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"spiky" light outputs


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#1 DS Williams

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Posted 20 May 2009 - 12:51 AM

What exactly is the problem with a lighting instrument that emits a spiky output, like an LED or some HMIs? Or magnetic ballast flourescents?

Will certain colors seem brighter or more accentuated due to the saturation of that wavelength present in the light itself?

Do our eyes correct for these spikes, more or less?
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#2 Karel Bata

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Posted 20 May 2009 - 08:01 AM

Do our eyes correct for these spikes, more or less?

It's a good question. If the spilke is there, why do our eyes not see it? Here's the spike (and that is a very generic LED!):

Posted Image

Here's film:

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and here's you:

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Notice the differences? To the human eye a spike at 550 will read as an equal amount of red and green (yellow). To film this green is smack in the middle of the green peak, so it will read as a strong green - hence the green cast!

And yes, your eyes/brain will adjust better than film or video but not perfectly. You still can't see colors that aren't there. For instance, you'll get used to the yellow of a low pressure sodium motorway light, but all blue cars will look black. There is no blue in the light to see - though your headlights will add some.

And here's video (though there are many different flavors):

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Yeah, right... :(

And while I'm here, here's my favorite film emulsion of all, Polaroid SX70:

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You'd think that with those huge dips in the sensitivity at 500 and 600 you'd get a crap image (a rainbow would have dark bands!) but to me SX70s were the most beautiful format ever

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more here: http://www.flickr.com/groups/sx-70


Now, this post is not meant to be the definitive answer to this topic - just my current understanding of it, which I think is reasonably accurate. and I welcome any corrections. :D
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Rig Wheels Passport

Tai Audio

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