Question pls. What is the source of that green tint shift? I thought I read somewhere (from you?) that it is from light that travels horizontally along surface of phosphor (instead of vertically/forward) and therefore crossing a thicker layer of phosphor?
And why does a dome make it worse? TIA
Thinking about S2+ Copper with best tint in 4500k (or better 4000k?). Is it 219 or B35AM? Also howās 219 at 3000k and 2700k? Iām a sucker for 3000k lately 
219b vs B35AM - They are different, not one is better than the other. The 219b 4500k is probably the one that hobbyists have wasted the most ink on, so personally I think itās the starter LED for tint snobs. Just to set the baseline for comparison. That rosy tint is unique and rarely seen in any other LED.
B35AM is more creamy yellow, probably partly because my two B35AM lights, H2 and M21B, both use reflectors. The advantage of reflector is that the light has a very wonderful and useful throwy beam. Both measure 900-1000 lm so the higher output is very useful. The M21B with B35AM 4500k is one of my most favorite lights for walking. Stay cool with good sustained output.
Iād say get both. But if possible get 219b 4500k in M21H. 219b has lower output so a quad LED makes it much more useful if you need better output. I have 219b in 3500k and 2700k also, but my preferred range is 4000-4500k.
If you happen to have M21H in 4x219 configuration could you share a front picture? Wondering how TIR optic look like and couldnāt find a picture on the internet.
Yep, I think that explains it.
The dome is known to reduce the conversion of blue into lower-frequency photons, which is why the tint turns warmer upon dedoming. Perhaps the increase in CCT is non-uniform across different angles, exacerbating the tint shift.
I am too annoyed with reddit to find it, but there was a recent post on tint comparisons between 219B and 519A. The result was that the 519A has better/rosier tint in every CCT other than 4500k! So I donāt see any reason to consider 219B for lower CCTs, losing out on tint and output.
Iād recommend B35AM. From what Iāve read there is quite some variance in the tint of 219B, while B35AM is more consistent. The B35AM is slightly less rosy than 219B, but still evidently rosier than 519A or a true neutral tint. It has a lot more output than 219B.
Personally would not recommend the quad LED solutionāit loses too much throw (equivalently, makes a light way too big) for no good reason, when a single higher-powered FFL707/909 emitter could have done the job better. The throw loss is inevitable because extreme diffusion is needed to fix the doughnut hole artifacts. Plus even 4x219B produces pretty anemic output for the light size class.
Really? I donāt have 519a to compare. But the 219b in 3500 and 2700 do have less negative Duv, in the negative -0.0020-30 range. The 2700 practically looks RED. Honestly at this lower CCT, I think the CCT dominates so much and thatās why you hardly see any discussion about rosiness in lower CCT. IOW & IMHO itās a moot point.
219b 4500k is what Iām talking about though, and the one I recommend. And here, there is no other LED that looks the same or has that unique rosiness (other than Nichia E21a). Thatās why Iām suggesting it. @Teppka is this what youāre looking for:
Agreed. Tint seems most noticeable at the mid range of CCTs, 4000-6000K. Iām bringing up this comparison because a discussion around 219B 2700K/3000K was initiated.
The B35AM is just 4xE21A, but with better tint consistency.
Does it accommodate same TIRs?
Are you asking about M21H with 219bx4? Yes it accomodates all the optics below, but has black holes with 3Ā° and 8Ā°. It comes with 12, so I would only recommend adding 24 and 36 if better rosy tint is the goal.
I like M21H a lot btw. Proper thermal regulation and, for me, so much better side switch than the ones in S21F, M21E, M21F (terrible travel and feel). One of the best Convoy hosts IMHO.
And nowadays I will always ask Simon before each order if he could include a green-reflection AR lens (for free). My last two Convoy lights came with purple reflection lens and itās a nuissance to have to ask for replacement.
I asked him and he said that nowadays all lights should come with green AR as standard but Iām not sure how it goes. My M21H and S2+ came with purple AR while S6 came with green AR. T3 comes with no AR glass. So Iāve ordered green AR coated glass for them all.
What Iām wondering is, does S2+ copper has any better sustainability in terms of heat management than S2+ aluminum. Heat conductivity does not mean better dissipation. Also copper ones have full coating so I donāt know how good it is at dissipating heat.
I vaguely remember seeing a long discussion on this, heat conductivity vs dissipation, involving the Wurkkos TS10 . @jon_slider might/should have some good information.
Difference is likely too insignificant to be measurable/noticeable without specialized equipment. My main complaint against copper is the weight and softness (extremely easy to damage/deform severely after one drop).
Copper, Titanium make absolutely no practical sense in flashlights compared to aluminum. Yet we buy them nonetheless
I just like these metals, canāt do anything with myself.
Thanks for the chuckle. Both my M21E and M21H came with purple AR lenses. Our beloved Convoysā¦ like a box of chocolate. 
Simon orders them in bulk and said sometimes supplier screws up. Which I totally believe. So all I do is leave a note while ordering that I need green AR coated glass just in case.
This Cu/Ti combo actually makes a lot of sense. The copper is used around the heatsink area for obvious purposes, which is also the area that takes the least damage from drops, which tend to damage the bezel+tail+threads the most. No problem here because these damage-prone parts are Ti.
BTW, with one of the finer sides of a nail buffing block itās very easy to remove AR coating from purple coated lenses without scratching the glass. Iāve done this and have both purple and green lenses; removing purple makes a very nice difference in duv, while going from uncoated to green has no noticeable effect.
Itās interesting to note that the rosiness of these FFL Rosy LEDs could also be observed in nature, during what shutterbugs refer to as the āgolden hour.ā As the sun goes down to horizon, blue light is scattered, while longer wavelengths like red and orange reach our eyes. The result Iām sure youāve seen is that pink sky or pink cloud. That color rendition is similar to what these FFL LEDs look like, to me an extremely pleasant and beautiful tint.
Not surprising that this appealing tint is all the rage these days. Unique and unprecedented.
Bare copper should be (quite a lot) worse at radiating heat than anodised alu. It is superior for heat conduction and for dissipation, but not for radiation - no idea how much of a flashlightās heat is shedded via radiation though.
