Re: Studio Lighting (Whoops)
Re: Studio Lighting (Whoops)
- Subject: Re: Studio Lighting (Whoops)
- From: SKID Photography <email@hidden>
- Date: Thu, 19 Sep 2002 13:09:52 -0400
- Organization: SKID Photography
Whoop! pushed the wrong key...sorry finished post below:
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I'm surprised some of the more knowledgeable people on this list have not spoken up yet,
but
here goes (hopefully I won't goof this up too much).
As I understand it, the 'Solux' bulbs deteriorate from their given color temp relatively
quickly, and therefore are not a good long-term choice.
And as far as buying 'daylight' fluorescent lights at the hardware store. There is more
to the
'correct' color than a color temperate. I it's called the CRI (Color Rendering Index).
Below is an old post from CD Tobie (I hope he does not mind this being reposted).
Harvey Ferdschneider
partner, SKID Photography, NYC
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CRI measures how evenly the light is distributed at all points in thevisible
spectrum, something a spectrophotometer can see, but the eye can't. A
"triphosphor bulb" like most daylight balanced bulbs, accomplishes the
balancing with emissions at three points in the spectrum, so its spectral
graph looks like three mountains on a plain. How well each of thesemountains
line up with the three color cones types of the human eye, and how big each
peak is, determines how well balanced the bulb is.
But a better over all result can be obtained by using multiple phosphors for
each cone location, to balance (for instance) a blue phosphor that is a bit
to cool, by adding a warmer one, making a two peak mountain that has thesame
area but a wider base, and lower peaks, offering a broader range of wave
lengths as well as a more accurate tuning to the eye's cones. There are also
smaller secondary spikes caused by the phosphors, and taking them into
account in the phosphor balancing makes for even more accuate color tuning.
Finally you end up with a bulb like Ott-Lite produces, where the overlapfrom
the base of each mountain is continuous, offering a substantial level ofbase
illumination at all visible wavelength, and many small peaks above this
background level, carefully balanced to have the proper effect on the eye's
cones. Ott-Lite is not thrilled to have people reverse engineering their
products and describing them in this type of detail, as they are obsessed
with others stealing their formuli. But this particular market is not one
where saying "ours is mysteriously better" will suffice, and explaining why
is something that has been left up to people like me.
C. David Tobie
Design Cooperative
email@hidden
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