Measuring colour temp at home

I have not used it, however Expodisc does just this.

I personally shoot in RAW and if the colour temp is not right, correct it in
post production. Adjusting the colour temp does not reduce the quality of
the pic.


"Tunku" <stuartggray-nospam.RemoveThis@dsl.pipex.com> wrote in message
news:Xns9891D2E29AB9E13D71@127.0.0.1...
> (ONE) I would like to approximate the color temperature of various
> light sources. This is for use in general photography.
>
> (TWO) I would also like to approximate the color temperature of the
> ambient light in a room after it has been reflected by the various
> surfaces.
>
> Is there a way to measure these color temperatures using the sort of
> equipment which might be found in a home workshop of an enthusiast?
>
 >> Stay informed about: Measuring colour temp at home 

Tunku wrote:
> (ONE) I would like to approximate the color temperature of various
> light sources. This is for use in general photography.
>
> (TWO) I would also like to approximate the color temperature of the
> ambient light in a room after it has been reflected by the various
> surfaces.
>
> Is there a way to measure these color temperatures using the sort of
> equipment which might be found in a home workshop of an enthusiast?
>
Photograph a neutral grey target with a digital camera using RAW mode.
Use RAW converter software that has a white balance colour-picker on the
image of the card, and read the white balance that the raw converter
calculates. That doesn't allow for quite a few variables, but assuming
that you're after a rough and ready solution for photographic use,
should do the trick.
 >> Stay informed about: Measuring colour temp at home 

On Wed, 06 Dec 2006 20:43:51 GMT, Tunku
<stuartggray-nospam RemoveThis @dsl.pipex.com> wrote:

>(ONE) I would like to approximate the color temperature of various
>light sources. This is for use in general photography.
>
>(TWO) I would also like to approximate the color temperature of the
>ambient light in a room after it has been reflected by the various
>surfaces.
>
>Is there a way to measure these color temperatures using the sort of
>equipment which might be found in a home workshop of an enthusiast?


If I were going to play with this idea, I would take a picture of some
neutral object under sunlight, then take a picture of the same object
under the light in question. Use RAW conversion software, play with
the software color temperature adjustment until you matched the
original color from the known source.
 >> Stay informed about: Measuring colour temp at home 

Tunku wrote:
> (ONE) I would like to approximate the color temperature of various
> light sources. This is for use in general photography.
>
> (TWO) I would also like to approximate the color temperature of the
> ambient light in a room after it has been reflected by the various
> surfaces.
>
> Is there a way to measure these color temperatures using the sort of
> equipment which might be found in a home workshop of an enthusiast?
>

Sure! Get a MacBeth ColorChecker and use your digital camera
with on-camera histogram mode, such as my Canon 30D. Set it
for a fixed WB mode, like Daylight. Photograph just the area
of the Color Checker with the Red, Green, and Blue patches.

Look at the histogram. From the values on the histogram
you can calculate the color temperature using a calculator
and the appropriate formula. Actually, you will get two
measurements from two pairs of ratios, and if they differ,
you have light that did not come from a plain "hot"
source.

How practical? I'm not sure.

Alternatively: using the same camera, you can play with
various settings, and if one is right (the three color peaks
at the same spot on the histogram) you know the temperature.

Doug McDonald
 >> Stay informed about: Measuring colour temp at home 

I just realized that my reply about using red, green, and
blue patches with a digital camera was silly. You would need
that only with a single light meter (and it will of course
work.)

It's too late in the afternoon for my brain.

With a digital camera, you just use a white spot.

Doug McDonald
 >> Stay informed about: Measuring colour temp at home