Now wait, why would anybody use a colored filter for BW pictures? You don't see color in black and white pictures!
True, but whatever is shown on a black and white photography (mostly) has colors in reality. The idea of using a color filter is to enhance certain colors of the image. The following table gives an overview:
|
Color
|
Is lightened by (Wratten number)
|
Is darkened by (Wratten number)
|
|
Red
|
Orange (21) Red(26)
|
Blue (47A ) Yellow-green(11)
|
|
Yellow
|
Yellow-green(102) Yellow(3)
|
Blue(47A)
|
|
Orange
|
Yellow(3) Red(26) Orange(21)
|
Blue(47A)
|
|
Green
|
Yellow(3) Yellow-Green(11) Green(56 )
|
Orange(21) Red(26)
|
|
Blue
|
Blue(47A)
|
Red(26) Orange(21) Yellow-green(11) Yellow(3)
|
Fine, you say, most people don't use BW film anymore to take pictures but use digital cameras, why would they be interested? Because you can use these techniques in your imagery software, and for those who can't there is the free program called Filtersim by Mediachance (http://www.mediachance.com) that emulates all relevant photographic filters.
And to the practical part we will concentrate on those who would use Filtersim (or similar) as I suppose that those who use selective colors in Photoshop (or similar) are advanced enough to understand the procedures.
So then lets take a typical postcard shot (and yes, it was taken to be put on a postcard) of Darmstadt's Five Finger Tower. If we convert it to gray scale it surely does not look very exiting as it lived by its saturated colors... to give it a little more zing we could try to darken the blues and the greens.
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Wedding tower (fFive Finger tower) by Alf B. Meier
We make a copy of our image(never work on the original as you could destroy it) and load it into Filtersim, we look in the table above and see that Orange(21) darkens both green and blue and we apply that. Once we convert the image to BW we see that the contrasts have improved enough to make it an acceptable picture.
Because there is a slight loss in brightness (which happened with the “real” filters and BW material too) you'll have to adjust it. In this case I tried to equalize the white building besides the tower.
We could have used red(26) as filter, but that would have darkened the tower's burned orange too and except a higher contrast in the sky we would have gained nothing.
original, orange filter, red filter
Normed filters are a powerful tool for those wanting to enhance BW photography, and certainly one that every photographer should know, even then when he never plans to apply it.
