LED color temperature issue

[Peter Berger]

It is because light meters respond different light types differently, right? Then in the situation of mixed lighting types, what can we do? Any experience to be shared?

Color meters like the Minolta II and III can read HMIs and Kinos pretty accurately because, unlike LEDs, they are continuous light sources with a spike of one color (green in both). They can be corrected easily because the meters are designed to read their green spike and there are gels (minus green) to correct for it. By contrast, the output of White Phosphor LEDs drop off to nearly nothing at three points (below 425nm, between 465 and 510nm, and after 625nm), so the Minolta II and III can’t read them accurately (Minolta’s test show they will be off by as much as 400 degrees Kelvin) and they can’t be corrected by gels because none are designed specifically for that purpose. This is why Kinos, HMIs, and Tungsten lights can be used successfully with one another where LEDs can not.


The dangers of using LEDs in mixed light situations was discussed at length in another RedUser thread. What I found to be most compelling in that thread was how Cinematographer Daryn Okada, ASC, discovered the hard way that neither color gel packs, camera white balance, nor digital intermediate timing can bring out the colors missing in LEDs because they are not there to begin with. Daryn‘s story demonstrates that, simply by nature of their discontinuous spectral distribution, even high CRI White Phosphor LEDs like the Rotolight ANova will never accurately reproduce colors on screen regardless what gels you use on them. ( see http://reduser.net/forum/showthread.php?59733-LED-lighting-for-interviews...thoughts for details.)

Peter Berger