Preferred Δuv?

LED Flashlights – General Info
21

great link! thanks for the info
this pic is from that source:
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Im suprised to see DUV –0.0150 is preferred by the test subjects. That is lower DUV than most sw45k I have seen tested.

for those confused by the DUV term, it is just a new word for an old idea. We used to say Below the BBL or Pink Tint, but there was no numeric reference to compare the amount of pink nor how far below the BBL was being discussed.

DUV is just a way to put a number on the amount of pink tint (or green if above the BBL), and to give a reference for how far above or below the BBL the tint of a light measures, numerically.

example of some of my sw45k LEDs with differing amounts of Pink Tint
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(I added the DUV values measured w Opple)

here are the individual plots of those two DUV values:
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22

What Bob said. And what thefreeman said.

Depends on the CCT, but I typically like low duvs… like –10 to –15 mduv (but even –5 is okay).

It’s why there’s a phrase about how positive people “see the world through rose-tinted glasses”. A pink tint generally makes things look more pleasant. It’s similar to how people turn up the bass to make music sound better, boosting the low frequencies for a more enjoyable experience… but with light instead of sound.

23

This topic has piqued my interest, does anyone know a source for 2700k and or 4000k LEDs with c. –0.015 duv values?

24

I buy my 219b LEDs from Andy Zhu

here is a thread that shows one sw27 compared to one sw30… (the sw30 has lower DUV)

that thread also has tests of several sw45k, and a comparison of two different sw35 (they are not identical)

we cannot specify DUV when buying, but there IS a trend imo, that sw30 and sw45k have lower DUV than SW27, sw35 and sw40

25

I don’t think you’ll find any LEDs with a duv this low, except maybe an overdriven sliced sw45k for ~4000K. But you can achieve this sort of duv level by CCT mixing. For example E21A 2000K + 4500K in my tint ramping IF25 :

I used 4500K because I only aimed for –0.01, but 2000 + 6500K gives 3700K ‐ 0.0120 at 0.7A per LED, it can probably reach –0.015 at higher current, though Maukka’s E21A data isn’t accessible anymore so I can’t calculate it.

The only manufacturer offering E21A lights in CCT mixing configuration is Emisar Noctigon I think, unfortunately they don’t have E21A 6500K, only up to 5000K.

26

fwiw, E21a IS available in 6500k from Hank

27

Ah, secret menu then (email order), good to know.

28

That is the chart I was looking for the other day and could not find! Tint ramping is way over rated IMO, but tint mixing is not. Hands down, the best DUV light I have is a D4V2 with 2 sw-45k and 2 sw-35 219b’s. The light CCT is right around 4000k and the DUV is the most amazing negative level I have ever seen and it holds throughout the brightness range! I have a D4V2 with 3500k E21A’s that I really want to swap 2 of the emitters to 4000k as the light is a little warm and yellow for my tastes. I also have a KR4 with swapped SST-20’s at 4000k that is an SST-20 outlier with really good DUV. I am not sure of the bin of the 20’s, but I have no others like them. They came from a Sofirn light initially. My gen 1 FW3C SST-20’s are very close but not as good at low current.

29

What is the DUV value from your Opple?

30

It is really good, this is at very low drive.

31

Thanks!
DUV –0.0070 at 4000k, from a mix of sw45k and sw35 sounds nice and pink.

re
E21a 2000k mix w E21a 6500k, when combined at 3700k, produce a DUV of –0.0118 (thanks to maukka):
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32

Jon, it really is pretty good. At higher drive currents it becomes more obvious. I always check at fairly low drives as most of these types of lights are night lights for me. That E21A mix may be even a bit excessive.

I have a D4V2 with E21A’s @3500 and it is to yellow for my tastes. I am thinking of changing 2 of them to 4000 or 4500k.