Lumens affecting tint, DUV

I was easily able to find info about tint, DUV, etc for various LEDs.

But I can’t find information about if/how lumens affect tint & DUV.

Will the LED tint, DUV, etc usually be pretty constant across lumens?

There is often a shift in DUV at different current levels for a particular LED. However, this behaviour depends on the LED model. An example is increasingly +ve DUV as the current decreases on SST-20s.

Is there a good place to find this information?

I’m especially interested in 519A, 219B.

You can usually find this in the data sheet: google “nichia 519a data sheet” (for example)

Direct link: https://led-ld.nichia.co.jp/api/data/spec/led/NVSW519AT-E(6102D)R70%20R8000%20R9080.pdf

Check out page 32 and onwards: “Forward Current vs Chromaticity Coordinate”

> Check out page 32 and onwards…

Checked out, sorry I am not smart enough to figure out what that means.

The CRI remains the same but the heat from more current (more lumens) affects more than one characteristic of the emitter. Tint and DUV are basically the same thing…perhaps you meant the CCT (color temperature) and the tint? They do both generally change a bit through out the current/heat range. With enough heat there’s also some derating in output and resulting changes in temp/tint but that’s the kind of thing you can see in measurements, not so much by eye…I mean it’s real but the usual changes are what you’ll notice.

The manufacturers’ data sheets are the best place for this. Tests and reviews (esp with Opple data) aren’t the most reliable sometimes but they do have value (like beamshots…they can be all over the place but the more the better). There are lots of comparative graphs in these sheets, so you just need to familiarize yourself with the terms use (voltage, various temperature points, current/amps, etc etc) and then look at what the two or three legs of the graph are showing you. The easiest to relate to is how most often the color temperature may increase/get whiter with more current, and decrease to where it’ll look warmer and/or bring out undesirable tints at lower currents. Using a ramping like like one with Andruil and an emitter that is known for more dramatic shifts will make this easier to learn…then you can compare what you’ve experienced with your eyes to what the data sheet tells you.

The data sheets look like a complex jumbled mess when you first start to look at them, but they start to make sense as you read, re-read, and study them just a little…and then you will see just how much great info the manufacturers share with us from their top level testing. Gotta take into account flashlight parts after the fact, though, like how reflectors and optics and lenses may change things up a bit.

Sure you are.

About chromaticity: Chromaticity - Wikipedia

“Tint” is represented on a chromaticity graph by means of coordinates. These coordinates, the tint, will change with current. The “Forward Current vs Chromaticity Coordinate” part of an LED datasheet is this information.

Various LED tests on BLF illustrate how tint shifts with current. Here for example is a chart presented by Maukka in a test of Lumileds Luxeon Z ES 5700K CRI90 (LXZ2-5790). (thread link)

Usually LEDs have a higher DUV at lower currents. Many LEDs are perceptibly green or yellow at low currents but become more neutral and pleasant at higher currents.

This is why LED lights with PWM can offer a better tint at lower brightness. The LED is still seeing a relatively high current, it is just being pulsed on and off very quickly to change the perceived brightness.