It’s my understanding that even the non-RGB Philips Hue ‘warm-to-cool’ bulbs don’t perform well in R9 measurements. Are there any smart lights you know of that combine high R9 values with adjustable color temperature and brightness?
From what I’ve read, mixing a low-Kelvin emitter and a high-Kelvin emitter with solid Ra measurements can create light that maintains high CRI across color temperatures by adjusting the power ratio between emitters. This is how photography and cinema lighting panels allegedly work. Does a light bulb using this setup exist? I haven’t had luck finding one.
This is a fascinating question. A light source with two emitters (e.g., 6,500 K and 3,000 K) will have good color rendition at each extreme but can fall off the black body locus when blended at intermediate temperatures like 4,000 K. This can result in worse CRI at those midpoints because the combined wavelengths may seem unnatural.
For more accurate tuning to the black body locus, you’d need at least three emitters (red, green, and blue) combined in a way that replicates natural color rendering. Some lights like Philips Hue and Ketra lamps use this design, but most tunable white sources do not.
@Oak
You mention RGB emitters can recreate the black body locus, but doesn’t RGB lighting perform poorly for illuminating objects? RGB light fools the eye by creating perceived colors, but wouldn’t an orange object, for example, appear washed out if it’s not reflecting true orange wavelengths? TVs use RGB directly, but lighting seems to need full-spectrum emitters to ensure objects reflect their true colors.
@Cameron
Good point! The human eye perceives colors through blue, red, and green cones, so RGB can simulate colors directly. However, you’re correct—if you’re lighting an object, RGB light might not accurately reproduce its color since there’s no true orange wavelength, for example. Full-spectrum lighting is better for illuminating objects and creating accurate reflections.
@Oak
That makes sense. I recall a classroom demo where an RGB LED set to ‘orange’ failed to illuminate an orange marker on a whiteboard because there was no orange wavelength present. A full-spectrum light, however, revealed the marker perfectly. RGB seems great for displays but less suited for environments where object color fidelity matters.
@Oak
Lumitech is one company doing this right. They offer a 3-emitter design (RGB) that achieves a CCT range of 1,800 K to 16,000 K. Their lamps are highly customizable.
Just to clarify, CRI (Ra) and R9 are separate metrics. CRI measures the average reproduction of 8 pastel colors (R1-R8), while R9 is for saturated reds. It’s possible to have a high CRI with poor R9 values, which is why some people prefer using TM-30, a more comprehensive standard.
Tunable white systems typically share the qualities of their two emitters. If there’s a drop in intensity at certain points, it’s often due to poorly designed dimming rather than diode issues. I have video lights that maintain 95+ Ra and R9 across the full CCT range, but they’re panels, not bulbs, so they pack more small diodes into a compact area. Replicating this quality in a bulb is harder.
@Remy
Thanks for explaining that! I’ve run into a lot of ‘high CRI’ lights with poor R9 values, which sent me on this hunt. I’m looking for something that performs well at 1,900–2,200 K at night but can also switch to 3,500–4,000 K during the day. Ketra lamps seem to fit the bill but are pricey—about $100 each—so maybe best for a desk lamp setup.
I’ve installed Philips smart white lamps, and I think the light quality is great. However, I don’t love the app interface. For my home, I prefer lights like these that adjust temperature through dimming:
Yes, you can find high CRI color-changing smart bulbs, but they’re usually for professional lighting and not common for residential use. Check out the Astera NYX bulb.