If anyone starts such a group buy, I will go for at least 25× 3500K
Even the FA3 tint bin that Fireflies is using is reported to be a little on the green side and requires a minus green filter to perfect. If we can source the FA1, FA4, FD1, FD4, I will be willing to buy at least 25.
I can organize a group buy if enough people are interested in the 3500k 95CRI LEDs. Goal would be 250. Just let me know if y’all think it is doable. They are estimated to ship in January.
We may have to go with this new Luminus LED for the BLF Lantern project, as apparently the Samsung 351 series in 2700K & 5000K are hard to order for the manufacturer of the lantern, but have not seen or tested this SST-20 emitter yet.
Personally I think it would be a good option. Going with CRI above 9080 really gets quickly into diminishing returns in terms of light quality. Going above 9050 quickly reduces efficacy. SST-20 is already quite inefficient, but I don’t think it’s too inefficient for this lantern…and for a CRI 95 emitter it’s good. It’s quite a bit smaller than LH351D which negatively affects its performance at high currents, but this lantern won’t have high currents. It’s already quite rosy and tint mixing will make it even rosier, we can expect CRI to suffer because of that. But is that going to make the light more or less pleasant?
As this emitter is only available in the 2700-4000K CCT range, this should be less of a problem. Mixing tint with a 2700K and 4000K emitter should give desirable result (maybe a bit on the rosy side between 3000K and 3500K).
I think, Nichia E21A could be still considered for the lantern (but it would need different PCB), as it has CCTs down to 2200K and 2000K with R9080 CRI (these are designated as R9050, but maukka measured R9 above 95 for the 2000K variant). Nichia E21A could be a good candidate for tri-channel mixing (e.g. 2000K, 3000K, 4500K), but I know, that it is only a wish of mine 
I fear that the E21A would give handling problems when reflowed by flashlight manufacturers, it is a delicate operation and I’m pretty sure they have no pick-n-place machines at Sofirn.
I’m all for the SST-20-W led, at these drive currents it is not that much less efficient than the LH351D. I think though that a few people regret that the colour temperature will not go up to 5000K anymore. Btw, I had understood from Barry (from a different discussion) that Sofirn is able to source the high CRI SST-20 leds.
Yes, the bare phosphor of the E21A seems to be pretty sensitive, so I would not try it myself as well.
Good news I had a talk with Sofirn a few months earlier about how high CRI can be good.
So I hope, if they can source those LEDs, they will
LH351D diffuse really well as it is. Even though SST-20 may work it seems like a compromise in every regard. Efficiency, CCT, and beam shape. Makes you wonder what is truly going on with Lumintop and Sofirn with some of these projects…
Yeah, I was really wanting the lantern to go a little higher than 4000K for sure. However, since it’s a lantern and not a flashlight, I think 4000K would still be acceptable.
I do hope they can source 5000K LEDs too.
If SST-20 is considered, 5000K is a very big step back (available only in ~65 CRI instead of ~95 CRI). If only SST-20 is used, this should be kept in mind.
Has anyone made more progress with throw numbers before/after slicing? I’m curious whether it’s worth the risk, or if these things are “good enough” with the tiny little dome on. I’d love to have some options that came even remotely close to the Oslon White Flat for throw with warmer CCT and better CRI.
@coherent, you’re asking about the sst-20 in general or in this particular light? I just happen to have pre & post slice throw numbers from an single led / reflectored light I built with an sst-20 two days ago if you’re just looking for general info.
Dome on the throw was 17,500kcd, after the slice and refocusing the little light was doing 33,200kcd. Tint and lumens both dropped ever so slightly.
Cereal_killer, I was curious about the SST20 in general, so your numbers are perfect. Nearly double the Cd and 40% more throw, sounds like I need to buy a few extras to try slicing. Do you have any advice for getting a good, clean result?
Wow, that’s quite a difference for an LED that’s already pretty throwy to begin with. How did you do the slice?
where to buy good SST20 4000k or 5000k? I can only find ones above bbl
Sorry just saw this, I did the washer method. Slice with a fresh new blade that you scrub with alcohol before using.
To be honest, had I spent the time focusing the emitter pre-slice that I did focusing it post-slice the difference would be less dramatic. I probably could of got the domed emitter focused a good bit better, just an amature best guess here but I’d say, if I was as meticulous with it as I was the sliced one I probably could of gotten it so the difference was <25% increase instead of nearly 50%.
I only spent 10min focusing it the first time around, only a few tries sanding the disk. I had set a goal of 40kcd for the light and I could see I needed something dramatic so I did the slice before spending much time on it.
Oh I forgot, I came back to this thread to ask what my options were for 5000k SST-20’s currently for sale in the highest output bin (the base 70cri version will be fine for this one)?
The highest bin available to consumers now is the L3 Flux Bin SST-20 5000k:
http://kaidomain.com/Luminus-SST-20-L3-DA-Neutral-White-5000K-LED-Emitter