Reply To: Kelvin discrepancy at higher values

[Michael Okincha]

#49135

Hi Aaron.

Thanks the excellent measurements. The short answer is yes, your readings are what we see with the IM100 meter.

I assume you are using a color-temp adjustable LED light source. All white LEDs are made by putting a phosphor coating on top of a blue LED. The blue LED’s light causes the phosphor to emit yellow light, and the combination produces white light. The blue LED’s light spectrum is very narrow – less then 2% of the range of colors visible to humans.

Despite our best efforts, that blue light occurs right where our blue sensor’s spectral response is a little inaccurate. The sensor’s error is only a few percent from ideal, but the blue LED’s power is all concentrated in a narrow range. So it’s natural that as the LED’s light becomes more blue, the color temp error increases.

We plan to release an updated version of the meter by the end of the year. Among other improvements, we have increased the color accuracy for cool white LEDs.

Regards,
Mike