The "Channel Mixer" is also a great tool for Black & White conversions:
- In case of multi-layered image, select the uppermost layer and stamp all visible layers [Alt+Ctrl+Shift+E].
- In the Effects palette, double-click the "Channel Mixer" thumbnail.
- At the dialog bottom, check the "Monochrome" option. The image turns to grayscale.
- Redistribute luminance with "Red", "Green", "Blue" sliders to achieve the best possible tone and detail (screenshot).
- If you need a kind of "color spot" effect, add a mask using the "Add Layer Mask" command.
