Re: Studio Lighting (Whoops)
Re: Studio Lighting (Whoops)
- Subject: Re: Studio Lighting (Whoops)
- From: "Ernst Dinkla" <email@hidden>
- Date: Fri, 20 Sep 2002 13:52:02 +0200
A quote of a C.D.Tobie message by Harvey:
>
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
>
*********************************
It is hard to get Ott-Lite compact fluorescents in Europe and a 230>110 volt
converter isn't easy either.
Since a week I have some True-Lite (or True-Light now) compact fluorescent
lamps of 15 W 230 V with an edison fitting. A Minolta colour meter says 5700
K, the SpectroCam says around 6000 K as indicated by the manufacturer. The
curve shows the peeks at 400, 440, 490, 545 (highest), 610, + 2 lower ones
and at approx 1/3 of heigth of the peeks a continuous output. Is that
similar to the Ott lights ?
Duro-Test was mentioned as the company involved but this one is made in the
EC, could be Greece.
Ernst
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