White light sources (and their quality)
(continued thread)
white leds not great way illuminate prints because not near full spectrum light sources. "white" leds blue or violet leds green or yellow phosphor added neutral - have little light in other areas (especially red). high end white leds getting closer full spectrum - available, , not yet widespread.
cheap fluorescent lamps tend have few "spikes" of light , have wavelenths entirely missing. "full spectrum" fluorescent lights getting better, , cheaper - still not comparable in quality tungsten or daylight.
spectra measured x-rite colormunki , argyll cms spotread utility. multiple readings averaged, normalized , plotted in microsoft excel.
[ updated dec 16, 2012 add white led4, recent cree flashlight led ]
[ updated may 27, 2013 add samples 2 led lightbulbs ]
that's cool info, chris.
are of leds tested using cree xr-e led? that's what's in fenix ld10. can definitively looking in spectroscope has lot smoother spectrum bumpy ones you've shown in second diagram. have bump in blue, dip around cyan isn't deep , power in green through red quite high. cuts off pretty quick @ around 640 nm, sunshine seems go 650 (after eyes cut off ).
i found this:
the chart on page 5 matches yours 5000k-10000k cct model led.
i don't know specific model have in flashlight, looking @ chart i'd guess not one. have pointed out, eyes aren't calibrated quite spectrophotometer.
-noel
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