of Duv listing. The UCL purple was horrible with Duv change but now is the star of the show (btw previously I measured about 98.4% transmission vs no lens using ceiling bounce +*HERE). I did 6 runs with the above test; hotspot on sensor this time (vs ceiling bounce), and the results surprised me with how consistent they were, considering the Wurkkos TS21 is a lousy light to test because of its numerous stepdowns.

Thank you--I'm a bit surprised myself with the guess. 95% is really good for uncoated; I've seen estimates like 92-93% thrown around on the internet. Probably depends on glass quality; some have more or less iron impurities (which manifest in green tint if you look at the lateral side of the lens). I would guess 4-5% for purple based on some random tests I've seen but can't recall, and figured that green would be a bit lower on the lumen count, reasoning below...

For the same amount of radiometric output, green contributes a lot more to the lumen count than purple, which is formed by blue and red at the tails of the luminosity function. The tails of this function exhibit very fast exponential-like decay, so the sensitivity difference between green and purple would be huge, on different orders of magnitude. Since green AR throws away green--the color contributing most to the lumen count--from the spectrum, you would expect more lumen loss.

It is a sad reality that given the same radiometric output, making tint more magenta necessarily induces a loss in lumens. (This is one reason why some emitters with higher flux bins tend to be greener, while lower flux bins have a better chance of being magenta.) Thus, when tint is concerned, a few % output loss should not really be considered as an inefficiency at all.

Beamshots of Convoy AR Green versus UCL AR Purple in the 2 lights, one with 219b 4500K and one with 219c 5000K.
Showing what a 0.0020 Duv gain does to the color of the beam.

Wurkkos OEM (“no lens”) versus Wurkkos with Convoy AR Green. A small 0.0003 Duv difference. The color difference is there, but very slight. I would not want to take a blind test to determine which is which :slight_smile: .

I am reposting a similar Convoy AR Green vs No Lens comparison, except with a LED that’s much further from the BBL line, the 219b 4500K in S21D. Again, the color difference is there. Slight maybe, but there.

For me, this comparison versus “No Lens” shows Convoy AR Green is fantastic but is not going to perform magic and turns a Cree into Nichia for example. Mainly, it doesn’t do any harm to Duv like the UCL AR Purple.

A couple months ago we had the above exchange - the question was about behavior of 8A Buck versus 12A FET, the 2 versions of Convoy S21D. Thanks to @bilakos10’s review of the FET 12A HERE, we now have an approximate answer, and it looks like stephenk hit it on the nose. :+1: :slight_smile:

The 12A FET driver indeed has a brighter max start ~2800 lm, but then stepdowns quickly and rather drastically, to 350 lm, 12% of max after just 2 minutes.

The yellow letter X superimposed on bilakos10’s 12A FET graph represent numbers from the 8A Buck version of the light. They are approximate ceiling bounce numbers, where I assumed 100% is 2000 lumens. Even though the 8A Buck is not as bright at start, it has a much more gradual and gentle stepdown. In addition, it sustains brightness much better, settling in at ~750 lm.

Looking at the above runtime graph reminds me of this puzzle, a question I always have about my Convoy: if the thermal limit is set at 55°, why do I measure 60° at the head during my runtime tests?. In fact during my runtime comparisons, the Convoy always measures the hottest among the lights I have. Most lights stays at 40-50° at the head, versus 60°.

Here is my attempt at explaining this discrepancy. Essentially it is true what Simon says, there is a thermal limit of 55° and it does trigger stepdown. However the stepdown is limited to a power level that is preset at factory. This level is fixed, regardless of what the temperature is. This would explain why my Anduril lights are all over the place with brightness output, and my Convoy is a flatline with hardly any up or down regulation.

Not complaining at all. The flat output is one reason why I love my Convoy’s. Anyway, I am not sure if my “theory” is correct at all. Please take the “explanation” with a table-size grain of salt and correct me as needed.

Flashlight porn to spice up this somewhat dry topic. I have dual citizenship lol so you’ll have to put up with my love for Emisar D4V2. They are like little jewels that fit perfect, PERFECT, in the hands. Enjoy your Convoy but do get an Emisar one of these days to know what the hype is about :innocent: .

My question would be which light will be able to sustain a higher output on identical leds, the S12D with the 8A buck driver or a D4K/D4 with the 8A boost driver.

Might be close but with similar calibration I think the S21D would have the edge due to the more basic temp regulation algorithm.

Interesting discussion. I made some comparison of S21D versus D4V2 previously, but only with the NON-boost driver version of my D4V2.

I am not sure if the sustained brightness is related to the driver, or more to the stepdown algorithm that Convoy uses (basically a fixed lower limit that a Convoy light will not go lower, regardles of temp)? In other words, if D4V2 with boost driver has the same thermal regulation algorithm as the non-Boost, wouldn’t it step down just as much?

Looking at S21D FET vs S21D Buck above, I wonder the same thing. Is the drastic runtime difference due to difference in driver, or difference in thermal regulation algorithm? I didn’t think flashlight could be so complicated and interesting. :slight_smile:

Which exact driver (boost 8A?) is in the D4V2?

Right, back to the green vs purple AR glass. This is my testing with Convoy S21Es on 40% mode, hotspot measurement. Opple Lightmaster 3 Pro.
2700k green AR 2681k 97.9Ra +0.0010 DUV
5700k green AR 5147k 98.1Ra –0.0013 DUV
5700k purple AR 5157k 98.3Ra +0.0018 DUV

The lens switch is between 2 & 3 right? If so, that’s about a 30 point raise in the Duv? We are getting results that are very close. Mine has been about a 20 point raise from green to purple (not purple to green lol - I’m confused, and can be confusing).

Sorry for the confusion. My D4V2’s are all regular, NON-boost version. AFAIK this means CC 9A for the 219b D4V2, and CC 5A for the E21a D4V2.