click to enlarge, or see it on Flickr
Shutter Speed: 1/8
Actually, I think this photo looked better in color, with some saturation added. It was taken back in October 2009, and I dug it up today in a quest for a suitable image to monochrome for this post. But I needed something that showed the effects of this method, and this photo certainly does. Here's how it works:
1. Crop your photo to desired size.
2. Optimize it as you normally would (any levels adjustments, brightness/contrast, etc.) Leave out any saturation adjustments.
3. Duplicate the background layer. Name this layer "Hue."
4. Desaturate the "Hue" layer.
5. Change the blending mode of the "Hue" layer to "Hue."
6. Select the Background layer (should be on bottom)
7. Open the Image>Adjustments>Hue & Saturation dialogue box (cmd+u on Mac, ctrl+u on Windows)
8. Change the hue of the background layer around. You'll notice that some areas will go darker and some will go lighter, but since the monochrome layer on top is masking the color, all you see is adjustments in the brightness. I usually stop when I find a nice contrast-y setting that doesn't make my image look flat. Try playing with Saturation, too; it gives some interesting effects.
9. When you're happy, flatten your image and open Image>Adjustments>Brightness & Contrast.
10. Adjust your brightness and contrast as desired. I find that extra contrast helps solve the "flatness" problem that B&W images sometimes have.
If you use this method to black and white a photo and want to share it, feel free to post a link in the comments!