Grey, Green, and Black & White

This is a question about the use of color filters for B&W photography. I have a scene consisting of graffiti on a grey concrete bridge abutment surrounded by greenery. I have made a photograph without filters, and as I feared, there is virtually no tonal separation between the abutment and the surrounding greenery, the grey of the concrete photographs as the same shade of grey as the green leaves and bushes. (I have not posted the image, because the graffiti that attracted me is political, so some will enjoy the image, but others will be offended.) I have a reasonable number of color filters, but don't even know which to try (i.e. I can separate green and red, or blue and green, but am stymied by grey and green). Any suggestions?

Peter,

A filter will lighten its own color in relation to grey, and darken its complementary colors. A red filter will darken the green and the grey will stay the same (theoretically, and given that you apply the correct filter factor). In the other direction, a green or cyan filter will lighten the foliage somewhat in relation to the grey. Given that green foliage often has a lot of hidden red/yellow in it, the filter might not work as intensely as you might expect, but I think you should be able to get some separation. Use a #25 red to darken and a sharp cutting green filter like the #58 or the #44 cyan filters to lighten. Using the common #11 (X1) green filter will have less of an effect, since the filter is really "yellow green" and passes more red than meets the eye.

Keep in mind, that graffiti colors will be affected as well.

Extending development, if you can, will enhance the filter separation too. And, there's always dodging, burning and bleaching...

Best,

Doremus

Doremus, Thanks so much, exactly what I needed! I had already played a little in PS just to see the effect of dodging and burning, but those are always more difficult to do in the analog world without leaving a halo or other artifact showing where you burned or dodged, so the filters and extended development (easy with HP5+ and Pyrocat, my usuals) is just what I was looking for.

Just view the scene in front of you through respective filters, one at a time, held in front of an eye. Pan film doesn't see colors exactly like human vision does, but you'll still get a good idea that way. Sometimes I carry a pair of red-tinted laser glasses with me, just to readily visualize the effect of a red or deep orange. For something like graffiti, having along a relatively dark green like a Hoya X1 or 58, along with a reasonably deep red like a 25, seems best. In certain cases, a 47 deep blue might also be warranted.