I may not have explained completely either. I’m not aiming for a meter-verifiable value of 0.000 duv. I’m aiming for something which I think looks good in person… like ~4500K with negative duv.
Adding a minus-green filter is a pretty common modification when using SST-20 emitters, LH351D, and sometimes others. The 89% transmittance value given earlier is a bit generous though… the range I generally see is 70% to 86% transmission, and I’m expecting to need roughly an 80% model to get most of my greenish lights down to a nice-looking tint.
As is, when I use this SST-20 FW3A outdoors, the grass looks nice and green… but so does the sidewalk. And when I point it at purple-colored objects, they turn blue. When aimed at objects with several shades of green, I find it difficult to tell the shades apart. It’s all lemongrass. So I’m hoping a filter can fix that.
I recently ended up with a D4 SST-20, which demonstrates the low-mode tint issue pretty vividly. If I put it in stepped ramp mode, steps 1 to 4 are green while steps 5 - 7 are white. If I make it go back and forth between steps 4 and 5, it looks like two different lights… green, white, green, white, green, white. Because of this, I’m tempted to convert it from a FET+1 light to FET-only, to make the tint usable below 150 lm.
… except for hitting the tint sweet spot which studies have found agreeable to the most people.
It can be tint-corrected with a minus green filter, but after filter losses it ends up making fewer lumens per amp than the aging 219B.
It’s definitely old, but there are good reasons why people still prefer 219B over 219C, why people prefer XP-G2 over XP-G3, and why SST-20 isn’t universally loved. In the quest for ever-increasing efficiency, several different LED manufacturers over the past few years sacrificed optical quality for higher total output.
The changes, like in Cree’s current-gen emitters, make a lot of sense for use in lighting fixtures where the LED is meant to run near full power all the time behind a diffuser. In that sort of device, the Cree rainbow doesn’t matter and neither does current-related tint shift. It only needs to look good when integrated and running at the recommended power level.
That sucks a bit for flashlight purposes, but flashlights aren’t a big enough market for LED companies to really care. So we’ve been using a lot of old stuff lately instead of always adopting new tech.
…
In any case, the point I’ve been getting at this whole time is: There is no One True LED. Different people prefer different lighting, and that’s okay.