Primarys

[Protean]

ok, so with light the primary colors are rgb right? not ryb like with paints...

so what are all the color combos for teh secondary colors then i.e.

r+g=?
r+b=?
g+b=?

iow. what does the color wheel for light look like?

 

[Torus34]

Oh, boy! Have you ever opened a can of worms!

When discussing light, you have to be a bit careful of the context.

The three colors for color slides and for color negative film are different.

If you're talking about the color temperature of the light, you're involved in the infrared, red, orange, yellow, white, blue sequence of black body radiation.

If you're enlarging color negative film, the three important colors are yellow, cyan and magenta.

If you're using a color head enlarger with variable contrast paper, yellow and magenta are the colors which matter.

If you are controlling gray density of specific objects in a B&W image, you'll get into color filters covering the full rainbow range.

And infrared film? That's a story in itself.

 

[markc]

This might help: http://www.fi.edu/color/

 

[Protean]

that link help a lot, thanks.

and wow, glad i don't do any film stuff yet lol

 

[Tiberius]

Light is based on the adding of colors - Red, Green, Blue. When you add red and green you get yellow, green and blue is cyan, etc. Painting pigments are based on the subraction of colors - Red Paint absorbs green and blue light, etc. With pigments, mixing red and green will give you a hideous brown color. The addition/subtraction confusion is what causes the different results.