“Don’t press desaturate!” Use Lab mode, channel mixer, copy a single channel. There are a lot of different methods for creating Black and White images from your color photos. Adobe has addressed this growing need in CS3 by adding the black and white adjustment. Thankfully this adjustment is available as an adjustment layer. By allowing us to control the luminance of 6 different color regions, we can create beautiful grayscale images with superior control of the mix.
Here is an image that I shot down in Miami Florida, we are going to convert it to grayscale.
Choose the Black and white adjustment layer, or choose it from the Image>Adjustments menu
We have 6 sliders that control the amount of luminosity in the Reds, Yellows, Greens, Cyans, Blues and Magentas
Notice that adjusting the yellow slider has a huge impact on the night lighting of this scene. This is beautiful because we can control the intensity of this lighting. With the RGB channel mixer it would be difficult to target the yellows. We could have used CMYK, but with such a small color gamut we would have lost too much in the other regions.
Adjust all the sliders until you are happy with your mix. The great thing about the adjustment layer is the ability to change these settings anytime we like. Be warned though, I have noticed that if you push the sliders too far, noise can be introduced to your image.
Choose the tint button and adjust the sliders for a nice sepia tone or monotone look, very nice!