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Comment by fmajid | Hacker News Reader

Not to mention the Color Rendering Index (CRI) metric Ra does not weigh the R9 (deep red) so many forms of lighting don't try to render it correctly to save costs.

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This is truly an (accidental?) setback of color reproduction as it has progressed over time. For LED lights R9 is also crucial for skin tones which makes it so bad to just leave that out. Now, the mass produced LEDs are even optimized for CRI at all are virtually all excluding R9, which may be one of the main quality issues that many people perceive with LEDs vs eg incandescent. There’s of course more to it but R9 probably has a disproportionate effect for being a ”minor detail”.

what's the alternative metric to look for as a consumer?

It is not reported often by the manufacturer, but SSI and TLCI numbers can be a better metric if available. They are used by the Broadcast/Photography community to match the spectrum's similarity to Sunlight.

Few bulb manufacturers even bother to report CRI, unless it is decent (CRI > 90). If CRI is not reported, you can be sure it's bad, 80 or less.

Unfortunately, there isn't really a way for a consumer to know short of buying a spectrometer like my Sekonic C-800 Spectromaster.

For illustration, I have uploaded a few readings here, mostly flashlights, not LED bulbs: https://majid.info/images/reddit/spectro/

If you look at the Zebralight SC64c LE, for instance, it has an excellent Ra of 92, but only 75 for R9:

https://majid.info/images/reddit/spectro/ZL_SC64cLE/SC64cLE_...

"C-800 Spectromaster" is exactly how specialized devices like that should be named.

It does sound a bit like the Boeing C-17 Globemaster III my uncle worked on...

Only 17? This one's 783 better!

Sekonic video on the C-800 (and the standards it can measure CRI, etc):

* https://www.youtube.com/watch?v=_oXqWlUuSNA

TM-30 for general illumination, since it's based on human perception, not on what's best for a sensor like TLCI. Particularly the overall Rf and the h1 bin (skin tones) will tell you the most. Also color temperature accuracy if you want to match it with natural lighting and other lights.

Ugh. CRI doesn't include R9, so CRI 100 doesn't mean 100% replicating sun light / Incandescent Light bulb? Are there any LED that actually does a decent job in colour representation?

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