(*1): LED CCT and tint shifting described clearly in the datasheet provided by Nichia and I also put the link to it in the product page. CCT/tint shifting occurs in any LED, the higher the working current range, the higher the swings. This explains why mid power and COB LED has minimal CCT/tint shift - their current range is limited compared to high power LED. COB and arrayed LED also has less shifting because they have more uniform color separation averaging over angle.
You already have the most tightly binned Nichia: 3 steps and R9080. The higher the CRI the less CCT/tint shifting it will be. Manufacturers always measured the binning CCT at certain current and then provide additional current and temperature shift curve in the data sheet.
To get the most consistent color you better use (lots of) mid power LED (within spec current) or fix the current and use PWM to alter brightness.
(*2): Manufacturers use big calibrated integrating sphere with at least 1 meter diameter. Most of us don’t have such equipment and I consistently put any LED I sell to Maukka since he’s the only person in this community who has the closest equipment and setup to manufacturer’s standard. I’m sure many flashlight manufacturers own such equipment but I have no access to them. LED’s output CCT/tint vary with viewing angle. And E21A is one of the most consistent LED about it.
(*3): could you please kindly take a close-up macro pictures of both LED modules? Your LED was from the same reel and batch tested by the “other” reviewer. I also used this 5000K LED for hundreds of cafe light, streetlight (no optics but PMMA cover), Jet-UE21A, Wizard Pro, and Tiara Pro mods. And I never heard anyone bought those modified lights from me complained about the 5000K E21A horribly colder than expected. So, if you think your LED is defective/different I’m also very curious about it. Just let me know if you’re interested and we can start an investigation openly. I always feel bad when people disappointed with my stuff/service.
(*4): I only provide manufacturer’s data (there’s link in the product page) and add some more missing data not covered in the data sheet which is individual CCT/CRI measurement for each CCT class. So far, I haven’t seen any web store providing this data. I also states each reel binning code, every time I get a new one.
[Clemence]