On 17 Feb 2006 11:54:35 -0800, "BJ Conner"
wrote:

I am asking this here because I know some of you are very knowledgeable
on the subject. I want to take digital photos of black and white
drawings with red and green pencil markups. The reds and greens are
not bright.
So far I can get the resolution I need but the reds and greens don't
show up so great. I think the problem is in the spectrum of the light
i am using. I have tried the flash on the camera, fluorescent
lighting, and sunlight.
I am going to build a stand to position the camera over the drawing (or
part of it). I will add lighting fixtures to the stand to get the
quantity of light but the quality of the light. I can get what ever
will work (metal halide, Ott lights, quartz etc.)
If you can suggest a better group I'll take it there, I found about 900
hundred photography groups.
Any way this has noting to do with who Cheny shot or Lie, Spin and
Deny.


As far as lighting goes, your lights should be positioned at 45 degree
angles either side of the camera with the paper on a flat surface and
the camer three dimensionally perpendicular to it. The 45 degree
angle generally eliminates glare and gets the best colour saturation.

When using different types of lights, you'll get a different colour
temperature that can be compensated for via the white balance control
on your camera. Be careful to use lights meant for colour photography
as some types of lights can be missing part of the light spectrum.
Our eyes/brain adjusts for colour temperature and missing spectrum but
the camera can't. It records what it sees. White balance control is
probably your best bet.

Second problem comes from the curse of digital photography --
automation. No idea on the ratio of black to white on your drawings
or the metering pattern of the camera but odds are, your image is more
white than black so it's not close to 18% reflectance of the grey
scale calibration of camera meters. As a consequence, your image is
probably underexposed. That'll muddy up the colours, fer sure. If
your camera can bracket, shoot from 2 stops under to 2 over in half
stop increments and you'll probably can get one that's perfect. I
realize colour/contrast/brightness/gamma etc. can be adjusted in
software but nothing beats getting the right exposure.

HTH

Peter

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