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What do you call somthing that only lets certin colours through???
- Jamie (age 13)
Spotswood Collage, New Zealand
We call these filters, or colored filters. Typically they are made of
glass or plastic and are commonly used in photography. Some cameras
have threaded mounts around their lenses so you can screw one of these
With digital photography, you can often accomplish the same thing
after the fact by touching up the picture with a computer program. The
advantage here is that you have freedom to change the color filtering
process many times with the same image on a computer, but with film you
only get one try per frame (you have to change filter and shoot again
if you want to try something else).
Colors can also be separated with prisms and diffraction gratings.
You need to block out the colors you don't want with a piece of
material which is often called a collimator. The whole apparatus is
called a spectrometer, and is often used for measuring the intensity of
different-colored components of light.
(republished on 07/27/06)
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