Both are 8A Buck
Yes, according to Simon, but has this actually been confirmed (with pictures of the driver)?
Iâm curious how a dual-channel buck topology looks like.
It didnât arrive today, so no delivery until at least early next week 
Beamshots on the âwall of truth,â my living room, with white balance of DSLR fixed at 5000k. This is white wall hunting at its best, for me more revealing than the close up shot above. (Next would be real scene of plants and rocks in my front yard. But not yet because Iâd like to give my neighbor a break from this craziness.)
I hope you could see the very subtle rosy tint of S21F vs S21D 519a, which is very slightly more yellow. A reflection of the 40 point change in Duv.
Is it worth it? How nutty do you want to be with this hobby? If you are reading this thread, IMHO the answer is a resounding yes, maybe.
. yes, I do see that subtle difference. It is so subtle that I would not buy S21F just to get a rosier 519a.
I would, however, consider dedoming a 519a at 5700K if that were my goal.
But group modes are quite different.
Yeah they are. I slightly prefer the 12 group mode on the S21D, I wish it was the same on the S21F. Iâm not a fan of the ramp mode so I use the stepless mode.
Or 219b 4500k, or 519a 5000k, etc. (it doesnât have to be a de-domed LED). If you are starting a collection or this is first Convoy Nichia light, then I agreed, this may not be the best choice; the S21D is, IMHO. And just to be devilâs advocate for the tint-ramping crowd and pointing out the obvious, a de-domed 519a 5700k doesnât have tint ramping.
OTOH, for people with multiple Convoy lights already, and the 30 or so lucky people who got it, I wouldnât advocate selling it either. Itâs Convoyâs first tint ramping light, itâs only 30 bucks with a buck driver (!), and it has a beautiful tint, so far (I havenât tested the other CCTâs).
Simon curiously said something to the effect that he doesnât have enough 519a 5700k LED (?? pls correct me as needed), so who knows when itâs going to show up again. âCuriouslyâ because I thought he would buy LED in the thousands.
Hmm interestingâŚeven Hank doesnât have 5700k listed as an LED optionâŚ.maybe people are running low on stock
I was debating on de-doming the 2700k LEDs in the S21F for a more broad range of the spectrum but was afraid the mixture of domes will have a tint shift. If Simon canât produce more for a while, maybe Iâll hold off lol
Wondering why you like stepped modeâŚ.whatâs the thinking? On the most popular group #2, the final step goes from 35% to 100%âŚ.I donât get that idea.
I think if the 21D had ramped mode I already wouldâve bought itâŚpart of the reason I was waiting to see the 21F.
.
Iâm not a fan of the switch feel for brightness ramping and the ramp speed isnât consistent for me. I like it more on Hank lights and with anduril.
Also, I usually like to start my lights off from low to high. With the S21F, the brightness in moonlight mode cannot be adjusted or memorized. If the S21F has the ability to turn off memory mode like the S21D, I wouldnât mind using brightness-ramp. It seems weird to go from 40% to 100% but in person, it doesnât get that much brighter for me lol
A trick I like to do with the S21F is while leaving it on moonlight mode, I un-twist the battery cap to reset the stepless mode back to lowest mode.
We donât perceive light/brightness in a linear way - some eyes are slightly more sensitive than others but generally it takes a lot of extra lumens to perceive a lot of extra light. For most people 3-4 times increase in lumens will look about twice as brightâŚish. Remember that Simon is listing current (amps), not lumens, in these percentages, and that emitters are also not linear in their input vs. output, so that compounds it a little more. When those modes were settled upon years ago, the idea was having good visual differences in the light output, so usually youâre going to see at least double between modes, sometimes triple. This will look different to your eye when the beam is outdoors where you can shine at something in the distanceâŚindoors on a nearby wall or whatever, it may not look like as much of a difference.
This is a shortcoming/flaw of the driver and firmware programming. Again with the non-linear thing here. The ramping is made of many many little steps, spaced much more closely together than the few that are in the stepped mode option. If the many little steps are linear/evenly spaced, then we get this weird fast-slow ramping effect. When TK worked on Anduril she figured out that an algorithmic approach for the step spacing rather than a linear approach was best for getting a nice visually-smooth ramping action. This has been brought to Simonâs attention but I donât know if or when he might get his driver engineer to improve it. He may not think itâs worth the effort, or maybe he wants to sell through stock first, or who knows. With any luck he might actually adopt Anduril after all but that remains to be seen.
Apologies if Iâve missed this in this thread, but how does the channel mixing/current distribution work on the S21F?
At 2700k or 5700k, 100% mode, does the light put all 8A into 2 emitters, or can each CCT LED pair only get 4A max?
Now beamshot of actual nature scene; for me the ultimate judge. Hope you could see the very subtle green of S21Dâs 519a 4500k (measured 4000k) in comparison. And the pink tint of S21F 519a tint shifter @3700k.
If youâre new to this, please keep in mind 519a 4500k is an outstanding LED that makes most other non-Nichia LEDâs look green. So this subtle difference is actually IMHO quite an achievement for the tint-shifting S21F (if lower Duv is what youâre looking for).
Very very subtle. But thatâs what I expect at this stage of the game among all these Nichia âgiants.â
No worries it hasnât been discussed at all. I donât understand how current supply works in tint shifting lights, but have measured outputs. Hopefully results would help for the experts here to explain whatâs going on:
2700k 100% (2 LEDs) = 1130 lm (4 amps for 2 LEDs ?)
3700k 100% (4 LEDs) = 900 lm (assuming mid point - 8 amps for 4 LEDs ?)
5700k 100% (2 LEDs) = 1370 lm (4 amps for 2 LEDs ?)
I am going to have to go back and re-test to see if I made an error at 3700k. Iâm puzzled why output would drop in the middle CCT range?
1900lm would be more likely at mid-point?
If this is the case, I really hope that there is a single CCT version of the S21F as the lumens are almost halved at 2700k or 5700k compared to the single CCT S21D.
Sadly, Iâve not seen any tracking movement on my S21F for a few days.
FWIW, my S21D 219b 4500k measures 1700 lm and S21D 519a 4500k measures 1900 lm. (EDIT 2/23 to correct error in 519a 4500k output.)
Iâve repeated S21D measurements numerous times but thatâs the limit. My TA lumen tube in general follows other reviewersâ measurements well.
BTW, Iâm starting to test the high CCT end and I think I will have some pleasant great news for this light! Simon has got a great bin on this end and we surely are the lucky 30 
.
Backing up the discussion to beginner levels, as Iâve never had a tint-shifting light:
â Do you click into a âtint selectionâ mode separatelyâŚ.and then click another mode for ramping lumen levels? Is that how it works?
.
How much lumenâs you received with your test equipment from S21D in max. turbo mode ?
(same 4pcs. N 519a , 4000K or 4500K)
This is from testing of the S21D 519A 4500k 8A CC. Review here.
âTesting was performed with the 8A CC driver option. Testing was inside, no cooling, 27C heat, and with a 4000mAh Samsung 40T 21700 battery. For each mode (group 3), I measured 2055lm, 850lm, 260lm, 20lm, <1lm. On 100% mode, the light managed >2,000lm until 105secs, and then slowly ramped down to 790lm at 10 minutes, where the brightness stabilised. Heat was a little too high for my liking. On 35% mode, the light sustained 850lm, and runtime was 100 minutes until low voltage warning started to flash at 3.05V.â