Archived posting to the Leica Users Group, 2001/11/15
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At 10:30 AM -0800 11/15/01, Mark Rabiner wrote:
>A friend of mine assisted a Pendelton Woolen mills fashion shoot
>here on Mt. Hood.
>I recall he said they needed an 81c at the top, an 81b a third down,
>and an 81a
>more toward the bottom.
>I think they are spaced out 100 Kelvin apart.
>The 81a is 100 kelvin i think.
>Those are the filter 'd i used with my Nikons years back and when
>Ektachrome was
>so cold that a fella could die
The colour conversion filters represent a 'mired' or 'MIcro
REciprocal DEgree' shift value, not a degree Kelvin value. At around
3000 Kelvin the 81a gives you close to a 100 degree shift, but at
5500, it gives you close to a 500 degree shift. An 81A has a mired
shift value of 18, an 81B a shift value of 27 and an 81C a shift
value of 35. To shift from daylight to tungsten or vice versa
requires a shift value of about 110 to 140.
The KR3 filter talked about before has a decamired value of 3, or a
mired value of 30; K stands for conversion in German, and R is for
red, or reddish. A KR12 is the basic filter to convert tungsten film
for daylight use.
Colour meters are nice because the ones for photographic use are set
up to give you the filter requirements in CC for the cyan/magenta
axis and mireds for the reddish/bluish axis.
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com
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