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Another issue is that many LEDs have peaky spectra. This makes cool white harsh and warm white dingy. This isn't limited to cheap products, as producing a fulle
by Zak 9y ago
Another issue is that many LEDs have peaky spectra. This makes cool white harsh and warm white dingy. This isn't limited to cheap products, as producing a fuller spectrum with LEDs is less efficient.
I'll take the efficiency hit for better light; the most common measure used, printed on the packaging of some bulbs is CRI (color rendering index). It's based on blackbody radiation, so incandescent bulbs and sunlight both have the maximum score of 100. The average unspecified LED is in the 60s and sodium vapor lamps are negative. 90 is good for an LED, and 97 is the highest I've heard of someone testing in an LED[0].
CRI isn't the whole story on color quality, and it's possible to have high CRI with off tints or even a peaky spectrum outside of the specific colors the CRI standard tests, though the latter doesn't happen in practice. Several newer standards for measuring color quality exist, but are unlikely to be listed on a light bulb label.
[0] http://budgetlightforum.com/comment/1096106#comment-1096106 http://budgetlightforum.com/comment/1096106#comment-1096106
- oasisbob 9y agoAgreed! It took several tries to get LEDs which worked well for vanity (i.e. Mirror) lighting. I thought it was a simple matter of color temperature - so wrong! High CRI strip LED arrays are surprisingly hard to find. The end result was worth it though - skin looks natural, and the nearest commercial version is upwards of $800 - and I'm not entirely sure they got the CRI right.
- w458cmau 9y agoWhich solution did you end up with?
- oasisbob 9y agoI ended up with a strip from colordiode, they're available on ebay. Was described as CRI>95 3000~3200K SMD2835, 90/m. Came with a pretty decent datasheet, seemed well-characterized. Cost was ~ $10/meter. They were responsive enough to include a few samples of other color temperatures with the order when I asked nicely. The housing used was extruded aluminum u-channel by Torchstar (U05, semicircular), very nice clean finish. Available on Amazon. Like I mentioned, this was for vanity lighting - there's a full length mirror in the closet that's wedged on the wall between a closet door and a window. Not much room for anything else. Hung two vertical strips, ~ 4ft long, on each side of the mirror. Light ended up soft, diffuse, and flattering - but still directional enough for good modeling. Significant other couldn't have been happier.
- dreamlayers 9y agoYeah. The best example was lighting all my clothes with LED lights. Colours seem obviously messed up. Some colours are emphasized while others are suppressed.
- Paianni 9y agoLow pressure sodium lamps (SOX) are negative, -44. High pressure sodium lamps (SON) are positive, +20.