People engaged in ordinary everyday activities. Rhythmic patterns of light and dark, or line and solid. Such are photo-stories where color does not usually play a role, and where its presence may detract from the story.
I shoot in black-and-white — or grayscale, as the purists call it — when I want to tell such a story, where color does not play a role, because I want the story to "sing." On the other hand, there are many subjects — fall foliage, flowers, fashion, festivals, to name a few — where color is part of the story, and accordingly, I shoot in color.
And then there are subjects not so easily pigeon-holed. We're all familiar with Ansel Adams’ spectacular landscape photos in black-and-white. His photos sparkled because he mastered the technique of creating a long, nuanced tonal range, all the way from pure black to pure white, a technique that he championed throughout his lifetime.
For me, above all, shooting in grayscale is an artistic experience, because it is transformative — changing an everyday image to one with secret powers to reveal, inspire and instruct.