Change the Brush in Photoshop CS5 Tools Panel
Grouped together in the Tools panel of Photoshop Creative Suite 5 are the tools used for painting and retouching images. As you click to select different painting tools, note the Brush menu (second from the left) on the Options bar. Click the arrow to open the Brushes Preset picker. Use the Master Diameter slider to make the brush size larger or smaller and to change the hardness of the brush.
The hardness refers to the fuzziness of the edges; a softer brush is more feathered and soft around the edges, whereas a harder edge is more definite.
If you don’t feel like accessing the Brushes Preset picker every time you want to make a change, press the right bracket (]) several times to make the brush diameter larger or press the left bracket ([) to make the brush diameter smaller. Press Shift+] to make the brush harder or Shift+[ to make the brush softer.
Choose Window→Brushes to see a list of brush presets, plus more brush options you can use to create custom brushes. You can also choose other brush libraries from the panel menu.
When you select an additional library, a dialog box appears, asking whether you want to replace the current brushes with the brushes in the selected library. Click the Append button to keep existing brushes and add the library to the list, or click OK to replace existing brushes.
Access the Brushes Preset picker while you’re painting by right-clicking (Windows) or Control-clicking (Mac) anywhere in the image area. Double-click a brush to select it; press Esc to hide the Brushes Preset picker.