Looking a a few 730nm LED Datasheets a part of their spectrum are in the Visible range which would be what we would see, just like an UV LED also emits in the visible range.
Depends on the lighting and tint bin. The sw45k seems fairly tightly binned and most people would say the SW45k is pink, but it is blue compared to warmer lights or at night. I have had 3 bins of the SST-20 4000k and they range from yellow-green to white-blue-pink in tint.
Interesting. Our Bundesamt für Strahlenschutz BfS gives a range of visible light up to 780nm. Is this a mean/max thing? Or don’t I understand the photopic luminosity function (likely )?
If I was to make a guess, while those LEDs still have a significant blue spike and overall different spectral makeup than a blackbody source the difference is insignificant compared to what a lower-Ra LED or florescent would have. The latter two have HUGE gaps in the spectrum that are underrepresented vs blackbodies. Since color of an object is determined by reflected light, the slight differences in intensity of some wavelengths doesn’t matter as much for accurate color representation (since much of the light is being absorbed anyway) vs a segment/segments of the spectrum being extremely low relative the others.
About OP’s question: we do not see 450nm very well, our eyes are just 4% as sensitive to it as our peak at 555nm. So a spike at 450nm is not obvious. The blue is needed for natural colour perception, but the amount appears not very critical, although real snobs may see it.
Same for deep red, we hardly see it so it is not critical for how we perceive colours, but it does help for that last tiny bit of colour rendition.
In general: our machines detect light way better than our own detectors: our hopelessly primitive eyes. It must be noted though that we have brains that are extremely capable of squeezing every last bit of colour information out of our very poorly functioning eyes.
Lovely answer, thank you. Coming to flashlights as a bit of an objectivist audiophile, I know how controversial measurement of aesthetic machines can be. I would love to see the incandescent snobs defend their preference in a “blind” test.
I wonder if there will be any LEDs soon that fill in that last bit of red. Seems like sunlike do get rid of the blue spike.
There is another reason to not want that blue spike, not colour rendition but the influence of blue light on our mood. There is some research on that, the effect may not be huge or worrying, and the definitive facts are not out there yet, but since it is picked up by public opinion as real and dangerous, led manufacturers have no other option than respond with leds that do not have that blue peak.
Personally I have found blue blocking glasses to help me sleep and I know this is a fairly well validated fact. However for flashlights, because you can usually control the amount of light so easily, I don’t think it is as much of an issue. Also, IIRC, blue light impedes melatonin production but only if it enters the eye from above. So I drive my GF crazy by always using flashlights around the house before bedtime and turning off overhead lights.